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]Alquantorenosa.[215]Lo accettare il metallo.
[214]Alquantorenosa.
[214]Alquantorenosa.
[215]Lo accettare il metallo.
[215]Lo accettare il metallo.