To research the gouache video, I decided to ask manufacturers what ingredients they put in their paints. Here's what I wrote to them:
Dear _______,
I’m currently working on a new instructional DVD called "Gouache in the Wild," and I had a question.
In my research about gouache paints, I'm encountering some confusing information about the formulation of gouache. Many manufacturers claim in their advertising they use no opacifiers, chalks, fillers or other agents or "so-called adulterants" added to the pigment and binder, giving the impression that gouache is made up of solely of pure concentrated pigment and gum arabic. With an opaque pigment such as Venetian red, I can imagine that such a formulation might be possible.
But according to other information I've found, some pigments are so transparent (such as phthalocyanine and other organic pigments) that even if they are used generously in the formulation, the gouache would be unacceptably transparent and dark, and therefore whiteners or opacifiers are used to make them lighter in value and more opaque.
Other authorities claim that the formulations include other necessary ingredients such as honey, plasticizers (glycerin and/or dextrin), and preservatives to protect from spoilage or to improve the flow characteristics.
Could you please comment on what ingredients go into your gouache?
Sincerely, James Gurney
 |
| Top: transparency test, bottom: value shift test |
None of the companies paid me anything or asked for any kind of special favor. But they all gave me thoughtful answers. Here's what I heard back:
Holbein
"You are correct, there is so much differing information on Gouache from manufacturer to manufacturer. Here is what my understanding is with respect to competitive Gouache lines and what Holbein has always offered on theirs.
"- Almost every gouache line, regardless of origin, contains typically either talc, marble dust, Calcium Carbonate or titanium dioxide. It is very easy to tell when using a gouache that contains these ingredients. The colors tend to be drab and every color will have a chalky/milky overtone.
"- Holbein does not add any of these ingredients. Typically they achieve opacity through pigmentation. Holbein gouache is therefore slightly less opaque than other gouache lines, but offers superior color saturation, handling qualities and all colors lack that chalky/milky look. Holbein uses a moisturizer, Polyethlene Glycol and a preservative, benzisothiazoline.
"- Holbein acryla gouache uses a pure acryl resin as its base.
I hope this helps and please let me know if you have other questions."
All the best,
Timothy S. Hopper
Executive Vice President
Holbein North America
Winsor Newton
"Great question! In fact, gouache can be rendered opaque through two different formulation approaches. The first, and most commonly used, is through the addition of opacifiers like calcium carbonate or titanium dioxide or other things. The result is greater opacity, but the clarity and intensity of the color is compromised, sometimes quite appreciably.
"The other approach is to use pigments that tend to be naturally opaque and to load the formulation so heavily with pigment that opacity is the result. Of the two approaches, the second is the one we use. The opacity really and truly comes just from the pigment load.
"I would also like to tell you how much I enjoy your book, 'Color & Light'. I teach and recommend it to all of my students. It is the best book on the subject I have seen. It is a great book! I wrote a book for North Light about twelve years ago. 'Colour Secrets for Glowing Oil Paintings' so I can appreciate the amount to time and work it takes."
Best wishes.
Doug Purdon
Technical Advisor
P.S. I just received this reply from our technical manager.
Some opacifier is added, but the formulations rely predominantly on being heavily pigmented.
I suspect that when the pigments are very transparent such as Pthalo Green or Blue this would be necessary to ensure that they had sufficient covering power.
Utrecht
"Historically, Utrecht paints have been formulated with heavy emphasis on single-pigment colors to deliver the unique characteristics of the high quality raw ingredients we use, and this is still true of our Designer's Gouache line. Consistent with this goal, we use opacifiers and matting agents only where needed, in the minimum effective proportion. Depending on the individual color, we may use inert pigments like blanc fixe or barium sulfate to achieve an opaque, matte appearance.
