Rabbit skin glue granules
Double boiler (or similar)
Soak the granules in cold water for at least 2 hours.
A guideline for proportions would be:
Canvas sizing 1 : 30 (granules : water)
Chalk ground 1 : 15
Half chalk ground
Heat the soaked solution in the top chamber of the double boiler until the size has melted (no granules are visible). Take care not to overheat and cook the solution, the lower part of the boiler should only brought to a simmer.
Apply to the support, hot for hardboard, plywood and MDF; blood temperature for canvas, paper and sundeala board.
Double boilers are expensive. A cheaper alternative, and one that retains heat without scorching the solution, is a pudding basin over a small saucepan.
* Glue strengths can vary a great deal from supplier to supplier. It is worthwhile to make notes when preparing the solution, paying particular attention to its characteristics when cooled.
For sizing rigid surfaces the cooled solution should be a firm jelly; whilst for flexible surfaces such as canvas it should be a weak jelly which is easy to stir to an apple sauce consistency.
Strengths given are a guideline, experimentation and attention to detail are the key to success.