Gesso
Gesso (Italian pronunciation: [ˈdʒɛsso]; "chalk", from the Latin: gypsum, from Greek: γύψος) is a white paint mixture consisting of a binder mixed with chalk, gypsum, pigment, or any combination of these. It is used in artwork as a preparation for any number of substrates such as wood panels, canvas and sculpture as a base for paint and other materials that are applied over it.
"Gesso", also known "glue gesso" or "Italian gesso" is a traditional mix of an animal glue binder (usually rabbit-skin glue), chalk, and white pigment, used to coat rigid surfaces such as wooden painting panels as an absorbent primer coat substrate for painting. The colour of gesso was usually white or off-white. Its absorbency makes it work with all painting media, including water-based media, different types of tempera, and oil paint. It is also used as a base on three-dimensional surfaces for the application of paint or gold leaf. Mixing and applying it is an art form in itself since it is usually applied in 10 or more extremely thin layers. It is a permanent and brilliant white substrate used on wood, masonite and other surfaces. The standard hide glue mixture is rather brittle and susceptible to cracking, thus making it suitable for rigid surfaces only. For priming flexible canvas, an emulsion of gesso and linseed oil, also called "half-chalk ground", is used. In geology, the Italian "gesso" corresponds to the English "gypsum", as it is a calcium sulfate mineral (CaSO4·2H2O).
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