Post 335 – by Gautam Shah
Gouache is painting-technique using is water-soluble but opaque colours. It is different from art of water colours that are transparent. Gouache uses opaque colours that cover the white of the paper surface and as a result shows up as a denser colour effect.
Gouache is a French-word, often spelled as guache pronounced –gwash, adopted from the Italian guazzo or aguazzo, for ‘mud.’ Guazzo, a term originally applied to the early 16th C practice of applying oil paint over a tempera base. The term is now broadly used to describe any drawing made in body colour. A Body colour is any high viscosity water-soluble colour which also contains white pigments and extenders. (A white pigment has high refractive index whereas an extender like chalk has low refractive index or low covering capacity. An extender though adds the mass, and increases viscosity). As a white pigment, artists in 15th C used Lead white. Later during 19th C zinc oxide replaced the lead white.
Water colours need to be worked by laying darker colors on top of light. But in gouache the background, even if of darker colour can be painted first, and light colours, just as in oil painting, can be layered on top of it and that is less restrictive way to work.
Gouache colours use larger proportion of water soluble gum as the binder, than the art-water-colours. The binder was originally gum arabic, but now increasingly vinyl and acrylic emulsions are used. Gouache colours are used to create highlights in water colours. Aquapasto is a viscous thickening medium made of gum arabic and silica (now synthetic emulsions and gels), which is used to give an impasto effect (lit. =to knead dough) to add texture to water colour and gouache paintings.
For gouache, the pigments are bound with glue and mixed with white pigment and extenders. Gauche, due to the opaque colourants, lacks the delicate luminosity of true water colour. Its colour massing is substantial, and with impasto effect can have a texture closer to oil-painting work. Gauche colours are water colours so dry to a lighter shade compared to oil Paints that dry to a darker shade. Gouache has widely used in the middle Ages for illuminated manuscripts. It became particularly popular in the 18th C. French painter François Boucher used it. In the 20th C. artists used gouache with impasto effect to create modern expressionistic effects. Modern Gouache is opaque water colour, popularly known as the poster colour. It is used for commercial art work such as posters, illustrations, comics, and 20th C animations.