Gesso Information & Instructions

 

USAGE OVERVIEW:

Gesso is used as a base-coat on objects that will be water gilded. It fills imperfections in the surface of the object, and provides a smooth adhesive base for the clay bole and gold leaf.

 

PREPARING GESSO:
Gesso is made by combining prepared rabbit skin glue (RSG) and whiting, which is very finely ground calcium carbonate (chalk).The ratio is approximately 1 part by volume of RSG to one part of whiting. The final thickness of the gesso will depend on personal preference, and can be adjusted. The RSG should be warm before being mixed, but it should never be heated to a boil. Whiting should be slowly added to the warm RSG, preferable through a mesh strainer to break up any lumps. Shake or tap the container to remove any air bubbles, and slowly stir until the final gesso mixture is creamy and has the approximate consistency of paint. The gesso can be thickened by adding more whiting, or thinned by adding more RSG or a small amount of warm water. The gesso mixture should be kept warm during the mixing process.

 

APPLICATION OF GESSO:

During use, the gesso should be kept warm but not hot. Normally between 6 to 10 coats are applied with a soft but sturdy brush, such as an ox hair brush. After each coat is applied and dried, it can be sanded with 400 or 600 wet/dry sandpaper to make it smooth. A dust mask is highly recommended while sanding the gesso. Each coat should be completely dry before the next coat is applied. Dry time per coat will be approximately one hour, depending on the temperature, humidity, and the thickness of the application.

 

Gesso will slowly gel and solidify as it cools. It can be gently warmed for continued use. If using gesso that has been previously stored and refrigerated, it should be warmed first, and slowly stirred to avoid air bubbles.

 

STORAGE:

Gesso has a short shelf-life and should be refrigerated in a sealed container. The refrigerated shelf life of prepared gesso is approximately two weeks, and it will develop an unpleasant odor when it stars to deteriorate. Dry powered whiting does not spoil, but may clump if exposed to moist or humid conditions.

SAFETY:

Gesso whiting is non-toxic, but it is made from very fine calcium carbonate (chalk) particles which should not be inhaled. If mixing gesso indoors or away from moving air, please use breathing protection that will keep any fine airborne particles from being inhaled and causing respiratory damage. Breathing protection should also be used when sanding prepared gesso.

 

DISCLAIMER:
The conditions, methods of handling and use of this product are beyond our control and may be beyond our knowledge.  For this reason, we do not assume responsibility and expressly disclaim liability for loss, damage or expenses arising out of or in any way connected to the handling, storage, use or disposal of this product.