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chamisa
02-19-2019, 09:21 AM
I am wondering if instead of buying expensive Gamblin oil grounds, you can just use cheap Winton oil paint with a tiny bit of turps or a lot of Liquin for faster drying grounds than using the Gamblin oil grounds - which I do like, but it takes forever to dry.

And considering how quickly Liquin drys, couldnít you just put a layer of Liquin
on panel or canvas, let it dry, and youíd have less absorbency?
Thanks

Trikist
02-19-2019, 09:44 AM
What works easiest and most cheaply for me is to cover the absorbent gesso with a thin layer of acrylic matte medium. You get plenty of grab from the texture without the sinking in of the paint. Gary

Gigalot
02-22-2019, 12:36 AM
White acrylic paint layer on top of wrong quality gesso is also useful. It solves absorbency trouble.

JCannon
02-22-2019, 02:42 AM
Buy "Mona Lisa" brand panels. Those things are like Teflon. Seriously, they should make cookware.

chamisa
02-22-2019, 08:22 AM
I thought ALL acrylic gesso was too absorbent?
What brands are considered non absorbent?

Iím still curious if you can use Liquin as a ground?
Iím going to try it today on some gessoed panels I know are too absorbent as an experiment. I donít use it as a medium anymore and have some leftover.

Gigalot
02-22-2019, 09:57 AM
I thought ALL acrylic gesso was too absorbent?
What brands are considered non absorbent?

Acrylic gesso is absorbent because of too much filler content. Acrylic polymer dispersion and regular acrylic paint has much less absorbency than overloaded with filler acrylic gesso. Use ACRYLIC PAINT instead when you want less absorbency.
A mixture made with 2/3 acrylic primer + 1/3 white acrylic paint gives medium absorbency.

Richard P
02-22-2019, 12:09 PM
Silica as a filler in clear gesso doesn't seem as absorbent as calcium carbonate and other fillers used in white gesso.

chamisa
02-22-2019, 12:30 PM
Acrylic gesso is absorbent because of too much filler content. Acrylic polymer dispersion and regular acrylic paint has much less absorbency than overloaded with filler acrylic gesso. Use ACRYLIC PAINT instead when you want less absorbency.
A mixture made with 2/3 acrylic primer + 1/3 white acrylic paint gives medium absorbency.

Do you mean acrylic paint for a ground that you buy at the paint store or art acrylics?

Thanks

RomanB
02-22-2019, 12:35 PM
Silica as a filler in clear gesso doesn't seem as absorbent as calcium carbonate and other fillers used in white gesso.

Silica mixed with oil will promote its yellowing in the long run. It acts as a catalyst for coloured contaminants. I saw old samples of silica ground with oil in 1966 - they are dark brown now.

Gigalot
02-22-2019, 12:43 PM
Do you mean acrylic paint for a ground that you buy at the paint store or art acrylics?

Thanks
I use China Maries artists acrylic paint. It has high polymer content and improved flexibility (less pigment more polymer!)

Richard P
02-22-2019, 12:43 PM
I was referring to acrylic gesso using silica Roman.

Gigalot
02-22-2019, 12:47 PM
Silica mixed with oil will promote its yellowing in the long run. It acts as a catalyst for coloured contaminants. I saw old samples of silica ground with oil in 1966 - they are dark brown now.
:clap: :clap: Zinc whte content can reduce oil darkening. I guess, only Zinc can do that. Finely refined and sun bleached linseed oil + small amount of Zinc White can do the job...

RomanB
02-22-2019, 01:52 PM
Finely refined and sun bleached linseed oil + small amount of Zinc White can do the job...

The job of cracking paint film before it will have a chance to yellow considerably? ;-) By the way, in the same source where I saw silica ground in oil there are many other paint tests, including various Zinc Whites. A few observations:

1. After about 50 years the less yellowed are Zinc White samples made with pentaerythritol esters of sunflower and cottonseed fatty acids, so-called "penta-oil". Also they have different pattern of cracks than other drying oil binders.

2. Only samples which were stored in light cracked significantly. Samples that were stored in darkness are almost without any cracks. I don't know how to explain this.

