§ 42 The Preparation of Wax
In order to show how wax is modelled, let us first speak of the working of wax and not of clay. To render it softer a little animal fat and turpentine and black pitch are put into the wax, and of these ingredients it is the fat that makes it more supple; the turpentine adds tenacity, and the pitch gives it the black colour and a certain consistency, so that after it has been worked and left to stand it becomes hard. And he who would wish to make wax of another colour, may easily do so by putting into it red earth, or vermilion or red lead; he will thus make it of a yellowish red or some such shade; if he add verdigris, green, and so on with the other colours. But it is well to notice that the colours should be ground into powder and sifted, and in this state afterwards mixed with the wax made as liquid as possible. The wax is also made white for small things, medals, portraits, minute scenes and other objects of bas-relief. And this is done by mixing powdered white lead with the white wax as explained above.