Sunday, June 24, 2018

Gouache Tests: Consistency, Smell, and 'Re-Wettability'


Illustrator Catherine Gura asked me some questions about the paint consistency of gouache, and I wasn't sure of the answers, so I asked her to do some tests and report back. Here's what she found:

"The test: first, I took six different brands of gouache and tested them right out of the tube. Then I placed fresh paint into full size pans and let them dry for five days, at which time I reactivated the gouache with water and painted.



The Brands 
Utrecht Designers

Materials
14 and 15 ml. tubes of gouache (Winsor and Newton)
a #6 brush so I could get a good load of paint 
and glycerin (by Rublev), vegetable source.

Glycerin and Gum Arabic Tests
I added three drops of gum arabic to a pan of Winsor and Newton gouache, and added three drops of glycerin to another pan of W and N gouache, and let them dry for five days, and reactivated them.

Results: Paint consistency
All of the gouache brands were thicker and creamier right out of the tube. With the exception of Winsor and Newton, I found it difficult to reactivate the paint: the gouache was noticeably thinner and felt like using watercolor. The W and N was thinner, too, but less resistant to rewetting.

Winsor and Newton: the original gouache cracked minimally in the pan; the pans with gum arabic and glycerin did not crack at all. The gum arabic made the gouache a little glossier; the addition of glycerin was the glossiest.

Results: Smell
Schmincke: an older tube smelled badly, the second tube was new, and had only a slight chemical smell
Holbein: no smell
Daler Rowney: slight smell
Utrecht: strong petroleum smell
M. Graham: slight chemical smell, did not smell of honey
Winsor and Newton: mild chemical smell: like school poster paint

Conclusions
• For best results, I would recommend working with gouache directly from the tube.
• If one wished to make a portable palette, one could set up pans of gouache: I would recommend W and N or Schmincke.
• Gum arabic made the gouache slightly glossier, and glycerin the glossiest, but both were thinner.
• I will continue to work with Winsor and Newton. For the price, I did not find Schmincke noticeably better than W and N, but I tested only one color.
• I would highly recommend avoiding Utrecht: the petroleum smell was awful.
• Holbein was thick and creamy.
• Winsor and Newton gouache dries with a slight sheen without any additives.


Here is my chart: I had to patch my scan together, and a photo of my paints."
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Thank you, Catherine. Check out her website
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7 comments:

PeggyB said...

Thanks for the very interesting test of gouache paints. One comment about the smell, many years ago I taught art in the public schools. I bought my poster paints in half gallon jars, usually from Dick Blick but I have no idea of the brand. After the second half gallon of blue poster paint exploded in my supply room (you have no idea. . . !!)I thought hm. Maybe the blue is unstable. Not only was it explosive, it was also the only color that would quickly form mold on the surface and around the mouth of the jar if not cleaned thoroughly. And yep, it stank. I only bought blue in pint jars after that.
Just thinking that you might actually have a different result with another color.

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Cat165 said...

James--thanks for the post, and thank you for your comments. Yes--it may just be the blue that I used. Another artist who uses gouache has not had any problem with odors with Schmincke, and finds it rewets well.

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Patricia Wafer said...

Thanks for a very helpful post. Odor can be very subjective. I hate the smell of Winsor Newton gouache and can't smell any odor with Schmincke or M. Graham which have become my favorites. Holbein is good, too but I found Da Vinci gouache inferior to all the other brands although their watercolors are not bad.

Jamie Williams Grossman said...

It is worth keeping in mind that some colors rewet much more easily than others. For example, true Cerulean and Viridian are among the colors that seem to be more problematic in that regard. Also, colors that are extremely strong, like Phthalo Blue and Phthalo Green, can yield a lot of intensity with very little wet paint. To compare one brand's Cerulean with another brand's Ultramarine, and another brand's Phthalo, or a Cerulean Hue, is a little like comparing apples to oranges. Even within the same brand, these colors will likely rewet differently from one another. A more fair way to test would be to compare only Ultramarine Blue (or some other specific color that uses the same pigment). One thing I've found interesting among gouache brands is how widely the color varies for Titanium White! Many are yellowed or grayish, and very few are a nice, bright white. When you see a bunch of them painted side by side, the differences are pretty astonishing.

Cat165 said...

Jamie: you're right if I wanted to compare pigments. My intention was to test, in essence, the binders and additives. To keep costs down, I purchased blues that were the least expensive. In reality, if I were to set up a palette of different colors, it might contain the colors that I tested, so I would have to contend with these results. Please keep in mind that this was an informal experiment.
As for odor: sense of smell varies for individuals. I know some chemically sensitive people who use gouache because they cannot tolerate oil or acrylic, so I reported on the smell of new tubes of gouache.
Thank you for your comments.
Catherine