There was a student in a college watercolor class who was in a discussion with his professor about various techniques and styles. The professor pointed to an example and commented on the use of gouache to achieve opaque layers. Upon seeing this, the student remarked “Oh, so that’s not actually watercolor.”
There still seems to be a notable lack of knowledge about gouache, even among art communities, and we thought we’d shed some light on this venerable painting medium.
The most commonly used definition of gouache is “opaque watercolor.” So… first we need examine what watercolor is, and to define it. In its most basic formulation, watercolor is pigment, bound with gum arabic. This formula ensures that the paint is water-soluble, and that even after drying, will continue to uphold this characteristic. (Interestingly, some of the earliest pre-made watercolor resembles ink sticks from China and Japan, at least in functionality.)
Gouache originally was not a separate type of paint, but rather a modification on transparent watercolor. As early as Persian manuscript illumination, artists would mix a strong, opaque white into their watercolors to ensure opacity. The word “gouache” comes from “guazzo,” an Italian term for the opaquing technique. In this style of execution, gouache is used as a term for a technique used in conjunction with watercolors. In this day and age you can still work in this method, but for ease and convenience, many painters buy pre-made gouache. Pre-formulated gouache can differ in composition by manufacturer and quality grade. Basic and student grades are generally made of pigment and gum arabic with the addition of whiteners (like chalk). Higher-end brands of gouache are often touted as formulated with high pigment loads and coarser pigment than watercolor, so as to yield the purest color possible without the need for additives. Some pigments inherently lend themselves towards a more transparent characteristic, and in those cases, additional opacifiers may be used. Nowadays, the term gouache is used to refer to a specific painting medium that has its roots in a painting technique.
There’s a rather funny story that tells of an argument between British painters in the 1800’s. Two sides feuded over what was acceptable “true” watercolor painting. One side maintained that watercolor in transparent application was the superior way to paint, and the opposing side contended that the use of “body color” (opaque watercolor or gouache) was preferable. The polarization between the two groups went on to skew the biases of painters for generations to come. Though this story is just something we’ve heard and its absolute credibility cannot be confirmed, it is a fun way to think of how some peculiar attitudes manifest themselves today. Many watercolor painters identify as “purists,” and will espouse that only transparent watercolor constitutes true watercolor painting. However, it is interesting to note that many of the great watercolor artists, Turner, Homer, and Sargent, to name a few, often incorporated opaquing techniques into their works.
Gouache is just another form of water-based media that handles like transparent watercolor. It’s a wonderful way to paint opaquely. It dries quickly but is always re-workable. It harmonizes well with other media. It is totally intermixable with watercolor, and when dry is suitable to be drawn over. It also photographs and scans beautifully, which has made it a favored paint of illustrators. It has a solid history as a versatile and efficient painting medium, and still enjoys contemporary popularity.
But… how the heck do you pronounce it?! Just say GWASH!
For an even more extensive look at gouache: http://www.handprint.com/HP/WCL/pigmt7.html
Another intriguing article on watercolors: http://www.metmuseum.org/toah/hd/bwtr/hd_bwtr.htm