Gigalot
02-23-2019, 01:39 AM
so-called "penta-oil"
/QUOTE]
Pentol, the Russian patented technology to make a replacement for Linseed oil. I had read that patent (1949Year) several years ago when studied metal-free degradation and final decomposition of oil paint films. I have a few "Penta" tubes, they are no longer in production. I guess, that pentol was replaced with extra finely refined linseed oil....
[QUOTE=RomanB]
2. Only samples which were stored in light cracked significantly. Samples that were stored in darkness are almost without any cracks. I don't know how to explain this.
Light induced polymer degradation. It is well known thing in polymer industry. Light can shorten polymer molecule chains and also can make excessive cross-linkage. Itself, sunflower and safflower oil can't polymerize to enough high molecular weight molecles. Finally, well-dried polymer will lost plasticizer and become extremelly brittle.

RomanB
02-23-2019, 02:45 AM
Pentol, the Russian patented technology to make a replacement for Linseed oil. I had read that patent (1949Year) several years ago when studied metal-free degradation and final decomposition of oil paint films. I have a few "Penta" tubes, they are no longer in production. I guess, that pentol was replaced with extra finely refined linseed oil

Do you have the patentís number? I thought they started to produce pentol only in 1960-s.

Gigalot
02-23-2019, 03:40 AM
Do you have the patentís number? I thought they started to produce pentol only in 1960-s.
I just forgot patent number.:crying:
Pentaerythrytol was introduced to paint industry soon after the WWII because people needed to utilize stored large quantities of it that was prepared for use to make high explosives.

Dehydrated Castor Oi is another fast drying product. Unfortunatelly, many od synthetic drying oils are extremely yellowish and finely refined linseed oil is much better.

RomanB
02-26-2019, 05:12 PM
Pentol, the Russian patented technology to make a replacement for Linseed oil. I had read that patent (1949Year) several years ago when studied metal-free degradation and final decomposition of oil paint films. I have a few "Penta" tubes, they are no longer in production. I guess, that pentol was replaced with extra finely refined linseed oil....


Was it SU67618A1 (http://patents.su/patents/67618-sposob-izgotovleniya-zamenitelya-lnyanogo-masla-1.png)?

Gigalot
02-27-2019, 04:45 AM
Was it SU67618A1 (http://patents.su/patents/67618-sposob-izgotovleniya-zamenitelya-lnyanogo-masla-1.png)?
Exactly what I mentioned! So it was 1946 year...

Carl Kreul and Art Creation используют Рыжиковое масло. I think so.

AnnieA
02-27-2019, 03:14 PM
I took a workshop this past weekend with an excellent portrait/figure painter. He described his method for preparing store-bought canvases which were already coated with the manufacturer's gesso.

He mixes Titanium White oil paint with marble dust and barium sulfate and paints this mixture over the gesso already on the canvas. He says this approach yields a surface that still grabs the paint, but isn't excessively absorbent as gesso alone can too often be. It sure sounded easier than starting from scratch.

The first day of the class I had brought a canvas that was way too absorbent and the paint wasn't sticking, making the entire process a horrible struggle. I didn't have all the ingredients to use his method, but that evening prepared a store-bought canvas (to use the second day of the workshop) by applying a mixture of a quick-drying white with a little raw umber and ultra blue added in to give a medium gray tone. When I used it the next day, I couldn't believe how much it helped! I'm thinking the absorbancy of my canvases may be one reason why I've been such a slow painter - I was taking a lot of time struggling just to get the paint to stick!

Note that he also said that he typically uses lead as his white. I'm not clear on why he mentioned titanium instead in the mixture described above.

Gigalot
02-28-2019, 01:53 AM
I took a workshop this past weekend with an excellent portrait/figure painter. He described his method for preparing store-bought canvases which were already coated with the manufacturer's gesso.

He mixes Titanium White oil paint with marble dust and barium sulfate and paints this mixture over the gesso already on the canvas. He says this approach yields a surface that still grabs the paint, but isn't excessively absorbent as gesso alone can too often be. It sure sounded easier than starting from scratch.

