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plnelson
03-26-2019, 12:43 PM
I use zinc white a lot as a mixing white and last night I happened to notice that my Windsor and Newton Zinc whites - both artist-grade and water mixable, have lead in them. Since I have other zinc whites without lead I did a Google search to learn more and I found something unexpected . . .

A total hit-piece on Zinc White by Rublev! (https://www.naturalpigments.com/artist-materials/zinc-white-oil-paint-color/)

... it's brittle, it cracks, it delaminates, it gives you herpes ... Okay, I made that last one up, but basically they made it out to be a disaster and implied that no one should use it, and they don't sell zinc white.

But as we all know, Rublev makes LOTS of lead whites. So my question is, is zinc white really as bad as they make it out to be, or is this some kind of marketing hype to get us to buy lead white, instead?

Side question: is lead paint really any worse or more toxic than other heavy-metal paints with cadmium, cobalt, etc? This article on Pubmed from the International Journal of Molecular Science (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3127121/) says, "Lead is considered to be among the most dangerous metals for human health because it affects the central nervous system, causes anemia and gastrointestinal damage, and is associated with alterations in genetic expression [11–15]. Cadmium is even more dangerous, being 10 times more toxic than lead,"

... but my main question is really about whether zinc white is as bad as they say.

stapeliad
03-26-2019, 12:52 PM
Friendly Mod Note:

Zinc has been discussed over and over on this forum.
Please keep all discussion civil, we don't need another argue-y thread on the topic.

Red 9
03-26-2019, 01:10 PM
Very good article about zinc - https://www.justpaint.org/zinc-oxide-reviewing-the-research/


I have no problem with the small amount of zinc that is blended into most titanium white and some colors, but you definitely need to exercise caution using straight zinc white, especially on canvas.

bhindi
03-26-2019, 01:33 PM
I have been using zinc white in mixes in the past 3 years and thus far, have not seen any bad effect of it, if used carefully, i.e. painting on a rigid surface, following the rules of fat over lean and ensuring appropriate dry time between layers. If painting in layers, areas containing zinc white will exhibit strong beading.

Pinguino
03-26-2019, 01:41 PM
Plnelson, please search first. That Rublev piece has been repeatedly mentioned and discussed.

RomanB
03-26-2019, 01:54 PM
1. It was long ago known that Zinc White is problematic in artist's oil paints, in any quantity, no big news.

2. The problem became acute when new restrictions on Lead White were enforced. Since there are only two widely available alternative pigments, Titanium White and Zinc White, manufacturers had to make substitutes using Zinc White and add it in many mixtures. Results are already catastrophic.

3. Lead White is toxic if used carelessly and the most problematic is that it is a cumulative poison. On a bright side, if you'll use it responsively and with required precautions, it is not that dangerous. There are blood tests for Lead, its levels could be monitored if you are concerned.

4. There is no equivalent to Lead White in oil painting. If it will be banned further, I'll buy it from drug dealers.

plnelson
03-26-2019, 03:26 PM
I have been using zinc white in mixes in the past 3 years and thus far, have not seen any bad effect of it, if used carefully, i.e. painting on a rigid surface, following the rules of fat over lean and ensuring appropriate dry time between layers. If painting in layers, areas containing zinc white will exhibit strong beading.

I paint sometimes on panel and sometimes on canvas, which is not rigid. I do follow fat over lean rules but I'm not particularly careful about ratios or anything like that. Titanium white is too opaque for many of my uses.

My oldest painting with extensive zinc white (shown here) is about 12 years old and it's on canvas
http://www.wetcanvas.com/Community/images/26-Mar-2019/21373-suzb09.jpg

... and so far it's in good condition. But that article has me worried so should I avoid zinc-white in the future, and if so what's my best substitute?

plnelson
03-26-2019, 03:57 PM
1. It was long ago known that Zinc White is problematic in artist's oil paints, in any quantity, no big news.

2. The problem became acute when new restrictions on Lead White were enforced. Since there are only two widely available alternative pigments, Titanium White and Zinc White, manufacturers had to make substitutes using Zinc White and add it in many mixtures. Results are already catastrophic.

3. Lead White is toxic if used carelessly and the most problematic is that it is a cumulative poison. On a bright side, if you'll use it responsively and with required precautions, it is not that dangerous. There are blood tests for Lead, its levels could be monitored if you are concerned.

4. There is no equivalent to Lead White in oil painting. If it will be banned further, I'll buy it from drug dealers.

Could others comment on whether this is a consensus view? In the link I posted in the OP to the Journal of Molecular Science article it said that cadmium is 10 times as toxic as lead. Now I understand that they're talking about the elements cadmium and lead, and that in the paint formulation it might be a different story. So how does the toxicity of lead paint compare to cadmium paint? Comparing the MSDS's doesn't seem to suggest there's a dramatic difference.

plnelson
03-26-2019, 04:13 PM
Plnelson, please search first. That Rublev piece has been repeatedly mentioned and discussed.
Could you suggest a good search formulation because I did try such a search, typing Rublev zinc white in the Wet Canvas search box and I got a zillion hits but they were totally random. It appears that if ANY of those words appeared in the thread it would generate a hit. Is there a way in the WetCanvas search to formulate it so it has to have the word Rublev AND the phrase "zinc white" in the same article?

BTW I also did a Google Search of Wet Canvas (site:wetcanvas.com rublev "zinc white") and while there are lots of articles about zinc white and lots of articles about Rublev, it wasn't obvious how to find where this specific article was discussed extensively. I'm sure you're right that it's out there someplace, but I think between the WetCanvas search and the Google search I did my due diligence in searching first.

RomanB
03-26-2019, 04:18 PM
Could others comment on whether this is a consensus view? In the link I posted in the OP to the Journal of Molecular Science article it said that cadmium is 10 times as toxic as lead. Now I understand that they're talking about the elements cadmium and lead, and that in the paint formulation it might be a different story. So how does the toxicity of lead paint compare to cadmium paint? Comparing the MSDS's doesn't seem to suggest there's a dramatic difference.

Here are EU REACH dossiers on basic lead carbonate (https://echa.europa.eu/registration-dossier/-/registered-dossier/12705/7/2/1) and cadmium sulphide (https://echa.europa.eu/registration-dossier/-/registered-dossier/14815/7/2/1). Both are toxic.

plnelson
03-26-2019, 04:36 PM
Here are EU REACH dossiers on basic lead carbonate (https://echa.europa.eu/registration-dossier/-/registered-dossier/12705/7/2/1) and cadmium sulphide (https://echa.europa.eu/registration-dossier/-/registered-dossier/14815/7/2/1). Both are toxic.
I think we all know they're both toxic and your links confirm this. Reading the text of the links makes it hard to do a direct comparison - one used rats, one used hamster and monkeys; they used different measurements, and while the lead one (rats) didn't come out too bad, they had a disclaimer saying that they were classifying it severely based on human toxicity.

So I really couldn't tell, reading those reports whether the lead is more dangerous than the cadmium, but everyone acts like it is and you can't buy it easily, whereas cadmium yellow (which is CdS) you can buy at Michael's and people are pretty ho-hum about it. Are we too blase about cadmium or too paranoid about lead?

Pinguino
03-26-2019, 04:41 PM
Ah, often a better way to search WC is to directly use Google. This pulls up a variety of good results. The main search term is the URL of the linked article, and the site term restricts results to pages here at WC. Ignore the link, since I cannot make it disappear using the link-breaker:

https://www.naturalpigments.com/artist-materials/zinc-white-oil-paint-color/ site:wetcanvas.com

RomanB
03-26-2019, 05:06 PM
Are we too blase about cadmium or too paranoid about lead?

First. Cadmium is relatively rare, you'll have to try hard to find it around. Lead has much more uses, that's why it lures more attention of politicians and bureaucrats.

Gigalot
03-26-2019, 05:27 PM
4. There is no equivalent to Lead White in oil painting. If it will be banned further, I'll buy it from drug dealers.
Mecklemburg is a father of Zinc White haters, but he change now his mind about Zinc White. Today, he is really sure, that optimal amount of Zinc White is necessary addition to form stable Titanium-Zinc White paits formulation. Lead is't the only white, we can always try to use Zinc-Titanium mixture with great success.
BTW, Zinc White made by burning of metallic Zinc always contains traced amount of Lead oxides. Medical grade of Zinc White do not contains such impurities.

plnelson
03-26-2019, 06:07 PM
First. Cadmium is relatively rare, you'll have to try hard to find it around. Lead has much more uses, that's why it lures more attention of politicians and bureaucrats.
I don't think Cadmium is rare at all. Both of the art supply stores near me (northeast US) have lots of cadmium pigments - yellows, red, etc. Neither of them carry lead white (except the aforementioned Winsor Newton zinc white with the California lead warning, but I suspect that's just a trace)

DebWDC
03-26-2019, 06:24 PM
Hi plnelson -
I have found that MITRA has a lot of information on zinc:
https://www.artcons.udel.edu/mitra/forums/question?QID=312
and it has a pretty nice search function.

Regarding your side question: dangerous under what conditions, which compound or form of the heavy metal, type of exposure (skin, inhalation, ingestion, in your ear…), length of exposure, age of person (child or adult), etc.? A blanket response would not be helpful, as the details for each of the factors above will give varying results.

