Acrylic Primer
Acrylic primer acts as a size, sealing the fibres of your substrate, while also giving a slightly absorbent, textured ground suitable for oil or acrylic painting. Primers can be transparent, white or tinted, and are best applied in several thin layers.
The difference between acrylic gesso and acrylic primer is that acrylic primers contain less chalk. They therefore produce a smoother, less absorbent surface, which some painters prefer.