[213] Camicia.
CHAPTER II. HOW THE ABOVE-MENTIONED CLAY IS MADE.
The clay you use is made thus: You take such clay as is used by the ordnance makers for their moulds. It may be found in many places, but preferably near by rivers, for there it has a certain sandiness,[214] still it must not be too sandy, suffice it if it be thin, for the rich clay is delicate and soft, such as is used for small figures, cups, plates, and so forth, but not good for our purpose. Also you will find it in hills and grottoes, particularly round Rome and Florence, and in France at Paris. The clay from the latter city is the finest I ever saw; but as a rule the clay from grottoes is better than that from rivers.
In order to obtain a good result you must let it dry, and sift it carefully through a rather coarse sieve in order to get rid of any pebbles or bits of root or of glass, & such-like things. Then you mix it with cloth frayings, about half as much of the latter as you have clay; and take note that here is a wondrous mystery of the craft that has never yet been used by any but me. When the clay and the cloth frayings are mixed and bathed with water to the consistency of a dough, you beat the mixture up well with a stout iron rod about two fingers thick; and, for this is the secret, you let it decompose for at least four months or more, the longer the better; for then the cloth frayings rot, and owing to this the clay gets to be like an unguent. To those who have not had experience of this little trade secret of mine the clay will appear too fatty, but this particular kind of fattiness in no wise hinders the accepting of the metal,[215] indeed it accepts it infinitely better, & the clay holds a hundred times more firmly so than if it had not rotted. I have used this kind of clay in ever so many most difficult works, all of which I shall tell of in their proper place.
FOOTNOTES:
[214] Alquanto renosa.
[215] Lo accettare il metallo.
CHAPTER III. ANOTHER METHOD OF CASTING FIGURES IN BRONZE OF LIFE SIZE OR A LITTLE UNDER.
Model the figure you wish to cast direct in the clay and rag composition above described. Finish your model most carefully as regards its proportions and its details of design, in fact just as you wish to see it completed. When you have finished your figure, working it part in the fresh & part in the dry clay, as the art may require, and wishing to cast it in bronze, you give it a covering of painter’s foil[216] in order to do which you first take a certain quantity of turps, heat it in a cauldron or pail, and when it is heated to boiling, streak it very carefully all over the figure with a hog’s sable, taking heed not to injure a single muscle, vein or other subtlety, and so very carefully apply your foil. This foil has to be beaten into very fine sheets such as the painters use in many places, as for instance on their canvasses for painting coats of arms; it is well enough known all the world over. Well, you put this foil over the clay figure, and as you have to make a mould of gesso over that, you oil the whole figure well first. Were it not for the foil it would be but ill protected against the humidity and cohesive[217] power of the gesso, but with the foil it is well protected. In this way you work to great advantage, for after the figure is cast in bronze you still have your fine original model before you; and many youths & able workmen can help you clean the bronze figure up, while if you have no model to work to, this cleaning up takes a long time, is little to the poor master’s liking, and has but a sorry result. This was what happened to me when I made the Perseus for the most illustrious Duke Cosimo, and which may still be seen on his Excellency’s piazza. This, which was a figure of more than five cubits high, was made in the first of the two described methods; that is to say, it was modelled in the clay composition, & finished one finger’s thickness under actual size;[218] then it was well baked, and the coat of wax modelled over it as in the case of the nymph of Fontainebleau. After this it was cast all in one piece. In order to remove the core[219] so that the figure might be lighter, I made through the wax a number of holes in the flanks, shoulders, and legs, and at such places where I required them; the result of this was that the core was kept in its place. Moreover, I put over the wax those unguents which I referred to in the case of the nymph of Fontainebleau, then the two or three coats of clay, next I bound it round with the iron of which I shall tell directly, & then I cast it. This casting was, owing to its size, the most difficult casting ever made. But because I am now minded to tell of the casting of a smaller figure, I will not muddle things too much by leaving my theme. Later on I shall not fail to enter upon a little dissertation about my Perseus.