I don’t paint using gloves, and I also don’t finger-paint much. I also don’t worry about exposure to heavy metals in oil paint, but I am careful and methodical.
Deb

ps - I think you may have misunderstood RomanB's response. I suspect he is not referring to art supplies, but to ordinary non-industrial applications, such as old usages of lead in paint, gasoline, lubricants, water pipe solder, and so on.

plnelson
03-27-2019, 04:42 PM
Regarding your side question: dangerous under what conditions, which compound or form of the heavy metal, type of exposure (skin, inhalation, ingestion, in your ear…), length of exposure, age of person (child or adult), etc.? A blanket response would not be helpful, as the details for each of the factors above will give varying results.
If we're talking about artists' paint then most those things are the same for both the cadmium and the lead for a given artist. So if I handle lead paint and cadmium paint the same and use a similar amount of it, is the lead going to present a greater danger to me than the cadmium? I'm asking because most of us use cadmium paints, and you can buy them anywhere, but many companies, e.g., Gamblin, no longer make lead paint, and many art supply stores don't sell lead paint. Is that because of emotion or science?

FWIW I was a ham radio operator and electronics hobbyist when I was younger so I've probably been exposed to a lot more lead from solder than I'll ever be from paint.

DebWDC
03-27-2019, 08:48 PM
Hi Plnelson –
Well, I respectfully disagree. All artists are not the same age, do not apply the paint the same way, use different mediums and dilutants, may or may not have small children or pets or family members with health problems, and so on. All these make a difference in how dangerous, potentially, the paint may be. So who is this “given artist”? If the given artist is a 3 year old child who finger paints, the risks are higher than if the given artist is a careful adult who does not finger paint.

Also, if I am interpreting your response correctly, it seems that you are assuming that the lead and cadmium paint have similar ways and degrees of being absorbed by the human body (pigment particle size may play a role here), and have similar health consequences. I am not a chemist or a doctor, so I rely on experts who have much more information than I do. So, I suggest the Rossol book “The Artist’s Complete Health and Safety Guide.”

Could you share with us what research you have done on this, from MITRA or the Rossol book or other sources? We could all benefit from more information.

Deb the details devil

plnelson
03-27-2019, 09:25 PM
Hi Plnelson –
Well, I respectfully disagree. All artists are not the same age, do not apply the paint the same way, use different mediums and dilutants, may or may not have small children or pets or family members with health problems, and so on. All these make a difference in how dangerous, potentially, the paint may be.
I realise that all artists are different, but how does that inform the question of whether lead is more dangerous than cadmium, or vise versa?

My point is that right now lead seems to be Public Enemy Number One, with stores and paint manufacturers discontinuing it, but no one is discontinuing cadmium. So does that mean cadmium is safer, or is it an emotional response to lead?


Also, if I am interpreting your response correctly, it seems that you are assuming that the lead and cadmium paint have similar ways and degrees of being absorbed by the human body (pigment particle size may play a role here), and have similar health consequences. I am not a chemist or a doctor, so I rely on experts who have much more information than I do. So, I suggest the Rossol book “The Artist’s Complete Health and Safety Guide.”
I'm not assuming anything- I'm simply asking the question. MITRA doesn't seem to have anything on this and I'm reluctant to buy the Rossol book only to find out that it doesn't either.

Remember, this thread is about an article by a company with the world's largest selection of lead paints, attacking zinc paints. I am persuaded that maybe I should stop using zinc paints in favour of lead ones and since I already use cadmium paints and take appropriate precautions, I was wondering whether lead ups the ante or maintains status quo ante, regarding risk.

But I don't know how dangerous lead paints are compared to cadmium so I was hoping someone on the technical forum would know since pretty much every artist has to make this decision.

Ron Francis
03-28-2019, 01:05 AM
Mecklemburg is a father of Zinc White haters, but he change now his mind about Zinc White. Today, he is really sure, that optimal amount of Zinc White is necessary addition to form stable Titanium-Zinc White paits formulation.
Can you post a link please?
Here is a quote from Sarah Sands at MITRA which confirms this.
Marion Mecklenburg continues to feel that some as-yet-defined percentage of zinc could be beneficial, providing some film strength to titanium white and acting as a source of active metal ions, which are thought to be critical in the overall structure of a paint film.
Note that common percentages of zinc in titanium range from 2% to 50%.
(From someone posting email correspondence with manufacturers at MITRA)

Pinelson,
There are 3 links resources posted so far, including yours from Natural Pigments.
These are experts in the field who have access to the latest information.
I would be wary of taking advice from anyone in this group unless it is backed up by empirical evidence. I generally don't think much anecdotal evidence unless they are controlled tests. (As opposed to, "my painting with zinc is 15 years old and looks fine".)

Gigalot
03-28-2019, 02:40 AM
Can you post a link please?
Here is a quote from Sarah Sands at MITRA which confirms this.

I do not have scientific article about that. I think, that they are still trying to do many tests. But he was talking about Zinc. The optimal concentration of Zinc White in paint depends of particle size of Zinc White pigment, drying oil nature and used siccative. Safflower oil binder needs more Zinc to dry..The range is 1%-2% may be.

AnnieA
03-28-2019, 05:19 AM
If we're talking about artists' paint then most those things are the same for both the cadmium and the lead for a given artist. So if I handle lead paint and cadmium paint the same and use a similar amount of it, is the lead going to present a greater danger to me than the cadmium? I'm asking because most of us use cadmium paints, and you can buy them anywhere, but many companies, e.g., Gamblin, no longer make lead paint, and many art supply stores don't sell lead paint. Is that because of emotion or science?

FWIW I was a ham radio operator and electronics hobbyist when I was younger so I've probably been exposed to a lot more lead from solder than I'll ever be from paint.
Let me start by saying I am in no way an expert on these issues. But the reason I will never use lead paint is that it has more propensity for toxic exposure than cadmium paint. Here's an excerpt from the CDC:

You can be exposed by breathing-in lead fumes or lead dust.

Lead fumes are produced during metal processing, when metal is being heated or soldered. Lead dust is produced when metal is being cut or when lead paint is sanded or removed with a heat gun.

Lead fumes and lead dust do not have an odor, so you may not know you are being exposed.

You can be exposed by ingesting lead dust.

Lead dust can settle on food, water, clothes, and other objects. If you eat, drink, or smoke in areas where lead is being processed or stored, you could ingest lead dust. Not washing your hands before you eat or touch your mouth are also ways you could ingest lead.

Though not always the case, ingested lead may leave a metallic taste in your mouth.

You can be exposed by coming in contact with lead dust.

Some studies have found lead can be absorbed through skin. 1 If you handle lead and then touch your eyes, nose, or mouth, you could be exposed. Lead dust can also get on your clothes and your hair. If this happens, it’s possible that you may track home some of the lead dust, which may also expose your family.
https://www.cdc.gov/niosh/topics/lead/exposure.html
Although the material above mostly talks about lead dust, I'm assuming that touching lead paint would be equally as problematic. But that's really speculation.

OTOH, my understanding is that cadmium does not enter easily through the skin and is relatively safe as long as you don't eat it. Here is something on Cadmium from the CDC:
How Cadmium Is Absorbed
The principal factor determining how much cadmium is absorbed is the route of exposure. Once exposed, how much cadmium is absorbed depends on many factors:

age,
gender,
smoking, and
nutritional status.
As a cumulative toxin, cadmium body burden increases with age. Women have been shown to have higher blood levels of cadmium than men. Typically women, with lower iron status, are believed to be at risk for greater absorption of cadmium after oral exposure (Olsson et al. 2002).

Inhalation
Once in the lungs, from 10% to 50% of an inhaled dose is absorbed, depending on particle size, solubility of the specific cadmium compound inhaled, and duration of exposure (Jarup 2002). Absorption is least for large (greater than 10 micrometers [µm]) and water-insoluble particles, and greatest for particles that are small (less than 0.1 µm) and water soluble. A high proportion of cadmium in cigarette smoke is absorbed because the cadmium particles found in that type of smoke are very small (ATSDR 1999).

Ingestion
Most orally ingested cadmium passes through the gastrointestinal tract unchanged as normal individuals absorb only about 6% of ingested cadmium, but up to 9% may be absorbed in those with iron deficiency (ATSDR 1999). Also, cadmium in water is more easily absorbed than cadmium in food (5% in water versus 2.5% in food) (IRIS 2006). The presence of elevated zinc or chromium in the diet decreases cadmium uptake.

Dermal
Absorption through the skin is not a significant route of cadmium entry; only about 0.5% of cadmium is absorbed by the skin (ATSDR 1999).

Excretion of Cadmium
Absorbed cadmium is eliminated from the body primarily in urine. The rate of excretion is low, probably because cadmium remains tightly bound to metallothionein, MTN, which is almost completely reabsorbed in the renal tubules.

Because excretion is slow, cadmium accumulation in the body can be significant. Cadmium concentration in blood reflects recent exposure; urinary cadmium concentration more closely reflects total body burden. However, when renal damage from cadmium exposure occurs, the excretion rate increases sharply, and urinary cadmium levels no longer reflect body burden.
https://www.atsdr.cdc.gov/csem/csem.asp?csem=6&po=9

It appears to me that whatever is the relative toxicity in general between the two, lead is the more dangerous because it enters the body more easily. But I dunno...I'm a woman and an ex-smoker, so as I look at all that, I'm thinking maybe I should stay away from cadmium paints too, just in case.

Ron Francis
03-28-2019, 06:20 AM
Regarding the toxicity of cadmium compared to lead, here's a quote from Ben Sones at the 'Painting Best Practices' facebook group.
(I know George Ohanlon has said something similar, but I can't find it.)

Cadmium sulfide pigments used by artists are manufactured to be insoluble, which means that it mostly just passes through your body when ingested, without being absorbed into your blood. You can still poison yourself, but you'd need to eat rather a lot of cadmium paint to do it. It's orders of magnitude less hazardous than, say, lead. The largest danger posed by cadmium sulfide is inhalation (it's a carcinogen)--especially inhalation of cadmium vapor (so if you smoke, don't do it in the studio, or allow any paint to get onto your cigarettes)

Ron Francis
03-28-2019, 06:23 AM
I do not have scientific article about that. I think, that they are still trying to do many tests. But he was talking about Zinc. The optimal concentration of Zinc White in paint depends of particle size of Zinc White pigment, drying oil nature and used siccative. Safflower oil binder needs more Zinc to dry..The range is 1%-2% may be.
I was thinking somewhere around those numbers. Thanks.

