Gesso Grounds from Ancient Recipes

Learning from artists manuscripts, a contemporary artist adapts a 15th century recipe for preparing grounds for oil painting on wood panels.

In her book, The Art of Arts, Anita Albus discusses materials and practices of oil and tempera painting that have either been lost or fallen into disuse. Albus makes a poignant observation that ever since the industrial revolution, it has been industry that dictates what materials are available to artists. Gesso production falls into this category alongside the preparation of paints and mediums. Artists have succumbed to the materials handed to us. She reminds us that prior to industrialization and typical of the European artists guilds of the 15th and 16th century; it was largely the artists themselves that prepared their own formulas and concoctions in painting.[1]

I began making gesso 20 years ago because it gave me a sense of control over the appearance of oil paint. After graduate school I was very frustrated by my lack of understanding of artists materials. I began researching different oil painting techniques such as multiple layering-glazing. My peers used direct or alla prima painting exclusively. Glazing in oil medium requires a ground that is more substantial than the common acrylic ground.

Adaptation of Cennino Cennini's Recipe

What I am about to describe is an adaptation of the gesso formula described by Cennino Cennini in his Il Libro dell Arte.[2] This formula is for a rigid support such as a wood panel. To use it on canvas decrease the strength of the size formula: 100 grams glue to 1 liter water for panels and 70 grams glue to 1 liter water for canvas. The following materials are required:

1. Gypsum. Hydrated calcium sulfate. Also called light spar. It is raw, unroasted plaster.
2. Zinc white pigment
3. Clean tap water or distilled water
4. Cheesecloth
5. Weighing scale
6. Glass measuring cup
7. Newspapers or drop cloth
8. Wooden spoon or medium large bristle glue brush
9. Rabbit skin glue (I prefer the kind in sheets, however the granular form will work well as long as it is of good quality)
10. Electric hotplate with temperature control
11. Double boiler

Sizing the Panel

The panel should already be sized with a 1:10 solution of rabbit skin glue and water heated in a double boiler. Let the glue sit in cold water and soak over night or for an hour or two. Never boil rabbit skin glue. It should be applied hot to all sides of the panel and thoroughly dried for 2–3 days. A second size is recommended.

Preparing the Gesso Ground

Begin making the gesso by heating up 8 ounces of the size solution in the double boiler. Never overheat it. When the size is just hot, remove the upper pan from the lower one on the hot plate. Turn the hotplate temperature to low. Mix 1 part zinc white pigment with 2 parts gypsum. Add 12 ounces of the gypsum mixture to the size very slowly, sprinkling it in little by little, being careful not to form lumps. Eventually use a tablespoon to scatter the remainder of the gypsum into the solution by sprinkling it around the perimeter of the bowl to avoid a build-up in the center.[3]

Using either a large stiff glue brush or a wooden spoon (I prefer the spoon), stir the mixture very carefully, avoiding rapid movements. The point is to stir, not mix completely. The gesso mixes on its own in the next step.

Pour the gesso into clean bowl. Clean the double boiler and brush or spoon. Stretch two layers of cheesecloth over the clean double boiler and pour the gesso through it slowly and carefully. Use your brush to get all the gesso out of the bowl and through the sieve.

Remove the cheesecloth. Wash your spoon or brush and carefully stir the gesso again. At this point the gesso may have cooled and congealed. Place it over the boiler making sure the water is very hot, and stir continually until it liquefies, then remove it immediately. Excessive heat will create air bubbles in the gesso, which will ruin the gessoed surface.

Applying Gesso to the Panel

The first layer is applied by stippling the brush loaded with warm gesso onto the board, being careful not to apply an excessive amount while using a tapping and pushing the brush on the surface. Alternate applications of gesso with a brush coat followed by a tap coat. The surface should begin to dry but still be moist between layers. Thorough drying requires a few days of dry weather. Avoid direct heat from sunlight or other sources. Alternate the directions of your brush strokes in each layer, building up the gesso coat to 6–8 layers.

To achieve a smooth luminous surface scrape the panel using a steel scraper with a straight edge 2 or 3 inches wide. The corners should be rounded off on a grindstone. However, it should have a slight burr on the edge. Hold the scraper vertical with both hands and place your thumbs firmly on the side facing you. With the burred edge facing you, pull it towards you. With the proper burred edge you should get a scraped rectangle. To achieve the proper burr use an Arkansas oilstone. Work carefully. Do not linger in one spot. Move in a criss-cross pattern until the panel is complete.[4]

Tempering the Panel to Control Absorbency

Wipe the scraped panel free of dust with a damp cloth. After the panel has dried several days or at least over night, it needs to be tempered. Tempering a panel means to make it less absorbent. I have found through much trial and error that one thin coat of fossil resin varnish (copal or amber) is sufficient. Bleached shellac may also be used. Use a 2- or 3-inch wide brush and load it completely with shellac. Without this thin layer, paint soaks into the ground thus compromising the integrity and otherwise permanent luminosity of the ground.

Troubleshooting

Let the panel dry for several days. Now is a good time to check for defects in the panel:

Unfortunately, there is no remedy for the first three defects. Streaks can be smoothed out and the pigment defect can also be smoothed down and lived with.

I strongly suggest reading the first chapter of Max Doerner's The Materials of the Artist and Their Use in Painting. Doerner gives a good general overview of grounds and glues. Practical information can also be found in The Practice of Tempera Painting by Daniel V. Thompson, Jr. Other references that I list below should be consulted and carefully poured over. It is important to discriminate from those that write about the "idea" of artists materials and those whose writings use primary and secondary historical references that are less theoretical and likely based on artistic practice.

Finally, I warn you about taking any of these formulas literally. Much can be lost in translations. Much more has been lost by misinformation. I have found valuable information in Doerner and Ralph Mayer. I have also found uncorroborated observations in both of their books. (I refer here to their discussion of natural fossil resins and use as a painting media.)

One must treat the making of gesso as a delicate process, not to be rushed through, but approached methodically and with contemplation. The same holds true when consulting historical treatises and other writings about technical art history.