Over the years I’ve tried various chalks (calcium carbonate) and gypsum (calcium sulphate) to make gesso. I’ve come to prefer a fine marble dust, for hard to define reasons: it’s a bright white, has the right “feel” of hardness to me, and admittedly I probably like the idea of working with ground marble.
Within the two general categories of chalk and gypsum there are many different products available, differentiated by source, type of grinding, processing, natural coloration, etc. Is it correct to say that these properties don’t affect the quality of the gesso, rather they merely reflect individual artist preference (such as my own mentioned above)? Are these differences actually perceptible (aside from the obvious visual one of coloration)?
Finally, is there any reason to make a egg tempera ground (final layer, not initial) using a medium or coarse grind chalk or gypsum, or would that increase porosity/absorbency too much?
Thanks,
Koo Schadler
Thanks, Brian.
I would imagine that there is a limit as to how fine or coarse the powder is ground before it becomes problematic. Too fine may make it hard to have the particles fully dispersed and too coarse could create a ground that is too rough to cleanly apply strokes of paint. However, for the most part, the choice of the type and grind of calcium carbonate or hydrated calcium sulfate is up to personal preference.