Gouache the formula of the paint is "acrylic gouache". Its highly concentrated pigment is similar to traditional gouache, but it is mixed with an acrylic-based binder, unlike traditional gouache, which is tempered with gum arabic. It is water-soluble when wet and dries to a matte, opaque and water-resistant surface when dry. Acrylic gouache differs from acrylic paint because it contains additives to ensure the matte finish and the reworking time is slightly extended. Some brands can sometimes be removed or "lifted" for several hours after application, during their drying time. Gouache Gouache (; ), body color, opaque watercolor, or gouache, is
Gum arabic insoluble in water upon exposure to ultraviolet light. In the final print, the acacia gum permanently binds the pigments onto the paper. Gum arabic is also used to protect and etch an image in lithographic processes, both from traditional stones and aluminum plates. In lithography, gum by itself may be used to etch very light tones, such as those made with a number five crayon. Phosphoric, nitric or tannic acid is added in varying concentrations to the acacia gum to etch the darker tones up to dark blacks. The etching process creates a gum adsorb layer within the matrix that