Gesso

Introduction

Gesso is a white paint mixture consisting of a binder mixed with chalk, gypsum, pigment, or any combination of these. It is used in artwork as a preparation for any number of substrates such as wood panels, canvas and sculpture as a base for paint and other materials that are applied over it. Gesso is also used in the creation of fine detailed and polished surfaces in the realm of sculpture and craftwork.

History

The use of gesso dates back to the Renaissance period, where it was used by artists to prepare their canvases and panels for painting. The term "gesso" is derived from the Italian word meaning "chalk", referring to one of its primary components. Gesso was traditionally applied in many thin layers, each layer sanded smooth before the next was added, to create a surface that was as smooth as possible for the application of gold leaf and other fine detail work.

Composition

Traditional gesso is a mix of an animal glue binder (usually rabbit-skin glue), chalk, and white pigment. The binder is heated with water until it forms a gel, then the chalk and pigment are added. This mixture is applied warm and dries to a hard, slightly absorbent surface. Modern gesso is made of a binder of acrylic polymer medium, calcium carbonate (marble dust) and a small amount of titanium white pigment. This gives it a bright white color that is more opaque than traditional gesso, and it can be applied in thinner layers.

Uses

Gesso is used to prepare a surface for painting, providing a slightly textured and absorbent ground that allows paint to adhere well. It also protects the substrate from the damaging effects of paint, particularly oil paint. Gesso can be tinted with acrylic paint to provide a colored ground. It can also be textured to create a rougher surface for paint to adhere to, or sanded smooth for fine detail work. Gesso is also used in sculpture to prepare the surface of the raw material, such as wood or metal, before the application of paint or gold leaf.

Application

The application of gesso is a crucial step in the preparation of a canvas or panel for painting. The gesso is typically applied in thin layers, allowing each layer to dry before applying the next. The number of layers applied depends on the desired level of smoothness and absorbency. Once the final layer is dry, it can be sanded to create a smooth surface. The gesso can also be applied in a textured manner, using a brush or other tool to create a rough surface for the paint to adhere to.

Variations

There are several variations of gesso available, each with its own unique properties. Acrylic gesso is a popular choice for artists working with acrylic paint, as it provides a flexible and non-cracking surface. Oil gesso, also known as oil ground, is formulated for use with oil paint. It contains an oil binder instead of an acrylic one, providing a less absorbent surface that is ideal for oil paint. There are also colored gessoes available, which can provide a colored ground for your painting.