(which you can view here:
http://ukartsupplies.blogspot.com/2010/05/kent-artists-dawlton-barn.html)
... here is a reliable gesso recipe, for those of you who are interested in having a go... !
What is Gesso? - - Gesso is a chalk-based, highly absorbent painting surface, traditionally used as a ground for egg tempera painting. It tends to be found on old paintings made in Italy and Northern Europe, but is still used today in contemporary painting and remains a popular surface for egg tempera as well as other media.
There are many variatons of the basic gesso recipe, but it always consists of a combination of animal skin glue and a type of chalk. The most popular (and easiest to source from good art shops like ours!) are Rabbit Skin glue and whiting chalk (calcium carbonate).
Rabbit Skin Glue - - Can be bought either as a dry grainy powder, or ready-hydrated in a thick, jelly-like substance. If it is in powder form, place the required amount of powder into a clean glass vessel. Add cold water slowly (standard ratio is 1 part glue to 15 parts water). Stir, so that all the glue is covered and wet. Leave this mixture to stand for at least 30 minutes, stirring once or twice (if the glue is left unstirred it tends to clump together). After 30 minutes the glue will have swollen to form a mushy paste.
Tip for artists making their own stetchers - - Rabbit skin glue can be used as a size all on it's own. It is great for canvas if you want to prime the surface but retain the unprimed colour of the cloth. It also stretches the canvas nice and tight over the stretcher.
To turn the Rabbit skin glue into a usable solution, it must be gently heated through. The best way to do this is to sit the vessel in a bowl of boiling water. (And keep replacing with new hot water to keep the temperature up!) However, if the glue is over-heated, it will loose some of its water content and consequently will become stronger and stronger. (this could cause problems if there is a discrepancy of glue strength between different layers on the same panel, and could lead to warping).
Making Gesso - - chalk (or gypsum) 1 part : 1 part liquid (animal skin) glue
Always add the chalk to the glue, not the other way round. Spoon the chalk into the liquid glue slowly and allow it to fall beneath the surface, gradually absorbing into the glue by its own gravity. Try to avoid stirring as this will cause unwanted air bubbles. Once you have added the chalk to the glue, leave it for 15-20 minutes and allow it to settle on the bottom of the vessel. Don't worry if the glue cools and forms a jelly during this process - it can always be re-heated again in a water-bath. When ready to use, stir very slowly (again, try to avoid air bubbles). The gesso should have the consistency of single cream - if it is too thick simply dilute with some luke-warm water and stir slowly before using.
Preparing the surface - - A first 'grip' coat is generally applied to the panel surface, (this coat should consist mainly of glue) followed by 4 to 10 coats of gesso. Allow each coat to dry before applying the next. To avoid slight brush marks you can use a fine sandpaper to sand down each layer, ensuring an ultra-smooth finish.
As well as a perfect surface for egg tempera, gesso can also be used to try out more experimental techniques with other materials, and can be sanded down to remove or distort the image. It is a beautiful, traditional technique that has stood the test of time and I am sure it will continue to be a preferred surface for artists to paint on for many years to come.
(Information taken from 'The Artist's Handbook' by Pip Seymour ISBN 0-572-02866-0)
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