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How to Fix Gesso Frames

Gesso is a mixture of chalk and glue used to create a smooth cloth or wooden canvas. According to the Journal of the American Institute for Conservation, artisans have used gesso as a preparation layer since ancient Egyptian times. Typically, gesso was applied over ornate wooden frames to prepare them to accept lacquer or gilding. Unfortunately, gesso is extremely sensitive to changes in temperature and humidity, causing it to crack, crumble or otherwise separate from its original substrate. If you have an older gesso frame that has deteriorated, it is possible to remove and restore the damaged gesso.

Things You'll Need

Granulated rabbit skin glue
Water
Double boiler
Candy thermometer
Calcium carbonate
Large canning jar
Plastic container
100-grit sandpaper
1 to 10 pounds sawdust
Paintbrush
120-grit sandpaper

Instructions

Preparing Gesso
- 1
  Mix 1 1/2 teaspoons of granulated rabbit skin glue and 1 cup of water in the upper pot of a double boiler.
- 2
  Allow the glue to soak overnight.
- 3
  Fill the bottom pot of the double boiler with water.
- 4
  Assemble the double boiler and begin warming the glue.
- 5
  Place a candy thermometer in the glue mixture and warm it to 127 degrees Fahrenheit.
- 6
  Place 2 cups of calcium carbonate, also called whiting, into a large canning jar.
- 7
  Add the warm glue mixture to the jar and mix thoroughly.
- 8
  Place the jar in a bath of warm water once the jar is warm to the touch. This will keep the glue fluid enough to paint on the frame.
- 9
  Reheat the gesso before applying a new coat by placing the cold jar in the upper pot of the double boiler filled with cold water. Placing the cold jar into hot water will cause it to crack or explode.
Fixing Gesso
- 10
  Sand the frame with 100-grit sandpaper to remove any paint or protective coating.
- 11
  Cover the portion of the frame covered in gesso with damp sawdust and allow it rest overnight. Exposed wood may warp or swell from the water, so avoid applying it to the exposed frame where possible. For small picture frames, you may need only a 1-pound box of sawdust. However, full-length mirror frames may require as much as 10 pounds of sawdust or more.
- 12
  Peel the gesso from the frame. The water from the sawdust will have made the gesso rubbery, allowing it to separate easily from the frame.
- 13
  Wipe the frame to remove any debris.
- 14
  Apply a thin, even coat of warm gesso to the entire frame with a paintbrush. If the frame is ornate, you will need to work with a fine brush to work the gesso into the details.
- 15
  Allow the gesso to dry to the touch before applying a new coat. In a well-ventilated area, this could take 10 to 30 minutes.
- 16
  Apply between three and five thin coats to build a sufficient base without obscuring any of the details.
- 17
  Sand the gesso lightly with 120-grit sandpaper to rough the gesso and create a base for the paint, lacquer or gold leaf.
- 18
  Decorate as desired.

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