To make thegesso, you need a chalk and a glue. During the Renaissance,gesso was made with gypsum, which is calcium sulphate. Terra Alba, available from art suppliers today, is a natural gypsum that makes a bright whitegesso.
The idea was that this would serve as a binder for the layer ofgesso or at least might help to prevent the painting from instantly cracking apart if the wood split at any time.
Confusion arises from the fact that the Italiangesso is often translated aschalk, which in English is ambiguous and can be interpreted either as the mineralcalcium carbonate or, in a more faithful translation, ascalcium sulfate (gypsum; the "chalk" used to mark blackboards). In fact, both materials appear to have been used, historically.
In 1955, a water-based acrylic gesso was developed comprised of calcium carbonate, the pigmenttitanium white (titanium dioxide) and an acrylic polymer medium. Modern acrylic gessos come in a variety of materials and mixtures, including coloured pigments, combined with the acrylic polymer base.
“gesso”, inKielitoimiston sanakirja [Dictionary of Contemporary Finnish][1] (in Finnish) (online dictionary, continuously updated), Kotimaisten kielten keskuksen verkkojulkaisuja 35, Helsinki:Kotimaisten kielten tutkimuskeskus (Institute for the Languages of Finland),2004–, retrieved2023-07-02