The first day of the class I had brought a canvas that was way too absorbent and the paint wasn't sticking, making the entire process a horrible struggle. I didn't have all the ingredients to use his method, but that evening prepared a store-bought canvas (to use the second day of the workshop) by applying a mixture of a quick-drying white with a little raw umber and ultra blue added in to give a medium gray tone. When I used it the next day, I couldn't believe how much it helped! I'm thinking the absorbancy of my canvases may be one reason why I've been such a slow painter - I was taking a lot of time struggling just to get the paint to stick!

Note that he also said that he typically uses lead as his white. I'm not clear on why he mentioned titanium instead in the mixture described above.
I am sure, that 99% of such experiments are disastrous...

AnnieA
02-28-2019, 02:54 AM
I am sure, that 99% of such experiments are disastrous...
I am sure, that 99% of such experiments are disastrous...
Experiment? He's a well-known painter...

Why do you say that, Alex?

Gigalot
02-28-2019, 07:55 AM
Experiment? He's a well-known painter...

Why do you say that, Alex?
Joshua Reynolds was even more well-known painter... I said, that experiments with gesso formulation can be very dangerous for painting. Hope, people know what they are doing and why.

AnnieA
02-28-2019, 11:04 AM
Joshua Reynolds was even more well-known painter... I said, that experiments with gesso formulation can be very dangerous for painting. Hope, people know what they are doing and why.
The process that I described was not to make a gesso, but to add a layer of white oil paint/marble dust/barium sulfate to intervene when the existing manufacturer's gesso on a store-bought canvas is too absorbent.

Marble dust is frequently used in impasto mediums for oil painting, barium sulfate is widely used as an extender in oil paints, and of course the use of titanium white paint is widespread too. Since all the ingredients of this mixture have been commonly used for a long time, I don't see why there should be any problem when they're used as I described earlier.

Can you explain, Alex, where you think any specific potential problem may lie?

Gigalot
02-28-2019, 01:21 PM
Can you explain, Alex, where you think any specific potential problem may lie?
The main trouble as I know are almost always "drying issues". Oil primer can cause "floating cracks" when it is not dried well. Therefore, I use specific acrylic primer and I always try to make it well cured.. As possible... "How to shorten drying time" is a main question of thousand people on WC. You can understand the result of such kind of experiments! :lol:

AnnieA
02-28-2019, 03:37 PM
So are you saying there are likely to be drying problems with this method? Isn't this really a form of imprimatura? I haven't heard of problems with imprimaturas, and the primary difference here is it is a consistent layer painted over the entire surface.It would seem to me that as long as the subsequent paint applied was fatter, there wouldn't be a problem. Or is there something else at issue?

DebWDC
02-28-2019, 05:31 PM
Without more specific details on the materials, proportions used, etc., I think it would be impossible to figure out what constitutes a safe underlayer for an oil painting on canvas. Also, just because a well-respected public figure says its OK does not make it so. (For every expert there is an equal and opposite expert) Just because one of us says its ok does not make it so. Just because one of us says its not OK does not make it so. I think there is too much reliance in Wetcanvas discussions on referent authority such as old masters or famous current painters. I do not trust citing referent authority as a solid basis for good material handling. I would rather trust science and personal experience, going back a few decades and observing the painting. But that is hard to come by and harder to evaluate.

Here is a recent thread which may be useful to read, regarding the use of marble powder as an underlayer (gesso, ground, etc.) on canvas.
http://www.wetcanvas.com/forums/showthread.php?t=1461821

I personally would err on the side of caution, meaning that I would not put on a layer containing calcium or other inert material on a canvas. This is because canvas flexes and a calcium-based layer does not, or at least not to the same extent as canvas. It may also take a few years or the right conditions for the painting to crack. I know that many painters use calcium as an ingredient in oil paint which is applied to primed canvas and is fine. I suspect that it works ok because it is not an entire, cohesive layer on the canvas, or the ratio of calcium to drying oil is low, or the medium was modified with alkyd.

