It is an animal glue obtained through boiling the skin and the cartilage of oxen, rabbit, goat or other animals. From purified carpenter’s glue, gelatins (see Gelatin), that are amply employed in painting techniques, are obtained. The qualities of the various carpenter glues is based on the ingredients used and the techniques employed in its preparation. Its use in painting is amply documented. Cennino Cennini (end of the 14th Century), defines kid glue and furnishes a recipe for its preparation, underlining the qualities and explaining: "This is a glue used by painters, by saddlers, and by ever so many masters…. for gessos, for tempering colours, making lutes, tarsias, fastening pieces of wood and foliage ornament together, tempering gessos, doing raised gessos; and it is a good for many things."