A primer is the undercoat, the preparatory coating put on the painting ground or the surface material before applying the paint. Priming ensures better adhesion of paint to the surface, increases paint durability, and provides additional protection for the material being painted. Priming creates a buffer between the canvas and the paint of a painting. Generally, priming is achieved by applying multiple layers of acrylic gesso, clear acrylic medium, animal glue and oil priming white.
There are 4 reasons why priming is essential. First, priming protects and seals the painting ground. Second, it makes the canvas less absorbent. Third, it provides a smoother surface with enough grit for the paint to bind onto, and most importantly, priming ensures that every hue applied on the canvas beautifully shimmers across the picture plane.