Term: Primer

A primer is a foundation layer that improves paint adhesion onto the support. The traditional oil paint primer was a quick drying, "lean" paint that sealed and prepared the surface to accept the subsequent layers of paint. Some of these primers were made of hide glue and solids (chalks); others were made of lead white pigment in linseed oil. In the modern sense, a primer refers to a coating that similarly prepares the surface for the acceptance of paint. Currently, there are a wide variety of water, alkyd, oil and urethane-based primers especially designed for the wider range of paintable surfaces.

From Golden Artist Colors