A water-soluble gum obtained from several species of the acacia tree, especially Acacia senegal and A. arabica , and used in the manufacture of adhesives and ink, and as a binding medium for marbling colors. Historically, gum arabic was used to increase the viscosity of ink, or to make it flow well, to prevent it from feathering, and to suspend the coloring matter.
It was particularly important in the days of the reed or quill pen. Solutions of gum arabic have long been used as adhesives for paper, but they are little used today. Gum arabic adhesives produce clear, easy brushing solutions which have no marked initial set but which will pass through a tacky stage on drying. The properties for which they are valued include ready solution in water following drying, readiness for immediate use, cleanliness and ease of application. Gum arabic adhesives, however, are generally too moisture sensitive for use in archival work. Also called "acacia gum." Extra special USP grade. Powdered.