Gesso is used by artists to prime a surface for painting.
Gesso is a primer used to create a smooth surface on art canvas. It provides a surface for the paint to adhere to while protecting the fabric of the canvas. A raw canvas is not suitable for either oil or acrylic painting since the fibers will absorb pigment, and heavy layers of paint will eventually crack and fall off the canvas. Gesso can be applied in thick layers to create a textured canvas, or thinned with water for a smooth painting surface.
Types of Gesso
Gesso is available commercially in professional and student quality. Student quality gesso has more filler product, such as chalk, and contains less pigment. Student gesso is opaque due to high filler content. Professional grade gesso contains less filler and more pigment which results in a thinner product. Student gesso can be thinned with water for easier application.
Coloring and Tinting
Gesso is usually white, but colored, black and clear gessos are available in a professional grade product. White gesso can be tinted using any water-based color, such as water colors, food dyes and acrylic paint. Pour some gesso into a small plastic container and experiment with tinting gesso by adding small amounts of acrylic paint or food dye until the desired color is achieved.
Homemade Gesso
Gesso can be made at home using equal parts of whiting chalk, white pigment and a glue solution. Rabbit skin glue is normally used, but other binding materials, such as casein paint, are also used. Prepare a solution of rabbit skin glue granules by melting them in warm water for one-half hour and then warm to about 140 degrees Fahrenheit. Do not boil the glue. Add the whiting chalk and a white pigment to the solution and mix thoroughly. Keep the solution warm during the application process. Apply six or seven thin coats to a stretched canvas. Allow the gesso to dry completely between coats.
Application
Apply gesso to a stretched canvas using a flat brush. Use a large brush for maximum coverage per brush stroke. Apply two or three thin coats and wait until the canvas is completely dry between applications. A raw canvas may require more than three coats of gesso to properly prime the canvas for painting because the fibers of the cloth will absorb the gesso primer. Brush strokes in the gesso can be removed by brushing the surface of with a dry brush or lightly sanding the surface.