Gigalot
03-28-2019, 07:26 AM
Regarding the toxicity of cadmium compared to lead, here's a quote from Ben Sones at the 'Painting Best Practices' facebook group.
(I know George Ohanlon has said something similar, but I can't find it.)
That means Cadmium sulfide pigment is non-toxic when used on artists' oil paint manner. No pigment smoking or airbrush or burnig or acid treatment. Ingested cadmium sulfide is insoluble in stomach liquor, while high quality modern cadmium pigment do not contains toxic soluble impurities.

DebWDC
03-28-2019, 11:43 AM
Hi Plnelson –

Fair points and thanks for the clarification. My point, which I did not make clearly, is that the answer about relative risks of lead versus cadmium is always going to be dependent on the specific situational factors. Age of the given artist is a specific situational factor.

Lead is always more dangerous than cadmium when the given artist is a 3 year old child, because the child’s developing brain is more sensitive to neurological damage than an adult’s brain, and lead is more easily absorbable than cadmium, at least in pigment formulation. This is similar to the CDC warning pregnant women not to eat mercury-contaminated fish: not because of the potential damage to the woman, but rather to her developing fetus. Our colleagues here have posted some great sources: AnnieA and Ron Francis. So, yes, the age of the given artist is one important consideration in thinking about the relative risks. A blanket response for the relative risks cannot be given without the age of the given artist.

Some paint manufacturer owners and employees also work with conservators to find better solutions. They also contribute to MITRA and other forums. I think Mr. O’Hanlon did not attack zinc in order to increase his sales of lead paint. He posted research results. His company is one of several that I know of which offer different lead paints (Harding, Blue Ridge, Doak) because they apparently think lead is better than zinc. Other companies also offer lead paint, but I don’t know if they contribute to MITRA (Blockx, RGH, Williamsburg, Old Holland).

I think it is great that manufacturers are working with conservators to find better solutions. I have had the opportunity to speak to Mr. O’Hanlon before, and he impressed me as a sincere person who genuinely wants to help artists, and not as a money-grubbing capitalist. Of course he has to make a living. BTW, he used to post here on WC regularly, but has stopped. I think it is because he got tired of being challenged and mistrusted. You may wish to take a look at some of the vitriolic language used. Also some of the language used to castigate the owner of Blockx. Gah!

Another aspect to consider is the manufacturing life cycle costs and the different countries’ regulatory laws. I do not know, but suspect, that lead paint is more expensive to produce than cadmium in terms of pigment costs, protecting the employees, disposal of waste, filling out OSHA or other regulatory forms, liability insurance, etc. That greater expense passed on to the purchasers may decrease sales, which decreases incentive to manufacture, because economies of scale are lost. That decreased incentive to manufacturers means that they are more likely to stop making lead paint. Currently, only smaller manufacturers still make lead paint, and it is more expensive to buy than zinc paint.

Over the course of my day job career, I have ordered many technical journals and books through inter-library loans. I did not have to purchase them. You may wish to do the same for the Rossol book. I have found librarians are thrilled to process odd-ball requests.

Deb

ps - I was born and raised in Lake County, Indiana, which used to lead the US in weird brain cancers due to heavy metal environmental contamination. It remains an EPA superfund site. I think we have gotten much better about understanding and acting on pollution.

plnelson
03-28-2019, 12:08 PM
Hi Plnelson –

Over the course of my day job career, I have ordered many technical journals and books through inter-library loans. I did not have to purchase them. You may wish to do the same for the Rossol book. I have found librarians are thrilled to process odd-ball requests.
I'll see if I can order the Rossol through ILL. But this is, after all, the Technical forum where we tend to attract knowlegable geeks, and I'm sure many painters have already had to make the same decision about whether to use lead paint instead of zinc so they might already know some answers.

I already paint with gloves and don't eat while painting, and don't sand my canvasses, because of the cadmium. I agree that the CdS compound is less bioavailable than PbCO3 but I posted a link to an article in the Journal of Molecular Science that cadmium is 10 times as toxic (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3127121/), so how does that net out if you absorb less of it but what you do get is 10X as toxic? That's what I want to know.

I have a physical today and I was thinking of asking for a baseline lead test, so if I start using lead white I can have a followup a year later and see if it's changed.

DebWDC
03-28-2019, 01:45 PM
Hi Plnelson -
The article you linked to addresses lead and cadmium leached into food and ingested.
Therefore:
1. That specific situational factor – ingestion - defined the broader parameter of the research.
2. That research result does not apply to oil paints, unless you ingest them.
3. It supplies no basis for assessing risks for oil paint exposure unless you eat your paints.
4. Cadmium being “10 times more toxic” than lead is meaningless unless you eat your oil paint AND the forms of cadmium and lead used in food container glazes produced in Mexico (note the very specific factors here) are the same as in oil paints.
5. So you can’t “net out”

No kidding, the devil and truth are in the details.

Please let us know the results of your blood test. I asked my doctor years ago for a baseline lead test, he asked why, I explained I painted, and he said it wasn’t necessary unless I ate paint as a child. Someone here on WC a few years ago posted a personal experience about lead fumes from painting poisoning a family member (my recollection is vague) and medical treatment being necessary.
Deb

DebWDC
03-28-2019, 01:50 PM
Oops. duplicate post

plnelson
03-28-2019, 02:58 PM
Hi Plnelson -
2. That research result does not apply to oil paints, unless you ingest them.
Nobody intentionally eats paint and I'm sure most of us think we're being careful but epidemiological studies of painters have shown that we have a higher rate of types of hematological cancers, organ disease and neurological pathologies that are associated with toxic materials we use. So it's getting into some of us somehow.

I like to tell myself that it's those other artists who do careless things like eating while they're painting or not wearing gloves or an apron, and so I'm different. But since I do have a hematological cancer and such cancers happen at a higher rate with oil painters I can't be sure that there's not some hole in my armour.

BTW, I talked to my Dr and I will order the lead blood test (insurance probably won't cover it), and then I'll try lead paint for a year and test again. Also my library in eastern Mass. couldn't get the Rossol on ILL so they're going to see if they can get it from a university library on the other end of the state. Here's hoping.:crossfingers:

capnd
03-29-2019, 09:14 PM
I went to an art musem today and saw over a hundred oil paintings from the zinc-era. Monet, Van Gogh, you name it. Now .. I do not know what the conservationist may (or may not) have had to do to those ... but they all looked perfect. I have read with exhaustion every post and article on zinc. A lot of experts quoting experts, publishing this, publishing that ... conjecture. The proof is in the paintings. As to whether there is a marketing conspiracy against zinc to scare folks from established brands that still use zinc ... well lets just say that when a relatively up and coming brand sells a tshirt that says "friends dont let friends use zinc" ... well, i begin to lose trust in that company. And when another anti-zinc company's (based in brooklyn) buyout, coincides with mecklenberg releasing (unpublished) anti-zinc data ... and that company employs another publisher of many things questioning zinc, I lose trust in those two messangers. Sorry, but the conflicts of interest, at a minimum, must be factored into these questionings-of-zinc. The proof is in the paintings. Perhaps its only becuase none of them were wrapped around a steel dowel or painted on mylar, ehem. Lastly, while I'm not an anti-leader, the whole questioning of zinc isnt helping those of us who might seriously desire to merge away from it while preserving the more transparent characteristic we get from modern day lead .. ie., zinc. I get it ... companies want to make a buck, but conjecture (at best) and scaremongering (at worst) simply will not do.

plnelson
03-29-2019, 09:40 PM
I went to an art musem today and saw over a hundred oil paintings from the zinc-era. Monet, Van Gogh, Sargent, you name it. Now .. I do not know what the conservationist may (or may not) have had to do to those ... but they all looked perfect.
Do you know for a fact that they were painted with lots of zinc white? Jackson's art blog says that Sargent liked to use flake white.

capnd
03-29-2019, 09:46 PM
I may stand corrected on sargents oils. He used zinc in watercolor, so I assumed he was a zincer in oils too. I edited my post, thanks for the correction.

Gigalot
03-30-2019, 06:31 AM
Today we can replace both, Zinc and Lead by using Titanium WHITE, mixed with traslucent fillers like Calciium carbonate, Kaolin, Silica, Aluminum hydrate, Blank Fixe. That gives flexible result. The more Titanium White pigment added, the more opaque result we will achieve. Most manufacturers use some amount of zinc addition to bleach white color. Superior whitest Titanium White paint always contains bleaching Zinc additive.

Ron Francis
03-30-2019, 07:28 AM
Except it would not have the lead ions that gives strength and flexibility to paint that it's mixed with, as well as adjacent layers of paint through ion migration.

Gigalot
03-30-2019, 08:12 AM
Except it would not have the lead ions that gives strength and flexibility to paint that it's mixed with, as well as adjacent layers of paint through ion migration.
Lead white solubility is about 0,3% released lead ions, while Zinc White will release 0,5%-2% of Zinc ions with the same metallic ions activity or even stronger. A small amount of Zinc White greatly improves hardness of oil paint, but Zinc has excessive activity when compared with lead. So we must decrease amount of Zinc White addition to achieve exact effect, that lead can give. In rubber industry, they also used lead, but after lead was banned and now they use 1% zinc white in tire rubber as equal quality hardener. Recently, the new idea came to a chemists mind, that zinc can be also replaced by adding magnesium oxide MgO instead.

