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Old 10-04-2018, 07:17 PM
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Re: Technically Off-Topic

Richard....I'm not sure. Will do some research on that. I've never done it myself. I remember though some of the old freshly painted houses blazing white.
Bluing (fabric) Bluing, laundry blue, dolly blue or washing blue is a household product used to improve the appearance of textiles, especially white fabrics. Used during laundering, it adds a trace of blue dye (often synthetic ultramarine, sometimes Prussian blue) to the fabric.
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Old 10-04-2018, 08:38 PM
ntl ntl is offline
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Re: Technically Off-Topic

I use Mrs. Stewart's bluing in laundry to help keep whites whiter looking, brighter. It's non-toxic. When I was a kid, we made crystal gardens with it, using lumps of coal. IIRC, we used soft coal--directions at the website.
http://mrsstewart.com/many-uses-for-msb/
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Old 10-04-2018, 08:48 PM
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Re: Technically Off-Topic

my mother was a hairdresser and for the same reason, she applied many blue rinses to older women's white hair, it eliminates any yellowish tinge that makes white look very off white.
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Old 10-05-2018, 03:56 AM
Richard P Richard P is offline
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Re: Technically Off-Topic

So maybe we could do the same to combat the yellowing effect of oil paint if we had a very high key painting. Might look strange though.
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Old 10-05-2018, 07:32 AM
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Re: Technically Off-Topic

We are all about experimenting.....no?
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Old 10-05-2018, 12:06 PM
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Re: Technically Off-Topic

Anyone who had a "black light" knows that certain articles of clothing, especially white dress shirts, will glow under the light. That's because they fabric has UV (actual, just violet) brightening agents, probably from ordinary detergent rather than special bluing agents.

Artwork that glows in the dark has been around awhile. It's, like, grooovy man. Pass me a hit, bro.
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Old 10-05-2018, 12:45 PM
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Re: Technically Off-Topic

Quote:
Originally Posted by ntl
... Gesso has an open surface and acrylic paint has a closed surface...

...Acrylic paint on the other hand is made to have a surface that is durable, washable and less prone to weathering, meaning that oil will have a much less tenacious hold on it and be more prone to de-lamination in the future.

It's been suggested to start with an acrylic paint layer, finishing with oil. I was going to try that, so I'm glad I did find this information.
Oh no.Another common practice that's now an issue too.

I suppose that to speed things up, one could use black gesso in addition to the usual white to do a thin gesso grisalle. I don't know how detailed one could get but with very thin gesso perhaps it might be doable.

ntl: You could combine white and black gesso to create a neutral mid-gray to tone the canvas with, something I often do myself. If you try it, it's important to remember that because it's acrylic, it will dry to a darker color than when in liquid form.

Quote:
Originally Posted by RichardP
So maybe we could do the same to combat the yellowing effect of oil paint if we had a very high key painting. Might look strange though.
I can't vouch for the veracity of this, but I've read that Permalba White already has a tiny bit of blue in it. In at least two of the white tests that have been posted here in the past, it's been found to be the most white of all available whites and the least yellowing.
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Last edited by AnnieA : 10-05-2018 at 12:57 PM.
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Old 10-05-2018, 01:22 PM
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Re: Technically Off-Topic

I'm pretty sure that Alex and Einion ( a master of acrylics and other media here on WC) have said that acrylics are porous whether gesso or heavy body.

Most pigments used for acrylics are the same or similar to those used in traditional oils or watercolors, except for a few that are incompatible with the polymer emulsion binder. ... Acrylic paint becomes porous when dry, so a final application of varnish is recommended after the painting has dried for several months. POROUS.
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Old 10-05-2018, 02:33 PM
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Re: Technically Off-Topic

Quote:
Originally Posted by Dcam
I'm pretty sure that Alex and Einion ( a master of acrylics and other media here on WC) have said that acrylics are porous whether gesso or heavy body.

Most pigments used for acrylics are the same or similar to those used in traditional oils or watercolors, except for a few that are incompatible with the polymer emulsion binder. ... Acrylic paint becomes porous when dry, so a final application of varnish is recommended after the painting has dried for several months. POROUS.

:sigh: Sometimes trying to understand best painting practices feels like walking on quicksand.

It makes sense that the pigment would be the same in each case. But it does seem to me that there must be different binders used in gesso vs acrylic paint. I know gesso feels different on the brush than acrylic paint does. But yes, the advice to apply a varnish does seem to contradict the AMIEN info, unless varnish is recommended primarily for resistance to UV light and for easier cleaning.

