Gesso and Priming Materials are traditionally supposed to have some tooth or texture in order to provide better adherence for the paint. This is particularly important when using oil paints on an acrylic base. However, there are gessos that are designed to be sanded smooth. At the same time, a gesso is supposed to prevent all of the medium, traditionally linseed oil, from being absorbed into the underlying support. But if there were no absorption or tooth at all, the two layers would not form a polymer bond. The right gesso is a particular tradeoff, in which the properties of both the paint and the surface matter.
Before the 1950s, all gesso was made of animal glue. Since the 1950s, acrylic gesso has largely replaced animal glues. Most artists feel that acrylic provides a more flexible surface and creates a painting that is easier to maintain. However, Blick continues to make traditional materials available for those who want them.