BTW, lead white has questioned ions activity, not exactly effective for upper layers of paint. Most effective are copper ions, for both drying activity, UV light absorbtion and migration effectiveness.

Ron Francis
03-30-2019, 08:30 AM
Lead white solubility is about 0,3% released lead ions, while Zinc White will release 0,5%-2% of Zinc ions with the same metallic ions activity or even stronger. A small amount of Zinc White greatly improves hardness of oil paint, but Zinc has excessive activity when compared with lead. So we must decrease amount of Zinc White addition to achieve exact effect, that lead can give. In rubber industry, they also used lead, but after lead was banned and now they use 1% zinc white in tire rubber as equal quality hardener. Recently, the new idea came to a chemists mind, that zinc can be also replaced by adding magnesium oxide MgO instead.
I don't believe for a second that you can equate zinc ions with lead ions.
As you said, zinc will act as a hardener, so much so that it will become brittle, whereas lead is more like a plasticiser.

Gigalot
03-30-2019, 08:37 AM
I don't believe for a second that you can equate zinc ions with lead ions.
As you said, zinc will act as a hardener, so much so that it will become brittle, whereas lead is more like a plasticiser.
Lead isn't plasticizer. You can compare pure titanium white in linseed oi with flake white. Such titanium white has much more softness, than any lead white. But 0,3 % of lead ions hardens oil paint and cross-link 3d structure of oil paint film. Zinc also hardens oil paint film, but with excessive cross-linkage because the solubility of zinc white in oil is much stronger. Therefore, the amount of zinc must be strongly limited, while solubility of lead white of 0,3% is probably optimal for oil paint films.
For umber oil paint, 17% of manganese oxide content is probably optimal to form manganese ions activity. Such umber has enough strenght and do not need to have excesive lead ions for that.

budigart
03-30-2019, 10:27 AM
A few days ago, Williamsburg announced it is removing all zinc from its paint.

To answer your question, yes, zinc is really bad stuff.

Take a look: http://www.justpaint.org/zinc-oxide-warn...practices/

Gigalot
03-30-2019, 12:40 PM
A few days ago, Williamsburg announced it is removing all zinc from its paint.

To answer your question, yes, zinc is really bad stuff.

Take a look: http://www.justpaint.org/zinc-oxide-warn...practices/
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:lol:

savras
03-30-2019, 12:51 PM
Here is the correct link:

https://www.justpaint.org/zinc-oxide-reviewing-the-research/

and it was actually posted over a year ago and discussed on this very forum as well.

Gigalot
03-30-2019, 01:01 PM
Here is the correct link:

https://www.justpaint.org/zinc-oxide-reviewing-the-research/

and it was actually posted over a year ago and discussed on this very forum as well.
Year ago Mecklemburg was totally sure, that Zinc is totalle bad. But recently he changed his mind.

plnelson
03-30-2019, 01:19 PM
Year ago Mecklemburg was totally sure, that Zinc is totalle bad. But recently he changed his mind.
Could you document where he changed his mind? Gamblin has a whole article about this but they don't mention him changing his mind, and if he has you would expect Gamblin would have mentioned it because they sell zinc paints but no lead paints:
https://gamblincolors.com/zincoxideinartistoilcolors/ (http://gamblincolors.com/zincoxideinartistoilcolors/)

DebWDC
03-30-2019, 02:10 PM
Hi capnd –

Thanks for posting your view on the whole zinc vs lead controversy. I suspect many people here on WC share your views. I think that posting conjectures without solid evidence about the duplicitous motivations of oil paint manufacturers and conservators is dishonorable and harms both the targets of the comments AND the WC readers who may believe those postings. As an aside, no wonder the manufacturers and conservators don’t post here anymore, or don’t post often.

I write these long posts because I hope they are useful in shaping WC members’ approach to thinking about the technical aspects of oil painting, and will lead to better painting practices.

As I point out ad-nauseum, evidence is only found in details, not in blanket statements. Details are actionable, meaning you can usefully apply them to your situation; blanket statements are not.

Here are examples of blanket statements:
- Don’t use zinc because it will cause delamination.
- You can use zinc because the pre-raphaelites did and their paintings are in good shape.
- Don’t use lead because it is poisonous.

Here are examples of detailed statements which one can apply to his or her own painting practice:
- Zinc oil paint has been shown, both through conservation experiments and through observation of actual oil paintings, to cause problems. It also has been observed that many oil paintings done with zinc have held up well. Since the mechanisms by which zinc interacts with other materials in an oil painting remain incompletely understood, you may wish to not use zinc, or to use it only on a panel and not stretched canvas, or only in very small quantities, or only if you use an alkyd medium.
- Lead paint can improve the flexibility and adherence strength of your paint layers, but you need to be careful to avoid accidental exposure because it is poisonous. So, if you have pets or small children who enter your studio, you may wish to not take that risk.

See the difference?

The nature, scope, and applicability of scientific research
My personal observation is that most scientific research in most fields (approaching a blanket statement here :) ) is not published in venues which the public can readily access. Articles in publically-accessible, peer-reviewed journals, such as in university libraries, are the tip of the research iceberg. Most research, both conclusive and inconclusive, is published in non-public venues, and is communicated directly in private correspondences, discussions at conferences, telephone calls, and so on. So, if conservationists publish research on zinc in a public venue at the same time a manufacturer announces he will stop zinc oil paint production, one cannot draw the conclusion that they are in cahoots or that the research is new. I suspect that research has been known to conservationists and oil paint makers for decades, and is replicated in other research organizations. What is new is that the public (WC) found out about it.

The applicability of research is narrowly defined, based on the specific details of the research. The further away one gets from those specific details, the less applicable the results are. An example of the difficulty in applying research results to one’s own practice is: to what extent one can apply the results of folding dried oil paint on canvas over narrow diameter dowels to one’s own oil painting on stretched canvas, especially if you are not going to make an origami out of it.

Some very good researchers don’t bother with publishing in peer-reviewed journals, because it is not necessary in their employment. Also, in some fields, the average time gap between doing the research and getting published is more than 7 years. So, to help the other researchers and contribute to the field of study, the research is more frequently communicated informally. (No, I am not going to cite sources for the above assertions. They are based in 30+ years of research, some of which is in how scientists and experts communicate. If you want to pursue, start with journals of informatics, knowledge management, and citation analysis.)

So, meanwhile back at the WC ranch…
Most of us here on WC are hobbiests, and even those of us who make a living from our art are not usually trained chemists or conservationists. So, we are not formally educated about the technical aspects of oil painting. Reading all the WC oil painting technical forum posts about zinc is a start to getting educated, but it is limited because the actual research is seldom posted, is subject to a lot of misrepresentation (those pesky blanket statements), and we can easily misinterpret the results because we are not trained chemists.

Deb

Gigalot
03-30-2019, 02:43 PM
Could you document where he changed his mind?
Ask Sarah Sands about that. She was talking with him and will know much details. As for me, I just completely agree with his last opinion.

Gigalot
03-30-2019, 02:49 PM
we can easily misinterpret the results because we are not trained chemists.

Some artists are or was professional chemists in coating industry :wave: That do not means too much, but something interesting. :)

mgaissert
03-30-2019, 03:54 PM
An article in Science News magazine talks about bubbles found in paintings by Georgia O’Keeffe and others. The bubbles are crystals caused by metal soaps, could be zinc or lead! Then again, one of the writers mentioned that lots of white oil paints have zinc added. So, although I love the appearance of paints when mixed with zinc white, it reduces the value without making the color look chalky, I no longer use it.

https://www.sciencenews.org/article/why-some-georgia-okeeffe-paintings-have-art-acne

I can’t say that O’Keeffe continued its use, but I saw a photograph of her smiling, on the back a motorcycle driven by Maurice Grosser. Don’t know the year. He probably mentioned this to her as they were both painters. In his book, The Painter’s Eye, (1951 HB, 1956 PB) he made it clear that he felt that Zinc had only one use and that was for the nose of sunbathers.

Gigalot
03-30-2019, 04:15 PM
https://www.sciencenews.org/article/why-some-georgia-okeeffe-paintings-have-art-acne

What I can found there:
"Metal soaps, which look a bit like white, microscopic insect eggs, form beneath the surfaces of around 70 percent of all oil paintings, including works by Rembrandt, Francisco de Goya and Vincent van Gogh. “It’s not an unusual phenomenon,” says Marc Walton, a materials scientist at Northwestern University in Evanston, Ill."

Rembrandt used Lead White however. And this Lead White makes a trouble with metallic soap formation on under many of old paintings. Including delamination and efflorescence. Lead is a cause of many troubles on old paintings, not Zinc White.

"Scientists in the late 1990s determined that these soaps form when oil paint’s negatively charged fats, which hold the paint’s colored pigments together, react with positively charged metal ions, such as zinc and lead, in the paint. This reaction creates liquid crystals that slowly aggregate beneath a painting’s surface, causing paint layers on the surface to gradually bulge, tear and eventually flake off."

Now, is anybody who can say why Zinc White is "No-No" additive and why Lead white is such a "Great" stuff?

Marc Kingsland
03-30-2019, 04:42 PM
......

Rembrandt used Lead White however. And this Lead White makes a trouble with metallic soap formation on under many of old paintings. Including delamination and efflorescence. Lead is a cause of many troubles on old paintings, not Zinc White.



