|My rocks for paint collection.|
I have a tangled answer. Unfortunately, it is a lengthy story.
To begin, the all-knowing Wikipedia reports the modern term "gouache" springs from "guazzo" a late period Italian word for mud. This referred to a late period practice of applying oil paint over a tempera base.
Not what I expected.
What is gouache then?
As a modern background basis, The Grove Encyclopedia of Materials and Techniques in Art tells us:
Gouache [Body Colour] ... also called body colour, is simply a water-based paint rendered opaque by the addition of white paint or pigment (i.e. Chinese white) or a substance such as chalk, or even marble dust. It is an evolved form of tempera paint, descended from distemper. The application of the term is often imprecise, but it is most often associated with colours bound in glue-size or gum... (p. 259)
That is a lot to take in, but there is more.
The history and evolution of gouache are vague, since its characteristics are common to several types and traditions of painting. Ancient Egyptian wall paintings and Indian miniatures, for example, answer to its general description. Although in Western Art it associated at first with tempera painting and manuscript illumination,... The tapestry cartoons of the Lives of SS Peter and Paul (1515-1516; British Royal Collection, on loan to the Victoria and Albert Museum, London) by Raphael (1483-1520) can quite reasonably be described as gouache paintings, as can the watercolours studies of the Young Hare (1502) and Large Piece of Turf (1503; both Vienna, Graphische Sammlung Albertina) by Albrecht Durer (1471-1528). From the 16th to the 18th century gouache is represented by the body colour of the limner or miniature painter and by the decorative use of distemper. ... (p.259)
Watercolour may be made opaque by the addition of a further agent. In this form it is called GOUACHE, or traditionally body colour. The extra 'body' is usually Chinese white, an opaque white originally based on lead, and later on oxide of zinc, which is added to all the colours. Barium sulphate or precipated chalk may also be added to the pigments as opaque extenders. To obtain the greater opacity and flexibility required of gouache and both pigment and glycerin are used in greater proportions than for transparent watercolours. ... Whereas in pure watercolour, tonal gradations [watercolor] must be anticipated, and a dark one reduced by thinning down or washing out with water, with gouache a pale colour may be laid over a dark. (p. 759)
I also found Steven Sheehan's notes on The Notebook describing Ralph Mayer's The Painter's Craft. An Introduction to Artist's Methods and Materials, telling us:
A gouache painting is a watercolor done in opaque instead of transparent coloring; whites and pale tints are obtained by mixing titanium or Chinese [zinc] white with the colors instead of by utilizing the white of the ground. ... Gouache pigments are ground with a greater proportion of vehicle to pigment, and when they are painted out, the result is a continuous paint film of appreciable thickness rather than the thin wash or stain produced by watercolor.I don't own a copy of Mayer's book, but The Notebook is a searchable, update-able website for "understanding visual art references and resources", active since 1993. I'll take their word for it.
Sheehan goes on to say:
Inert pigments, such as blanc fixe or chalk, are often ground in with some of the colored pigments, not as adulterants but in order to increase their bulk and to improve their brightness or opacity. Those colors which are ordinarily transparent in oil and watercolor act as body-colors in gouache, and often yield somewhat different color effects. [pp. 152-154]
So, what period sources describe adding chalk or blanc fixe to 'illumination' paints?
Theophilus' On Divers Arts, written about 1122 is the oldest existing manual written by the artisan himself. The techniques he wanted to pass on were translated and annotated by John G. Hawthorne and Cyril Stanley Smith.
Hawthrone and Smith write about the different words Theophilus used for various period whites. If he used "Ceruse" he meant the basic white lead carbonate pigment. If he used the word "white" without more clarification, it was probably whiting, calcium carbonate, ground bone ash or lime. While still white, they believe gypsum or chalk were then used as gesso, not as whiting. (p.15, 16)
The distinction is important when you read Theophilus actual text because he flips around as he describes pigment production. That distinction means when he makes the color he calls "Veneda" for the eyes he is using whiting not lead white. He writes:
mix black with a little white...Lay in the pupils of the eyes with it. Add still more white to it and lay in each side of the eyes. Paint plain white between the [areas covered by] this pigment...(p. 18)Similarly, he also describes making a face highlighting pigment.
If the face turns out to be dark so that one coat of highlighting pigment is not sufficient, add more white to it and draw fine lines with it all over the first highlights. (p. 18)He does this to make lighter colors to highlight clothing (p. 21) and to paint a rainbow. (pp. 23-25) Even though this is essentially a "gouache" its purpose is to make a tint.
The tangle now comes because these descriptions may be written about icons and frescoes, not manuscript illumination. ... Rats!
However, Theophilus' 'chapter' 32 fixes that. After describing tempering mediums and their use he states:
...Prepare all the mixtures of pigments for a book as above, if you need them for painting figures. In a book all pigments should be applied twice, first thinly, then more thickly; but only once for letters. (p. 38)I find this intriguing. It is apparently the first written glimpse of an artist making an opaque paint to highlight manuscript illumination figures.
Those are amusing historical references, but debatable reasons for adding white to pigments. Take heart, I have found supporting 'gouache' evidence.
There are recipes of a fillero being added during pigment production in the anonymously published 1596 English A Booke of Secrets.
One describes making paint from Brazil wood, a transparent color. After the color is produced one lengthy recipe finishes with "you may likewise put into it some chalke beaten to pouder". (Secrets p. B2)
That sounds to me as if the chalk is optional. If it is optional, does that mean the color isn't changed by adding chalk? If it doesn't change it significantly then I think we've found evidence.
The Booke of Secrets also provides two recipes for making Azure, one using white lead the other chalk.
Take one ounce of white lead, nine ounces of Indicum, pour good vinegar into it, put them in a leaded dish, let them seeth well, and that which swimmeth on the top is the colour.
Take two parts of chalk made of egshels, one part of Verdigreece, one part of Salarmoniacke, mingle them together with strong vinegar, put them in a new pot, stop it well, that no aire issue forth, set it in a warme place for a month long and it will be Azure.There is more to this story than I have written. It is well known lead white could not be used with verdigris and orpiment. What whiteners worked with them? How well did they work? What media were they used in? What colors were thick enough on their own to not need body added?
If you look into the whole Medieval whiteners' tangle you will find more questions than "Is gouache period?" The trick becomes finding the right question for the fascinating answer you have.
Related Prior Post:
Gouache And Watercolor Paint Comparison
Why Buy More Scribal Paint Colors?
The Getty, Art & Architecture Thesaurus--Gouache
Handprint--Gouache and Body Color
Paint Making--Inert, Fillers had a bandwidth limit
The Scientist's Scroll--blog
Studio Arts--Gouache Hints and Tips
Winsor and Newton--Gouache Articles