potential longevity of a painting.

“Easel” paintings are supported by wooden or fiberboard panel or a fabric (linen/cotton) stretched on an expandable wooden frame (stretcher) or fixed frame (strainer). The canvas is then covered with a thin layer of animal glue or acrylic emulsion as a sizing layer. The coating (size) prevents the fabric from absorbing too much liquid and prepares it for the layer of gesso.

The ground layer is typically a smooth, white gesso film consisting of multiple layers of a mixture of water-based glue and ground chalk. The artist will often complete an under drawing in ink, charcoal, or pencil on the ground layer and then proceed to apply layers of paint.

Paint is made of colorants like ground mineral pigments, mixed with a sticky binding medium such as resin, oil, or egg yolk. Sometimes, a final layer of varnish is applied to protect the surface from moisture, scratches, and grime.