M. Graham & Co. - Artists Gouache - 15 ml - Pthalo Blue (Primary) - Crafted with the same lightfast pigments found in all M. Graham colors and pure blackberry honey, this fine art gouache was created for the artist seeking both permanence and ease of use. Free from chalk and opacifying adulterants (leaving that choice to the artist), each M Graham Gouache color is entirely dependent upon the nature of the pigment for its color and opacity. A reflective matte finish provides a vehicle to be used alone or in mixed media combination with watercolor to create permanent works of art.There is no principal difference between gouache and watercolor pigments, but the former need not be ground as finely and requires no wetting agents when made into paints. The lean gouache color will only crack or peel when too many thick layers are superimposed or when it is applied as impasto. The color should be layered in thin applications. M Graham Gouache colors are designed to be applied opaquely, however the nature of each pigment will create variations of opacity.