I think there are probably several different ways to successfully modify a primed canvas to be more absorbent or less absorbent.

BTW, what exactly is quick drying white? ingredients, brand, modified by any thinner, alkyd, etc.?
Thanks. Deb

Richard P
02-28-2019, 06:16 PM
Adding a layer of acrylic gel over the (acrylic) gesso will reduce absorbency. To add tooth you can add silica. The various clear gessos from Liquitex and W&N have this already so this works to reduce absorbency and add a tooth to the surface.

AnnieA
02-28-2019, 10:41 PM
Deb, that other thread was helpful and thanks very much. That makes a lot of sense about the flexibility issue. I think the instructor typically uses lead white, and maybe that, and/or the barium sulfate modifies the mixture toward greater flexibility somewhat??? But I have no idea really, so I'll stay away from this method.

My drying white was Sennelier's Rive Gauche Titanium White paint. Sennelier doesn't reveal the make up of these paints as apparently it's a trade secret. I purchased them for doing small plain air studies later this spring. I wouldn't ordinarily use something like this paint, but I figured it would work well enough to try to fix the gesso absorbency issue for the second study piece done in a weekend workshop, since I struggled so much with the surface on the first day.

I might add that I brought my two portrait studies home last night. It's odd, but they're both very sunk in. I may have used too much solvent in my paint on the first, as the absorbency of the surface was an issue, but in the second, I didn't. The coated surface appeared to make the paint stick appropriately. I think the sink in may have been a result of using burnt umber. The instructor said he uses BU and likes to leave his darks a little matte, but wow...my entire canvas is too matte. So I'm also going back to completely avoiding burnt umber.

Richard P's suggestion to use clear gesso sounds good, as does contumacious' mention in the other thread of using plain oil to modify the absorbancy of a surface. Thanks to both of you and I'll try those. But what about using a layer of Titanium white oil paint alone? Would that turn out too slippery?

Tad Spurgeon's putty medium contains calcium. I wonder if it contains sufficient oil so that flexibility is not an issue, or maybe it's best to use it only on canvas panels or other rigid substrates.

Gigalot
03-01-2019, 01:55 AM
Easy way is to apply low absorbent thin layer of Acrylic gesso or Acrylic paint. Acrylic is already flexible, dry faster and seal pores very well. Also, easy to apply with sponge or flat brush. Oil paint needs much time to dry, especially when you need lower absorbency. Non-dried oil paint layer absorbs oil from upper layer and it sinks. You need month or more to prepare it well.

AnnieA
03-01-2019, 02:31 AM
Easy way is to apply low absorbent thin layer of Acrylic gesso or Acrylic paint. Acrylic is already flexible, dry faster and seal pores very well. Also, easy to apply with sponge or flat brush. Oil paint needs much time to dry, especially when you need lower absorbency. Non-dried oil paint layer absorbs oil from upper layer and it sinks. You need month or more to prepare it well.
Thanks for your help, Alex. I've actually tried coating cheap canvases and panels with an additional coat of gesso, but that doesn't always solve the absorbency issue completely. I'm going to try the clear gesso approach instead. Yes, the problem on my second study with sinking in must have been because the layer of paint I applied the evening before was touch dry, but only just so. This doesn't make sense though, because sinking in doesn't always happen with alla prima work, does it? I thought it was generally a good thing or at least OK to apply new paint over still semi-wet paint.

Richard P
03-01-2019, 08:09 AM
Gesso normally seems to contain an absorbent material like calcium carbonate, where as clear gesso doesn't.

Raffless
03-01-2019, 08:15 AM
How can you tell if its 'sinking in' or just an earth colour drying very matte?

AnnieA
03-01-2019, 12:28 PM
RichardP, yes, and thanks again for the idea.

How can you tell if its 'sinking in' or just an earth colour drying very matte?
Aren't they the same thing?

Raffless
03-01-2019, 02:07 PM
RichardP, yes, and thanks again for the idea.


Aren't they the same thing?

Not as far as im aware Annie. Colours drying matte(earth colours) are not necesssrily suffering from oil being leached into the ground. Have you ever tried dibond?