The following recipe is how to provide gesso. Gesso is made using gilders whiting (very refined and finely crushed chalk) and Rabbit Skin Glue. Gesso is used to provide a thick hard coating onto the surface to be water-gilded. It can also be used as a finish in its own right. Reheat an appropriate amount of Rabbit Skin Glue (10-1) in a double boiler, ensuring, of course that it does not reach boiling point. Once it has melted, lightly tap the bottom of the container to remove air bubbles. pour the mixture into a container in which you wish to make the gesso. I use a clear glass bowl.
Using a metal sieve, gently add Gilders Whiting to the rsg mixture. Do this slowly and wait for all the whiting to drop to the floor of the glue. Occasionally gently tap the bottom of the bowl to ensure even settlement of the whiting mix and to eliminate air bubbles. Keep going until it starts to peak through the surface of the RSG. Although the amount of whiting will vary, it should be approximately the same volume as the glue-size used. Leave this to settle for about ten minutes allowing the air bubbles to escape (gently tapping the bottom of the canister again at this time).
Once the whiting has completely settled and air bubbles are eliminated as much as possible, gently stir the mixture until an even mix is achieved. Be careful at this point not to introduce any air bubbles into the mixture! The mixture itself should feel really thick and creamy. If needed, the gesso may be strained through a pair of old tights to remove lumps at this point.
If possible, leave the mixture to set to help further eradicate any air bubbles still in the mixture, although it can be used from this point on. When applying successive layers of gesso to the surface, care should be taken that the gesso remains in a liquid state, as just like the rsg, it will set into a jelly. Between coats of gesso, add just a few drops of water to the mixture. This will help each layer to be slightly weaker and help prevent cracking. A small amount of water is also naturally lost due to evaporation.
Just like the rsg, gesso has a shelf life of about one week and will need to be stored in the fridge.