Water-Based Pigments, Continued
Gouache
characteristics
Gouache
storage
Gouache
finishing
Casein
Casein
permanence
Casein
characteristics
Casein storage
Gouache is opaque and chalky in appearance. Gouache should be applied in
thin layers; otherwise, thick layers may become brittle and crack. Gouache
is ideal for large areas of solid color and for small detail. Gouache in light
colors dries darker than when wet. Gouache in dark colors lighten as it
dries.
You may store the gouache for short periods in an enclosed palette with a
moist sponge or paper towel inside if you finish painting and have pigment
left over. The moist sponge or paper towel will release moisture in the air
allowing longer storage periods.
Gouache has a matte surface and does not require any special finishing
techniques.
Casein is a water-based pigment made by combining a milk derived emulsion
with oils, a stabilizer, and pigment. The formula for creating casein varies
from manufacturer to manufacturer.
Therefore, it is wise to select one
brand of casein and use it exclusively.
Casein is a relatively permanent pigment that is not rated by degrees of
permanence. Casein is centuries old with only recent emulsion refinements.
Casein is not fluid like watercolor and gouache and not flexible like acrylics.
Casein is water soluble when wet but, water proof when thoroughly dry.
Casein is opaque with some amount of white added to each color. Casein is
brittle and will crack when applied in thick layers.
Casein does not store well. Cheaper brands of casein lacking sufficient
fungicides and stabilizers tend to mold and decompose. You should prepare
the amount of casein you expect to use in one sitting. Clean your brush often
during a painting session. Scrape excess paint from the palette and
thoroughly clean the palette before putting it away.
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