"A few including Cadmium Lemon Yellow, Cobalt Blue Hue and Naples Yellow have a small amount of titanium white added, either to achieve a hue consistent with a traditional color or to bring a pigment to its best advantage. More information about pigment content is included on the product MSDS:
http://images.utrechtart.com/Content/MSDS/UT-Designers-Gouache-13.pdf
"Our objective was to offer designer's gouache worthy of the fine artist's palette, something that would never be called "chalky". There may be more variation in opacity/transparency across our assortment than with some brands, but that's a deliberate choice we think makes Utrecht Gouache such an excellent paint. Since skillful and sensitive use of white is so important in gouache painting, we feel that producing tints is best done on the palette by the artist. After all, you can always add white, but you can't subtract it.
"The binder for Utrecht Designer's Gouache is pure gum arabic. We do add antimicrobials, wetting agents and plasticizers. Our approach is to develop each color individually rather than a generic palette, so there is no overall single formula for any of our professional paint assortments. I will have to consult our Brand Manager to find out which colors include specific agents. None of the colors in our gouache line include ox gall. I'll review my archives and see what other information I can discover. Thanks for your interest in Utrecht paints!"
Matthew Kinsey
Utrecht Art Supplies
M Graham
"Thanks for asking. As a small child I wanted to be either a ballerina or an archaeologist so I have been fascinated with Dinotopia for years. Never occurred to me that I would be a paint maker.
"When we looked at entering the gouache market, many products were termed "designers" gouache. The idea was to make a design, take a photo and throw the original art work away. Many of the colors were fluorescent or not lightfast because the work was "swimsuit fashion" and permanency did not matter.
"We decided to go with a "fine art" version instead. We use the same pigments as our oil, acrylic and watercolors so there are some that are so transparent that opacity requires whiteners. Instead of formulating with opacifiers or whiteners, we leave this decision to the artist. Or the color can be diluted all the way to a wash without chalkiness.
"Since our whole operation is 9 folks and a part time stray cat in a 3000 sq. foot cinderblock building surround by hops fields in rural Oregon, we do not go much farther in discussing our formulations."
Diana Graham
Caran d’Ache
"Acrylic, watercolor and gouache are waterbased paints. Acrylic is resin based and watercolor and gouache are gum based (resin is not watersoluble, reason why you can’t solve acrylic after it has been dried) and gums are watersoluble.
"Watercolor is transparent, reason why there is no filler in the composition. It is just a big amount of pigment ground in an excellent gum like arabic, or better, traganth gum.
"Gouache and Acrylic are opaque by definition, reason why they contain calcium carbonate to give them opacity. The binder used for gouache is often potatoe starch (dextrin) but it can be also arabic gum in case of extra fine gouache.
"Sometimes, pigments are opaque enough not to be mixed with calcium carbonate (chalk). It is more in the case of mineral pigments like iron oxides or earth (like sienna, umbers etc..).
"Hope you will find answers to your questions."
Regards
Eric Vitus
Fine Arts Manager
CARAN D'ACHE SA
Richeson
"We have never manufactured gouache, so I am very short on knowledge. In general, most gouache today, particularly at lower quality levels (tempera paint) will contain chalk, because it makes for great opacity and is a cheap filler."
"For more expensive lines of gouache, it seems to me that it’s not likely/possible that something is not being added. For example, Ultramarine blue is a transparent blue, but shows up in a gouache line as opaque. This suggests that something has been added. There are opacifying pigments (don’t quote me on the correct terminology), really just additives meant to provide certain properties to paints that can be added. I suspect that while they are not adding Chalk, they are likely adding these opacifying “pigments”. Now for you and me, a pigment should be definable as a color of some sort. The opacifying pigments I know would not make any sort of recognizable paint."
I hope this helps.
Darren Richeson
President
Jack Richeson and Co., Inc
.
makes a 48-tube set of "hybrid" gouache/watercolor paints. They're pigment-rich, non-toxic, and use gum arabic as the binder and most of the colors can be used transparently or opaquely. But note that 8 of the 48 colors are not lightfast pigments, so they're better for designers or sketchers than gallery artists. The set is priced around $180, not bad considering they're 20ml tubes, while most other brands are 15ml.
(I got a set of these in Australia and used them to paint the comp for the dino stamps)
he talks about diagonals.
—but that's another book for another book club.
