Watercolor painting to paints that use water-soluble, complex carbohydrates as a binder. Originally (in the 16th to 18th centuries), watercolor binders were sugars and/or hide glues, but since the 19th century, the preferred binder is natural gum arabic, with glycerin and/or honey as additives to improve plasticity and solubility of the binder, and with other chemicals added to improve product shelf life. The term "bodycolor" refers to paint that is opaque rather than transparent. It usually refers to opaque watercolor, known as gouache. Modern acrylic paints use a acrylic resin dispersion as a binder. Watercolor painters before the turn of the 18th
Gum over platinum Gum over platinum Gum over platinum is a historical chemical photographic process, which was commonly used in art photography. It is a very complex process, in which a specially treated platinum print photograph is coated with washes of gum arabic, then re-exposed to the same photographic negative. The finished process results in a sepia toned print, and is said to impart added luminosity and depth. It is sometimes called "pigment over platinum". To sensitize the gum arabic it must first be placed in contact with ammonium or potassium dichromate. Gum arabic is not photosensitive by itself. To clear the chromic