Watercolor painting Watercolor paint consists of four principal ingredients: a pigment; gum arabic as a binder to hold the pigment in suspension; additives like glycerin, ox gall, honey, and preservatives to alter the viscosity, hiding, durability or color of the pigment and vehicle mixture; and evaporating water, as a solvent used to thin or dilute the paint for application. The more general term "watermedia" refers to any painting medium that uses water as a solvent and that can be applied with a brush, pen, or sprayer. This includes most inks, watercolors, temperas, caseins, gouaches, and modern acrylic paints. The term "watercolor" refers
Gum printing copies. Gum printing Gum printing is a way of making photographic reproductions without the use of silver halides. The process uses salts of dichromate in common with a number of other related processes such as sun printing. When mixtures of mucilaginous, protein-containing materials together with soluble salts of dichromate are exposed to ultraviolet light, the protein content becomes tanned and resistant to solution in water. The untanned material can be washed away in warm water leaving a hardened, tanned protein negative. For gum printing a solution of gum arabic is mixed with either potassium or ammonium dichromate. The higher the