In as much as I'm aware later delamination with lead white soaps isn't of a form of shaling but of small aggregates of lead soap loosening and falling off leaving small pock marks in the paint layer.
I don't recall either zinc or lead white causing efflorescence. In fact I thought metal soaps prevented it as the fatty acids involved in efflorescence were locked into the metal soaps.

plnelson
03-30-2019, 05:01 PM
An article in Science News magazine talks about bubbles found in paintings by Georgia O’Keeffe and others. The bubbles are crystals caused by metal soaps, could be zinc or lead! Then again, one of the writers mentioned that lots of white oil paints have zinc added. So, although I love the appearance of paints when mixed with zinc white, it reduces the value without making the color look chalky, I no longer use it.

https://www.sciencenews.org/article/why-some-georgia-okeeffe-paintings-have-art-acne
Besides blisters, they also have cracks. I was surprised how cracked a painting of hers I saw at the NY Metropolitan Museum of Art (IIRC it was a cows skull) was when I saw it recently. Much worse than many paintings I've seen from a century earlier.

Marc Kingsland
03-30-2019, 05:13 PM
I think it's only when paintings with zinc white are given rough physical treatment that the embrittlement is to be shown to any effect. Unless that happens, then they're perfectly sound just hanging on the wall.
I've only personally witnessed two contemporary artists work delaminate with zinc white, and both of these happened to involve many, many, layers of paint also in combination with an alkyd medium. With both artists the paint was quite thick but also quite even. So the visible weave of the canvas was often lost to sight. The paint shaled in thin sheets many inches wide from the surface. (They repaired them, god only knows how.) This never happened while they were in the artist's possession, so I suspect it still involved some form of (undeclared) physical shock.
Though I myself, pretty much only use lead white. Most paintings of the last hundred years contain zinc white, and most of these when well kept, are I'm sure, perfectly fine.

Gigalot
03-30-2019, 05:21 PM
I don't recall either zinc or lead white causing efflorescence.
Zinc and Lead soap efflorescence is an issue of mostly impasto paintings.

capnd
03-30-2019, 05:29 PM
What Mecklenberg did, well intentioned or not, was explode the artist oil industry, armed with dowel rods, and mylar. All this during, roughly speaking, a vulnerable time overall as the banning of lead was shaping up. So ... what do we have ... EU makers scrambling away from lead ... and US manufacturers making zinc the bogey-man and then, cashing in on looser lead regulations.

As far as Ms. Sands (aka, Williamsburg) we need much more than a justpaint article update giving zinc a puff of rescusitive breath. If you read her old posts they are all out assault on zinc, but always a little hedge of "we just don't know". So, people go to (Williamsburg) lead in droves and those in EU are grinding it up under the cover of night because they are now paranoid about zinc. Look at a tube of Williamsburg Zinc versus their Flake. Big, bold, Red lettering all over the tube of ZINC white, warning about the perils of using zinc. And on the tubes of Flake White, just an standardized lead warning .. in small black and white print.

I live in the US, so I guess I should not really be concerned about the EU, right? Wrong, many of the finest artist oil manufactureres are in the EU. So sign me up for the collusion theory here between mentioned parties. In the US we are, I suppose, a bit more skeptical ... but many, in the US, also like a fair fight. What Sands, George, Mecklenberg have done to zinc is a little backhanded ... and I think many would agree, that is using more polite wording than needed.

plnelson
03-30-2019, 05:37 PM
Ask Sarah Sands about that. She was talking with him and will know much details. As for me, I just completely agree with his last opinion.
Here is Sarah Sands' latest missive on this topic:
https://www.justpaint.org/zinc-oxide-reviewing-the-research/
... it references Mecklenburg's work extensively and near the end she says:
"And even today, Mecklenburg continues to hope that some small, as yet undefined percentage of zinc, can help stabilize the other paint layers, especially given the inherent weakness of paint films based on titanium white. (Mecklenburg, 2018) "

N.B. the word "hope"; nowhere does it say he's changed his mind.

BTW, the article in the link, above is a great summary of the whole situation with zinc. Lots of detail, graphs charts, and citations. On the other hand, as in my OP, I can't help but wonder if the motivation is driven by Williamsburg still selling flake white while competitors like Gamblin have abandoned lead. As an artist I resent having to make decisions about the longevity of my paintings, and my personal longevity when I can't be sure if what I'm reading is science or marketing.

capnd
03-30-2019, 05:47 PM
...near the end she says:
"[I]And even today, Mecklenburg continues to hope that some small, as yet undefined percentage of zinc, can help stabilize the other paint layers ...

It's a safe bet that the percentage of zinc will be oh so well defined (by Williamsburg?) if the US ever gets around to banning lead white in artist oils. Note, sarcasm. And frankly, at this point, I would not trust anything coming out of Mecklenberg or Sands.

Further ... the cheek, as they say in the UK, of her article ... it presumes there IS an unsafe level of zinc. We call that - beginning a dialog on a negative presumption. Ie., bias. MANY reputable high end artist oil manufactures are still using zinc in their mixes. Do they not have a say? Who died and made Mecklenberg and Sands the penultimate authorities here? Give me two people to both determine and define a percentage .. it's Gigaglot and Ron Francis .. lock em' in a lab and figure it out.

Ron Francis
03-30-2019, 06:01 PM
Now, is anybody who can say why Zinc White is "No-No" additive and why Lead white is such a "Great" stuff?
I'm astounded that you are trying to make this argument.
Lead in paint is forming these acne type aggregates, yes, but lead has kept paint flexible for over 400 years in Rembrandt's case, whereas zinc has caused delamination and cracking in recent paintings and can become extremely brittle in as little as 3 years.
Zinc oxide is highly reactive and saponifies rapidly, also causing these agglomerates to break through the surface.
"Zinc soaps show a preference to accumulate at the interfaces between layers of paint, or between the paint and ground" which seems like a probable cause of delamination to me.
It is also hygroscopic, which can cause problems.
From what I've read, the addition of a small amount of zinc to titanium may be beneficial, but to say that zinc can perform the same function as lead, or serve as a replacement for lead??
You may be on your own with that view.

PS, I said that lead "acted" like a plasticiser, not that it was one.

DebWDC
03-30-2019, 06:34 PM
Hi Gigalot -
Yes, I know you are a chemist. That is why I read your posts with great attention. :)

Hi capnd –
I find your posts disconcerting, to say the least. However, I repeat, to continue to post conjectures without evidence about the motivations of others is dishonorable. If you have evidence (facts) of the collusion of manufacturers and conservationists, rather than the string of logic you have expanded upon, please post it so we may all benefit. Your use of the following language is inflammatory: explode, armed, vulnerable, bogey-man, cashing in, all out assault, cover of night, collusion, backhanded, etc. That language contributes nothing to our understanding and is a detriment to the WC community.

If you do not have evidence of collusion, then I request that you retract your postings on this.

Deb

capnd
03-30-2019, 06:44 PM
to continue to post conjectures without evidence about the motivations of others is dishonorable.


"Dishonorable". Interesting word choice. So others who have profited by conjecture (that at least is not debatable) are not allowed to be challenged by conjecture? As the old saying goes, "you cannot pickup one end of the stick without picking up the other" ... and by god, Mecklenberg and Sands have picked up the stick with their assault on zinc.

I think we are all very, very, long overdue for some straight-talk. Artists chasing their tails, EU manufacturers being targeted, driving people toward lead, profiting by lead. Are those “honorable”? Think of me what you will.

Marc Kingsland
03-30-2019, 07:11 PM
I And frankly, at this point, I would not trust anything coming out of Mecklenberg or Sands.


I fail to see how it would be of any personal interest of Mecklenburg at the Smithsonian to have had a pre-planned result with his hundreds of paint samples. And one would of thought it might have been more reliably in Williamsburg interest to keep their head down from the issue and just keep selling tinted zinc paint.

capnd
03-30-2019, 07:31 PM
"to have had a pre-planned result with his hundreds of paint samples"
Yeah, wrapped around dowels and painted on mylar if I'm not mistaken. :lol:

I am not the originator of this theory ... and I never said it was a fact.
Ok, so I'll give you Mecklenberg. Had some data, felt compelled to share it and was within his scope as a conservator. Though, others, who have had a clear stake in the anti-zinc movement, monetized it ... and they have treated Mecklenbergs work as gospel. And as of yet, I have not seen Mr. M take issue with people capitalizing on his unpublished research. The movement has been irresponsible, unfair, confusing .. and because it drove some people to lead ... Dangerous. Think of all the artists who have perhaps stayed with lead. All because of what appears to be a useless, big, cad red herring of an debate.

Marc Kingsland
03-30-2019, 07:38 PM
I'd recommend that anyone with concerns about the issue do their own tests. I recently tested 4 whites on a piece of matt surfaced plastic.

1, Old Holland zinc white (I already knew this was brittle, I was using it as a bench mark)
2, As Spectrum clear oil paint. (Alumina Hydrate)
3, Winsor & Newton Transparent White. (?, titanium white , zinc white)
4, Winsor & Newton Iridescent White. (titanium dioxide coated mica)

After a few months of drying in sunlight the Results were; 1, cracked, delaminated. 2, cracked, delaminated. 3, no cracking no delamination 4, slight cracking, no delaminating

It's still early days, but the Winsor & Newton Transparent White performed well. Unfortunately I'm not actually a fan of the paint itself. I liken it to a light oily mousse. If you wanted a light oily mousse, then this is the paint for you. :wave: Clearly there's another pigment apart from titanium dioxide and zinc white in the tube, but its not listed.

capnd
03-30-2019, 08:28 PM
Interesting. Could you share how you primed the piece of plastic?
I've used OH zinc. I never recall having any brittleness, but I was painting on oil primed linen, not a plastic sheet.

Marc Kingsland
03-30-2019, 09:59 PM
Interesting. Could you share how you primed the piece of plastic?
I've used OH zinc. I never recall having any brittleness, but I was painting on oil primed linen, not a plastic sheet.