I've been thinking of playing around with using gold acrylic paint to prime my canvas. I notice that Dan Smith makes a gold acrylic gesso, but it's over $35 for a pint, which is a little pricey for me for something I'll use rarely. Apparently Holbein makes a gold gesso too. Anyway, I hope that I'll be able to continue to use inexpensive gold acrylic paint. BTW, if anyone wants to try this, it's important to note that while using transparent paints over the gold tone results in a lovely glow, it's almost impossible to photograph a piece where this has been used. The gold in photographs appears much stronger than it does IRL.

Maybe this is a question for Golden...

Also, what do people think of asking Jess for a monthly off-topic thread? It should make it a little easier to track conversations, although it would also interrupt them at the end of the month.
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Last edited by AnnieA : 10-05-2018 at 02:49 PM.
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Old 10-05-2018, 02:56 PM
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Re: Technically Off-Topic

Annie: some get the wrong idea about an under-painting in acrylics. They don't understand that that paint goes on in thinner washes, almost like watercolor or tempera.
Also, and I think I've said it multiple times you can always put an isolation coat over the acrylic. One of the best is Liquitex Clear Gesso. It has an amazing tooth when dry.....so good, you can do pastels over it.
I have a painting I completed in the early 80s. The under-painting was done in acrylics and thicker than usual. I then covered with heavier oils. It is still fresh today and un-scrapable.


Please Read from GOLDEN: https://www.goldenpaints.com/technic...l_over_acrylic

Last edited by Dcam : 10-05-2018 at 03:01 PM.
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Old 10-05-2018, 03:11 PM
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Re: Technically Off-Topic

Golden has been studying the issue of oil over acrylic for some time. They find no cause for concern. From their "Just Paint" article regarding adhesion:

Quote:
The first round of testing GOLDEN conducted was in the mid 1990s and involved creating 10 mil drawdowns of five oil paints (Indanthrone Blue, Ultramarine Blue, Mauve Blue Shade, Cobalt Turquoise, and Cobalt Blue Deep) over three distinct types of acrylic films: GOLDEN Gesso, Heavy Body Titanium White, and a mixture of two parts Self Leveling Clear Gel to one part Fluid Titanium White. This provided examples of a matte and toothy ground, a standard acrylic paint, and a very smooth and glossy layer of a tinted acrylic medium. There were 75 samples created, with 25 on top of each of the three different coatings. The samples were done on lacquered cards and kept in moderate, ambient conditions within the Lab facilities. Adhesion tests were carried out in accordance to ASTM 3559 and a few representative samples were aggressively flexed to the point of causing substantial cracking to see if the paint could then be cleaved off with the use of a scalpel. So far there has not been even one recorded case of failure, even when the oil paints were applied over very smooth and high gloss films.

(I have put some text in bold for emphasis)

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Old 10-05-2018, 03:49 PM
Richard P Richard P is offline
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Re: Technically Off-Topic

A quick test (if you have a colour calibrated monitor). Here you have a slightly yellow white, a white, and a blue white. The pure white is slightly duller to have the same brightness as the others.

To me at first glance it appears that the blue white looks a little brighter. But I may be imagining it!

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Old 10-11-2018, 06:22 PM
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Re: Technically Off-Topic

Quote:
Originally Posted by Richard P
A quick test (if you have a colour calibrated monitor). Here you have a slightly yellow white, a white, and a blue white. The pure white is slightly duller to have the same brightness as the others.

To me at first glance it appears that the blue white looks a little brighter. But I may be imagining it!

Attachment 860100

Hi Richard
According to HSV which i just checked on my monitor the top two are showing a Value of 98.82%. Whereas the blue white you say looks brighter is showing at 100%. The increase in value albeit small perhaps explains this.
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Old 10-11-2018, 07:20 PM
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Re: Technically Off-Topic

Agreed that the bluish looks a little brighter.

Incidentally: Just a couple of weeks ago, I discovered that (depending on monitor) it may be possible to over-ride color calibration at the touch of a button. I had wondered why, when I posted an image under (what I thought was) calibrated conditions, it looked wrong. Thought perhaps the ambient lighting was the problem, since ambient wasn't according to spec. Turns out that the monitor has a button allowing the user to switch to some kind of gaming mode, where (regardless of software or *.icc profile) the screen data is processed without correction, to make it go faster. Someone had made that change, and the monitor doesn't say what mode it is in (unless you ask).
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Old 10-13-2018, 02:50 AM
Richard P Richard P is offline
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Re: Technically Off-Topic

Don't trust HSV, it treats each red, green and blue channel as equal when determining value. Where blue makes up a lot less of the brightness than green and red:

For RGB color spaces that use the ITU-R BT.709 primaries (or sRGB, which defines the same primaries), relative luminance can be calculated from linear RGB components: first convert the gamma-compressed RGB values to linear RGB, and then [2]

Y=0.2126R+0.7152G+0.0722B.

The formula reflects the luminosity function: green light contributes the most to the intensity perceived by humans, and blue light the least.
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