crylic Gesso is the foundation of a painting very similar to white acrylic paint, it dries hard which makes the surface more stiff. Gesso prepares or primes the surface for painting. It is a paint like substance that is brushed on a canvas or substrate which prepares it for painting. Modern acrylic gesso is a combination of Acrylic polymer medium (binder), Calcium carbonate (chalk), A pigment (usually Titanium white) and Chemicals that ensure flexibility and long archival life. Gesso is the same as a primer, as in pre-primed canvas