Ancient Stucco White

Probably a few know that ancient stucco as it was used by Greeks and Romans, was a white color proper medley coming from slaked lime and white marble or stone powder mixture. At that time coloring wasn't done during the mixture, but afterward, decorating still fresh plaster with colors.

Giorgio Vasari (Painter, architect and art writer, Arezzo 1511 - Florence 1574) wrote about Giovanni from Udine, the great artist Raffaello's pupil, stucco decorator master, a specialist in 'grotesque' decorations:

«finally crushed pieces from the whitest possible marble, made it in tiny powder and sifted it, so he melted it with white travertine lime, and found that without any doubt it was the way to make the true ancient stucco with all those parts he wished in it»
(Travertine: calcareous rock coming from soluble calcium bicarbonate rich waters deposite
that becomes insoluble bicarbonate)

Again Giorgio Vasari describes roman stucco composition:

«in a stone mortar they crush marble chips; they can't use if not white lime, made by marble or travertine chips; and instead of sand they would take crushed marble, tiny sifted and melted with lime, proportion would be two parts of lime and one of crushed marble and would make thicker and thinner, as they would like to work it.»

To 'whiten' at that time meant to plaster walls with stucco (white faux finishing).
Faux finishing: (stucco prepared with white marble powder and slaked lime). Nowadays with faux finishing we mean a finishing plaster basically made by stonelime and marble or stone powder. It is so called (faux finishing or marmorino) because it is the best marble representation both in composition and in final look.