What Is Gesso?
Gesso is a mixture used as a primer base for applying paint. It is a combination of white paint mixed with chalk or gypsum with a binder. It is applied to various painting surfaces, especially wood or canvas. If no primer is used, the painting surfaces will absorb the paint excessively and unevenly. This ends up with dull, patchy and disappointingly uneven paintworks. Ready-prepared gesso is available in all good art supply stores.
Traditional Gesso
Originally gesso was made using rabbit-skin glue, chalk and white pigment. This mixture has been traditionally used for hundreds of years as a base for painting. Unfortunately, it tends to crack over time, especially in warm, dry temperatures or damp conditions. This causes loss of paint and flaking, ruining many old paintings.
Acrylic Gesso
Acrylic gesso is a relatively modern invention. Chalk, acrylic resin and white pigment are combined to produce a non-absorbent acrylic gesso. It is sold pre-mixed and ready to use for preparing painting surfaces. It is perfect for use with acrylic paints, they adhere readily.
It can also be coloured with acrylic paint to provide a tinted painting surface. Not everyone wants to paint on a brilliant white ground, having the opportunity to paint on a different coloured surface is an interesting exercise. Some artists even use black acrylic gesso.
However, it has been noted that acrylic gesso is incompatible with other paints, especially egg-tempera. Even oil paints may well flake off in time.
So now you know what gesso is, what it is made from and why it is used, go and gesso a piece of wood, sand it lightly. Then apply more coats of gesso, wait for it to dry and start acrylic painting!!
