Gesso

F. Ronca, Protein Determination in Polychromed Stone Sculptures, Stuccoes and Gesso Grounds, Studies in Conservation, 39, 107 120 (1994). 

An Impressionist artist, Henri Toulouse-Lautrec (1864-1901), painted pictures of dance hall patrons and dancers directly on brown paper supports. Other artists painted on canvas coated with gesso, a chalky substance mixed with glue and water. This is a popular ground still used by artists today. 

More often, modern artists use canvas supports for their paintings and coat their canvases with gesso. In 1979, Andrew Wyeth used such a canvas to paint Braids, a portrait of a woman. Interestingly, he used egg tempera paints similar to those used hundreds of years ago. 

How is a gesso painting different from a fresco painting ... 

In a gesso painting, a board support is layered with a plasterlike ground, the gesso, and a painting is made on this ground. 

Either of these gesso grounds will provide a brilliant white painting surface. Unlike a fresco painting, in a gesso painting the artwork is painted on a dry surface and does not soak into the surface. 

Gesso is also used when preparing a canvas for oil or acrylic painting. Canvas stretched on a frame is the support. The gesso ground is applied with a brush to the support, a procedure called priming. The gesso acts to seal the canvas fabric so that the paint applied will not soak into the canvas. 

In Activity 3.1, the students will prepare whiting compounds, substances that impart a brilliant white to a ground, which will be combined with other chemicals to produce a gesso paste. In Activity 3.2, the gesso paste will be applied to masonite board to prepare a... 

Compare the whiting compounds, CaC03 and Ca(OH)2, for brightness, texture, and consistency. Which compound would be a better whitener for a gesso ground Why ... 

The Preparation of Grounds Using Whiting Compounds to Prepare Gesso Solutions... 

Students will compare and contrast the properties of various types of gesso grounds. 

Students will debate the pros and cons of using a gesso ground for a painting. Materials... 

Apply the gesso to a masonite board (see item C). Cover the beaker with a watch glass. Store the gesso in a refrigerator between applications (it will gel between applications and should be warmed on a hot plate until it is just melted before using). 

B. Have students prepare a casein-based gesso ... 

C. Have students create a gesso ground by applying the gesso to a masonite board ... 

Using a 1-in.-width paintbrush, apply a thin layer of gesso to the scored side of the board. 

Continue applying layers of gesso (alternating the direction of brush strokes) until the gesso surface is about 3 ml thick. 

When the final layer is dry, sand the gesso surface using fine-grit sandpaper. 

Compare the gesso grounds prepared with regard to color and texture. 

In a class discussion, have students decide which gesso ground is the best ground for a two-dimensional work of art. 

For each chemical used in this activity, explain its role in creating the gesso product. 

In Activity 3.3 you will experiment with nonobjective art using the gesso grounds prepared in Activity 3.2 and egg tempera paint prepared in Activity 2.5. Egg tempera was used by many artists in Europe during the fourteenth and fifteenth centuries. Today, it is still used by some artists, notably Andrew Wyeth. In this technique, egg yolk is mixed with distilled water to form a binder, and a pigment is added to make egg tempera paint, which is applied to a gesso ground. 

Students will apply paint to a prepared gesso ground. 

Egg yolks, pigments (see below), powdered or liquid tempera (poster paint) in assorted colors, and distilled water, or egg tempera paint prepared in Activities 2.3-2.5 gesso grounds prepared in Activity 3.2 narrow-width paintbrushes with soft bristles paper towels mixing trays water containers pencils. 

Paint on the gesso ground to create a feeling of movement—across, up, down, around, in, out, or any combination of these—using shapes and lines. 

Try to vary the size and type of shapes and lines, vary the colors, and use the entire gesso surface. 

A whiting compound is an insoluble, very white substance that provides a smooth, solid coating needed in a gesso ground. 

The rabbit-skin glue or the cottage cheese provide adhesives to bind the whiting compounds into a thick, creamy solution that can be applied to a masonite board and built up layer by layer to form a solid ground. Calcium sulfate and calcium hydroxide dehydrate as the gesso dries and solidify to form a cement ground. They also provide a white solution that is made more brilliant with the addition of titanium dioxide. 

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