Bianco di San Giovanni is a special kind of lime white pigment first described in literature by Cennino Cennini. Not to be confused with simple chalk, Bianco di San Giovanni, as Cennino Cennini reports, is dried lime which is reduced to powder and then immersed in the water and left to dry in the sun. Therefore Bianco di san Giovanni is calcium carbonate plus calcium hydroxide. Preparation of Bianco San Giovanni is demonstrated in detail in Buon Fresco Foundations: Vol 3 - Pigments & Paint video tutorial by iLia Fresco (Anossov).
The one can make white paint directly from Aged Colonial Slaked Fresco Lime Putty by screening it with cheese cloth and diluting with water to the paint consistency, however resulted paint will be thicker then Bianco di San Giovanni. At the FrescoSchool.org we mainly use Bianco di San Giovanni to prepare special colors such as historic flesh-tone color, Cinabrese, by mixing it with other pigments in dry form.
Unlike most of the fresco pigments in our Classic Fresco Pigments Set, dry Bianco di San Giovanni must be ground with water into paint each day fresh - it shall not be stored as paste. Our Bianco di San Giovanni is fine ground one .