It wasn't primed. The point was to test the paint film to its limits of what it might possibly have to put up with if it was, say, painted on top of a smooth dry unabsorbent underlayer. (which I don't think is entirely impossible) The plastic sheet was then bent around a 1 cm thick dowel. Naturally most paintings aren't going to be treated this way. If the paint was applied over a good quality acrylic gesso of high tooth I doubt it would have delaminated. And as the cracked paint wouldn't have lifted away from the surface, the cracks wouldn't have been as noticeable either.

Brian Firth
03-31-2019, 12:28 AM
It does beg the question, if ultimate permanence is the goal, why does Rublev sell genuine vermilion, which has a demonstrable lack of lightfastness and permanence issues, among other dubious pigments? And boy do they think it's just dandy! :lol: Why does Willamsburg sell genuine alizarin crimson? I suspect the justification for those colors still being used is equally applicable to zinc white's continued use, yet their demonization has not reached the "friends don't let friends…" level of hysteria and marketing. They all fall under the umbrella of pigments not performing well in lab tests, and having known problems to conservators, yet on the whole not exhibiting the purported issues in real world use.

Marc Kingsland
03-31-2019, 01:44 AM
It does beg the question, if ultimate permanence is the goal, why does Rublev sell genuine vermilion, which has a demonstrable lack of lightfastness and permanence issues, among other dubious pigments? And boy do they think it's just dandy! :lol: Why does Willamsburg sell genuine alizarin crimson? I suspect the justification for those colors still being used is equally applicable to zinc white's continued use, yet their demonization has not reached the "friends don't let friends…" level of hysteria and marketing. They all fall under the umbrella of pigments not performing well in lab tests, and having known problems to conservators, yet on the whole not exhibiting the purported issues in real world use.

Not a silly question. I guess it's because Rublev specializes in historical pigments. I can't recommend their Lead tin orange either, as it turned brownish in the jar. I'd never quite trusted it enough to ever use it in a painting because I'd never heard of its historical use beyond glass work. I've found some of their lead whites very good though.

Williamsburg still supplies a zinc white and a titanium and zinc white in the 150ml but they've removed zinc white from their pre-mixed colours.

Gigalot
03-31-2019, 04:12 AM
Hi Gigalot -
Yes, I know you are a chemist. That is why I read your posts with great attention. :)

The main problem isn't in Zinc White, it comes with Lead. Lead is toxic and and became rare. We need to replace it to more comfortable white paint. Massive attacks on Zinc can't solve this problem because pure Titanium White as a replacement have some stability issues, while Zinc can help (according to recent Meclenburg opinion, but not according to present Sarah Sands position!) to solve most of Titanium White troubles.

You can also read Robert Gamblin's article:
https://gamblincolors.com/zincoxideinartistoilcolors/

Gigalot
03-31-2019, 04:18 AM
Williamsburg still supplies a zinc white and a titanium and zinc white in the 150ml but they've removed zinc white from their pre-mixed colours.
I do not trust Williamsburg zinc-free paints. They can develop some other stability issues over time. They have very short testing time. That time isn't enough to even evaporation of natural plasticizers and not enough to complete drying processes into oil paint films. I do not trust much the result of any short tests. For example, their umber, titanium and cobalt blue are in ideal conditions in comparison with Zinc White. But such paints are well known to have solvent solubility degradation issues, cracks or develop excessive weakness.

Dana Design
03-31-2019, 01:12 PM
I am very happy to see a civilized debate here sharing information...whether one agrees or not, we all learn something.
Moderators do not remove posts as a matter of policy as the remaining posts would make no sense to the reader. Onward and upwards! Please continue!

plnelson
03-31-2019, 02:35 PM
The main problem isn't in Zinc White, it comes with Lead. Lead is toxic and and became rare. We need to replace it to more comfortable white paint. Massive attacks on Zinc can't solve this problem because pure Titanium White as a replacement have some stability issues, while Zinc can help (according to recent Meclenburg opinion, but not according to present Sarah Sands position!) to solve most of Titanium White troubles.

You can also read Robert Gamblin's article:
https://gamblincolors.com/zincoxideinartistoilcolors/

I asked you for documentation on Mecklenburg's change in heart and you referred me to Sarah Sands which I linked to including a communication she had from Mecklenburg in 2018 which is very recent and which did not support the idea that he had a change of heart.

Mecklenburg is one of the few objective sources here because he's with Smithsonian and not with a paint manufacturer. The paint manufacturers who sell lead paint like Rublev and Williamsburg have posted the strongest anti zinc articles.

But to quote the Gamblin article, it says, "as a general rule avoid zinc white as a mixing white". And as I mentioned elsewhere in this thread I had a long conversation with them on Friday about this exact article and they admitted that none of their whites have the transparency of zinc white. The closest they could suggest was their 1980 student grade transparent white. I bought some yesterday but when I opened the cap to try to squeeze out some paint I got nothing but oil because apparently it had separated in the tube!! So now I either have to figure out how to remix it or return this tube to the store and get another one. I've occasionally seen this before but usually only with very cheap paints.

Gigalot
03-31-2019, 05:25 PM
The closest they could suggest was their 1980 student grade transparent white. I bought some yesterday but when I opened the cap to try to squeeze out some paint I got nothing but oil because apparently it had separated in the tube!
Put this paint pill on absorbent paper to remove excessive oil content. That helps

WFMartin
03-31-2019, 08:58 PM
I usually tend to be quite opinionated regarding topics such as this. However, regarding the use of Zinc White I am rather center-of-the-road. While I am not absolutely paranoid regarding the use of Zinc White because of the evidence regarding cracking, and delaminating, I also DO tend to avoid it (because of that evidence).

My gut feeling (similar to the lightfastness of various colors), is that if used with other color, and in other mixtures, Zinc White will probably not exhibit the drastic cracking, and delaminating that is attributed to it.

However, just as with genuine Alizarin Crimson, I will continue to avoid using Zinc White. If I obtain a tube of Flake White, or Permalba White whose ingredients indicate some Zinc White, I will not panic, nor will I expect my painting to delaminate from its substrate.

But, the evidence seems quite clear that Zinc White will exhibit some form of weakness that is inherent in Zinc White. But, I do not believe that my painting will fail if I use a White that contains some Zinc White, mixed with some Titanium, or some Lead Carbonate. Most of those sort of tests (such as lightfastness of Alizarin Crimson, or delaminating tendencies of Zinc White) are conducted on pure, specific pigments, and most of us oil painters seldom use any sort of paint in its pure form; we nearly always mix it with something else, including our chosen painting medium.

sidbledsoe
03-31-2019, 11:33 PM
Mecklenburg is one of the few objective sources here because he's with Smithsonian and not with a paint manufacturer.
I have learned through direct experience that this is not a certainty.
Researchers often have their own agendas that sometimes are not objective, such as when they are desperate to make a name for themselves as the "discoverer", the
"revealer", or the first to "identify" a previously unknown problem.

plnelson
04-01-2019, 12:00 AM
I have learned through direct experience that this is not a certainty.
Researchers often have their own agendas that sometimes are not objective, such as when they are desperate to make a name for themselves as the "discoverer", the
"revealer", or the first to "identify" a previously unknown problem.

But you could say that about anyone in which case why should we take any scientist seriously? There's no particular reason to assume that Mecklenburg is anything but an objective source whereas the conflict of interest that a paint manufacturer might have is more obvious. I am a member of the AAAS; we're the people who publish the journal Science, and we require authors to reveal any funding sources or other potential conflicts of interest for that reason.

Few of us have the background in physical chemistry or scientific resources to do meaningful tests, and the time scale we operate on is too short to show many effects. Earlier in this thread I posted an image of an older painting of mine which heavily uses zinc white and is on canvas which is considered a worse case, and so far there's no sign of cracking, but I certainly wouldn't regard that one example as evidence of anything, whereas some others here would take it as proof positive that there is no problem with zinc white.

Ron Francis
04-01-2019, 01:13 AM
I like your level headed posts plnelson.

Although I have posted warnings about zinc here, I also have anecdotal evidence in it's favour.
I did a painting around 17 years ago that I recently destroyed.
I used either W&N flake white, or Art Spectrum titanium, I can't remember which.
Both contain an unknown quantity of zinc, so either way, the painting had zinc in it.
I bent parts of the painting back on itself 180 degrees, unsuccessfully trying to get it to crack or delaminate.
Zinc can act quite quickly to make paint brittle, so I thought 17 years was significant, but it is still very young in the life of a painting.
I also wouldn't regard this as proof of anything, but I was quite heartened by it in relation to my own work.

Raffless
04-01-2019, 05:29 AM
There s no concrete answers here. Just brittle ones 😏

Gigalot
04-01-2019, 08:41 AM
There s no concrete answers here. Just brittle ones 😏
Try eggshell white in linseed oil. It is easy to prepare and to use for glazing or to mix translucent colors. Zinc is good for people who use it thinly or in small quantities. :)

capnd
04-01-2019, 12:31 PM
Well, for my part I've decided to make the move back away from lead and get my transparancy from zinc. I'll miss the luminance and dry time of lead, that's about it. For my supports, I'll also stop lead priming my own. Just bought some Claessens linen - and they now use zinc in layer 1. With that said - I will mount my linen to bb panels - not stretchers - not because I am afraid to stretch zinc canvas, but because I like the firmess of painting on panels ... and rarely go to a size where the panels get so big that the weight is unmanageable. Regardless of whether claessens were forced to go to zinc, I think it's time we start giving the EU paint and canvas folks the benefit of their expertise.

