‹‹‹ Vitr. 7.3.6 | Table of Contents | Vitr. 7.3.8 ›››
7When the work is well beaten, and the under coats made solid, and afterwards well smoothed by the hardness and whiteness of the marble-powder, it throws out the colours mixed therein with great brilliancy. Colours, when used with care on damp stucco, do not fade, but are very durable; because the lime being deprived of its moisture in the kiln, and having become porous and dry, readily imbibes whatever is placed on it. From their different natures the various particles unite in the mixture, and, wherever applied, grow solid; and when dry, the whole seems composed of one body of the same quality.
7And further, such walls, owing to the solid foundation given by thorough working with polishing instruments, and the smoothness of it, due to the hard and dazzling white marble, will bring out in brilliant splendour the colours which are laid on at the same time with the polishing.
These colours, when they are carefully laid on stucco still wet, do not fade but are permanent. This is because the lime, having had its moisture burned out in the kiln, becomes porous and loses its strength, and its dryness makes it take up anything that may come in contact with it. On mixing with the seeds or elements that come from other substances, it forms a solid mass with them and, no matter what the constituent parts may then be, it must, obviously, on becoming dry, possess the qualities which are peculiar to its own nature.