Gigalot
04-01-2019, 02:21 PM
Well, for my part I've decided to make the move back away from lead and get my transparancy from zinc..
Pay attention on modern oil painting mediums, based on acrylic MSA or you can add water based acrylic mediums (Synvar; Lukas Medium-3) into oil paint (at least, I do that). Acrylic resin is flexible and non-reactive with Zinc white. It gives enough flexibility to Zinc White.
Watch https://www.youtube.com/watch?v=YUM4QQqs84o and add acrylic to Zinc White! :lol:

plnelson
04-01-2019, 09:08 PM
So, I suggest the Rossol book “The Artist’s Complete Health and Safety Guide.”

Deb the details devil
Thanks for suggesting the Rossol. I got it through interlibrary loan. The book is trying to cover too much territory for 400 pages so it skims over details. There is nothing about lead or cadmium specifically as used in paint; just generic information about the metals themselves, like you could find on Wikipedia. There is a "pigments" chapter but that's for safe practice when working with literal pigments, i.e., in powder form, e.g., use of a glove box, protective clothing, etc. The table in that chapter references the generic table for toxicity information.

They're trying to cover ALL the arts from pottery to papermaking to textiles to glass-blowing, so painting just gets a side glance, lumped in with drawing. So I still don't have a basis to compare cadmium to lead paint. BUT...
... there were some interesting points:
1. Lead CAN be absorbed through the skin: "Lead metals, lead oxide, and lead nitrate are known to absorb through the skin. Other compounds probably can absorb as well." I assume by "other compounds" the author is including lead carbonate, but this is where a little more focus on art materials would be helpful given that it calls itself an "Artists Complete Guide".

I paint in gloves anyway but I've seen artists say lead is only a danger if ingested, and Rossol disagrees.

Elsewhere in the book Rossol makes another point about skin absorption, saying the skin absorption of other metals is, "unstudied and unknown. But, given the studies of lead,the assumption that other metals do not skin-absorb is unwarranted at this time." which undermines shibboleth that you can't absorb cadmium, cobalt or chromium paint through your skin.

2. Rossol says this about cadmium: "Some cadmium compounds are insoluble in acid, but solubility is not directly related to bioavailability. All cadmium compounds should be considered highly toxic."
... this flies in the face of the widespread view here on WC that some smart boffins have devised a way to lock up the toxicity of cadmium while letting those bright colours still shine through.

sidbledsoe
04-01-2019, 09:50 PM
But you could say that about anyone in which case why should we take any scientist seriously? There's no particular reason to assume that Mecklenburg is anything but an objective source whereas the conflict of interest that a paint manufacturer might have is more obvious. I am a member of the AAAS; we're the people who publish the journal Science, and we require authors to reveal any funding sources or other potential conflicts of interest for that reason.

You deemed the report an objective one that is completely clear of any bias, I pointed out one single possible reason for bias. That isn't a condemnation of all scientists, it is merely a statement of fact.
The last report I have heard is that the Mecklenberg study on zinc on the Natural Pigment site is not a published report, but Brian may know more about that.

sidbledsoe
04-01-2019, 09:58 PM
It does beg the question, if ultimate permanence is the goal, why does Rublev sell genuine vermilion, which has a demonstrable lack of lightfastness and permanence issues, among other dubious pigments? And boy do they think it's just dandy! :lol: Why does Willamsburg sell genuine alizarin crimson? I suspect the justification for those colors still being used is equally applicable to zinc white's continued use, yet their demonization has not reached the "friends don't let friends…" level of hysteria and marketing. They all fall under the umbrella of pigments not performing well in lab tests, and having known problems to conservators, yet on the whole not exhibiting the purported issues in real world use.
You left out stuff that Rublev sells such as genuine rabbit skin glue and a raft of materials for making genuine traditional gesso, both of which I believe Mecklenberg claims is one of the sources of cracking in oil paintings, (with no zinc required).

RomanB
04-02-2019, 02:26 AM
You left out stuff that Rublev sells such as genuine rabbit skin glue and a raft of materials for making genuine traditional gesso, both of which I believe Mecklenberg claims is one of the sources of cracking in oil paintings, (with no zinc required).

Relative humidity and temperature variations are the source, not rabbit skin glue. Animal glues are still superior in the long run to other alternatives such as emulsion grounds, PVA or acrylic sizes and fake gessoes.

Gigalot
04-02-2019, 02:50 AM
You left out stuff that Rublev sells such as genuine rabbit skin glue and a raft of materials for making genuine traditional gesso, both of which I believe Mecklenberg claims is one of the sources of cracking in oil paintings, (with no zinc required).
They are just snobs, Sid. Chemical and UV light stability of modern acrylic polymers are better than of collagen glues. And the main problems of collagen glues is poor flexibility when use on canvas, while acrylic can give superior flexibility. The only sturgeon fish glue is more or less trusted thing, but nowadays, there are more artists in Russia than sturgeons. :lol:

Ron Francis
04-02-2019, 06:41 AM
Relative humidity and temperature variations are the source, not rabbit skin glue. Animal glues are still superior in the long run to other alternatives such as emulsion grounds, PVA or acrylic sizes and fake gessoes.
What evidence do you have to support the claim that animal glues are superior? Being hygroscopic is certainly a weakness.

RomanB
04-02-2019, 10:42 AM
What evidence do you have to support the claim that animal glues are superior? Being hygroscopic is certainly a weakness.

Animal glues remain resoluble for centuries and this property makes them self-healing to some extent. As far as I know, of modern synthetic polymers only high molecular weight Aquazol is close to animal glues in properties. However, Aquazol takes relatively too much water, could flow after ageing and stinks. Canvases sized with animal glues are re-stretched after each seasonal cycle of RH change. That's why it was possible to use canvas strainers without stretching keys. On wooden panels it behaves even better: Fayum mummy portraits has sizings made of animal glue.

Sizes made with acrylic polymers or PVA are non-reversible and non self-healing in ambient conditions. They form "dead" films that do not re-stretch with changes of RH. There is no mechanism to reverse adhesion problems.

Acrylic sizes and primings became standard options not because of their superior longevity, but because they are simpler to be made industrially and to be sold at stores.

plnelson
04-02-2019, 12:14 PM
Relative humidity and temperature variations are the source, not rabbit skin glue. Animal glues are still superior in the long run to other alternatives such as emulsion grounds, PVA or acrylic sizes and fake gessoes.
JustPaint (Sarah Sands) says that RSG expands and contracts as much as 4% due to environmental factors where is acrylic gesso is only 1.5%. This contributes to cracking on paintings even when there's no zinc involved (This thread is about zinc). Since most of us don't live in environmentally controlled environments, or have any control over where our paintings are hung by buyers, the superior material in practice is the one that does not respond as much to changes in temperature or humidity.

RomanB
04-02-2019, 12:25 PM
the superior material in practice is the one that does not respond as much to changes in temperature or humidity.

The superior material is one that self-repairs. Acrylic dispersion lacks such property.

plnelson
04-02-2019, 12:37 PM
The superior material is one that self-repairs. Acrylic dispersion lacks such property.
Cracks in paint don't self-repair even if the underlying RSG does. The research quoted in the JustPaint articles on this cited expansion and contraction of RSG layers as a significant contributor to cracking in painting even when there was no zinc involved.

Gigalot
04-02-2019, 12:48 PM
I can agree with plnelson. There are several coating materials, Urethane, Epoxy, Alkyd and Acrylic resins. The most flexible, most lightfast and less yellowish is acrylic polymer. Most stable exterior paints are made from acrylic dispersion.
Oil paint or hide glue can't reach the same stability. Acrylic primer is the only one flexible material, that can be used on canvas without having risk of cracks.
However, if you like, you can make a size with gelatin glue and then use acrylic dispersion on top of it. RSG or gelatin are good in museum conditions with stable and optimal RH. In humid climate, RSG is disastrous material. However, snobs can use what they like more. But as for me, I use Acrylic gesso about ten years of my painting history. Other artists used Acrylic during last six decades with only superior results.

AnnieA
04-02-2019, 01:06 PM
Thanks for suggesting the Rossol. I got it through interlibrary loan. The book is trying to cover too much territory for 400 pages so it skims over details. There is nothing about lead or cadmium specifically as used in paint; just generic information about the metals themselves, like you could find on Wikipedia. There is a "pigments" chapter but that's for safe practice when working with literal pigments, i.e., in powder form, e.g., use of a glove box, protective clothing, etc. The table in that chapter references the generic table for toxicity information.

They're trying to cover ALL the arts from pottery to papermaking to textiles to glass-blowing, so painting just gets a side glance, lumped in with drawing. So I still don't have a basis to compare cadmium to lead paint. BUT...
... there were some interesting points:
1. Lead CAN be absorbed through the skin: "Lead metals, lead oxide, and lead nitrate are known to absorb through the skin. Other compounds probably can absorb as well." I assume by "other compounds" the author is including lead carbonate, but this is where a little more focus on art materials would be helpful given that it calls itself an "Artists Complete Guide".

I paint in gloves anyway but I've seen artists say lead is only a danger if ingested, and Rossol disagrees.

Elsewhere in the book Rossol makes another point about skin absorption, saying the skin absorption of other metals is, "unstudied and unknown. But, given the studies of lead,the assumption that other metals do not skin-absorb is unwarranted at this time." which undermines shibboleth that you can't absorb cadmium, cobalt or chromium paint through your skin.

2. Rossol says this about cadmium: "Some cadmium compounds are insoluble in acid, but solubility is not directly related to bioavailability. All cadmium compounds should be considered highly toxic."
... this flies in the face of the widespread view here on WC that some smart boffins have devised a way to lock up the toxicity of cadmium while letting those bright colours still shine through.

I've been reading this thread with interest and want to thank Deb and pinelson for the information from Rossoi, which only strengthens my resolve not to use lead-based paint. I'm going to struggle with cadmiums. I've purchased cadmium paints at some incredible prices (craigslist/other sales) and now have quite a stock of them. But I will be more diligent in my use of gloves based on the info you two have provided. Can either of you tell me when was the Rossoi book written?

One thing I'm wondering about is why paint manufacturers don't try some of the other white pigments that are very or at least somewhat transparent. I checked just the first part of the section on whites in the Color of Art Database, and there are really quite a few pigments that are listed as at a 2 or even 3 in transparency (with 4 being the most transparent; zinc white is rated at 2). There are many of them for which the pigment is available to artists for purchase (mostly from Kremer Pigments, but also Natural Pigments and Schminke - and there may be others). In checking this, I didn't even get to the whites that have CI numbers. http://www.artiscreation.com/white.html#.XKOMJS-ZM1g
It seems to me that some manufacturer could make a fortune by offering a reasonably priced fairly transparent white paint that doesn't have the potential drawbacks of either lead or zinc. Except for Holbein's Ceramic White (Strontium Titanate) and Williamsburg's Porcelain White (Lithopone), there don't seem to be any manufacturers making alternative whites, and those are too expensive for everyday use.

Gigalot
04-02-2019, 01:39 PM
There are many of them for which the pigment is available to artists for purchase (mostly from Kremer Pigments, but also Natural Pigments and Schminke - and there may be others). In checking this, I didn't even get to the whites that have CI numbers. http://www.artiscreation.com/white.html#.XKOMJS-ZM1g
It seems to me that some manufacturer could make a fortune by offering a reasonably priced fairly transparent white paint that doesn't have the potential drawbacks of either lead or zinc. Except for Holbein's Ceramic White (Strontium Titanate) and Williamsburg's Porcelain White (Lithopone), there don't seem to be any manufacturers making alternative whites, and those are too expensive for everyday use.
https://www.kremer-pigmente.com/en/fillers-und-building-materials/colorless-und-colored-mineral-fillers/plaster-blanc-fixe-and-others/1903/blanc-fixe

Red 9
04-02-2019, 02:08 PM
I've been reading this thread with interest and want to thank Deb and pinelson for the information from Rossoi, which only strengthens my resolve not to use lead-based paint. I'm going to struggle with cadmiums. I've purchased cadmium paints at some incredible prices (craigslist/other sales) and now have quite a stock of them. But I will be more diligent in my use of gloves based on the info you two have provided. Can either of you tell me when was the Rossoi book written?

One thing I'm wondering about is why paint manufacturers don't try some of the other white pigments that are very or at least somewhat transparent. I checked just the first part of the section on whites in the Color of Art Database, and there are really quite a few pigments that are listed as at a 2 or even 3 in transparency (with 4 being the most transparent; zinc white is rated at 2). There are many of them for which the pigment is available to artists for purchase (mostly from Kremer Pigments, but also Natural Pigments and Schminke - and there may be others). In checking this, I didn't even get to the whites that have CI numbers. http://www.artiscreation.com/white.html#.XKOMJS-ZM1g
It seems to me that some manufacturer could make a fortune by offering a reasonably priced fairly transparent white paint that doesn't have the potential drawbacks of either lead or zinc. Except for Holbein's Ceramic White (Strontium Titanate) and Williamsburg's Porcelain White (Lithopone), there don't seem to be any manufacturers making alternative whites, and those are too expensive for everyday use.



Holbein also has a "Permanent White" which is Titanium White and Barium. According to Holbein, the Barium helps mitigate some of the yellowing and adds transparency. Holbein makes extremely nice paint, in my opinion.



Personally, I am really loving Williamsburg's pure titanium white in safflower mixed with a little bit of stand oil and spike lavender. I've done a comparison next to lead white and the warmth and transparency are darn near equal. Only downside of course is that it makes the paint a little more fluid. I also keep some pure zinc in walnut oil on hand for glazing (you just can't beat it for glazing and scumbling!)

sidbledsoe
04-02-2019, 04:29 PM
Relative humidity and temperature variations are the source, not rabbit skin glue. Animal glues are still superior in the long run to other alternatives such as emulsion grounds, PVA or acrylic sizes and fake gessoes.
yes I know it is humidity that fluctuates and the source of humidity is water vapor and the source of the fluctuation is the earth's weather cycle, etc.
It is simply the double standard that I was pointing out.
I have and use rabbit skin glue, sometimes for art, often for woodworking and violin/guitar repairing/building.
Humidity fluctuates significantly, and we simply can't keep every painting we make and sell in a controlled environment.

AnnieA
04-02-2019, 04:50 PM
https://www.kremer-pigmente.com/en/fillers-und-building-materials/colorless-und-colored-mineral-fillers/plaster-blanc-fixe-and-others/1903/blanc-fixe
Hey, Alex, I don't really understand why you linked that. I was talking about the lack of transparent zinc white alternatives in manufacturers' tube paints, as I don't want to make my own. Is there something I'm missing?

Holbein also has a "Permanent White" which is Titanium White and Barium. According to Holbein, the Barium helps mitigate some of the yellowing and adds transparency. Holbein makes extremely nice paint, in my opinion.

Personally, I am really loving Williamsburg's pure titanium white in safflower mixed with a little bit of stand oil and spike lavender. I've done a comparison next to lead white and the warmth and transparency are darn near equal. Only downside of course is that it makes the paint a little more fluid. I also keep some pure zinc in walnut oil on hand for glazing (you just can't beat it for glazing and scumbling!)
OK, Red, I missed that Holbein paint as another alternative. Holbein does indeed make good paints; have you tried their Permanent White? Anybody? The WB Titanium white + stand + spike lavender probably wouldn't work so well for me as I like to paint somewhat thickly.

Red 9
04-02-2019, 08:08 PM
Hey, Alex, I don't really understand why you linked that. I was talking about the lack of transparent zinc white alternatives in manufacturers' tube paints, as I don't want to make my own. Is there something I'm missing?


OK, Red, I missed that Holbein paint as another alternative. Holbein does indeed make good paints; have you tried their Permanent White? Anybody? The WB Titanium white + stand + spike lavender probably wouldn't work so well for me as I like to paint somewhat thickly.


Negative. I'm tempted to try it though since it's fairly economically priced for the safflower version. The only thing holding me back is I don't know much about Barium Sulphate's long-term effects when used as filler. Anybody know?

Gigalot
04-02-2019, 10:04 PM
Negative. I'm tempted to try it though since it's fairly economically priced for the safflower version. The only thing holding me back is I don't know much about Barium Sulphate's long-term effects when used as filler. Anybody know?
Barium Sulphate is insoluble and chemically inner substance.

plnelson
04-02-2019, 11:53 PM
Barium Sulphate is insoluble and chemically inner substance.
Barium sulfate for many years was a very popular radiocontrast agent for gastrointestinal x-rays. If you've ever had an upper GI or lower GI x-ray or CT scan with contrast you've probably chugalugged liters of barium sulfate.

AnnieA
04-03-2019, 02:51 AM
Holbein also has a "Permanent White" which is Titanium White and Barium. According to Holbein, the Barium helps mitigate some of the yellowing and adds transparency. Holbein makes extremely nice paint, in my opinion.
I just looked up Holbein Permanent White on the Blick site and all that's listed for the pigment is Titanium White. I guess that the Barium, because it's considered a filler, isn't required to be indicated. But what seems confusing is that there's a Permanent White EX and a Permanent White SF. I wondered about what the difference is between them, quso here's what the Holbein site says:
Permanent White **** A titanium white with the same general handling qualities but with a barium sulphate additive which inhibits yellowing in early drying while reducing tinting power and increases transparency. Available in two variations: Permanent White SF is produced using poppy oil, while Permanent White EX is produced using safflower oil.
The description on the Holbein site about the differences between their whites is particularly well done, I thought: http://www.holbeinartistmaterials.com/artist-oil-color-2/#whites
Thanks for alerting me to their Permanent White. I'm curious about whether the formulation with either poppy or safflower will create a strong paint film, so I may do some more research before making a purchase. The price is certainly a lot better than their Ceramic White - about a third less.

Raffless
04-03-2019, 05:17 AM
Barium sulfate for many years was a very popular radiocontrast agent for gastrointestinal x-rays. If you've ever had an upper GI or lower GI x-ray or CT scan with contrast you've probably chugalugged liters of barium sulfate.

I remember it was referred to as a Barium meal.:)

Dcam
04-03-2019, 09:50 AM
I got that test years ago Raff because I was way too scared to get tube-down-throat. UGH. It tasted awful, but I was awake and aware.

ALSO.......
Holbein Ceramic White contains titanium and strontium pigment which will not react with sulfur. Ceramic White offers superior surface strength without brittleness, increases tinting and covering power over lead and zinc, but when compared to titanium white, it offers increased transparency, drying time and visual whiteness. Excellent handling qualities.

Red 9
04-03-2019, 10:17 AM
I just looked up Holbein Permanent White on the Blick site and all that's listed for the pigment is Titanium White. I guess that the Barium, because it's considered a filler, isn't required to be indicated. But what seems confusing is that there's a Permanent White EX and a Permanent White SF. I wondered about what the difference is between them, quso here's what the Holbein site says:

The description on the Holbein site about the differences between their whites is particularly well done, I thought: http://www.holbeinartistmaterials.com/artist-oil-color-2/#whites
Thanks for alerting me to their Permanent White. I'm curious about whether the formulation with either poppy or safflower will create a strong paint film, so I may do some more research before making a purchase. The price is certainly a lot better than their Ceramic White - about a third less.



I like safflower. Decent drying rate and from what I've read it creates a slightly stronger film than poppy. Than again, poppy has been used for a lot longer. The poppy oil version of Permanent White (SF) is $4 more; not worth it in my opinion.

Gigalot
04-03-2019, 10:18 AM
Calcium carbonate medium can also be useful.