MODELLING TOOLS
The tools used for modelling are not numerous; two or three modellers, more or less fine and of different curves, (Fig. 12) are sufficient. A special tool, called Pied de Biche (hind’s foot) in allusion to its shape, is also useful in depressing the ground at right angles to the modelling. Modellers may be either of nickelled steel or of brass, provided that the convex side with which the leather is modelled be perfectly smooth. It is better not to use ordinary steel which, when the leather is wet, might cause it to become stained through the rusting of the tool occasioned by the materials used in tanning. It may also be mentioned here that when using acids for patine,[5] steel tools should be kept away from the work. Hydrochloric acid in particular will rust them so badly in a single night as to make them unusable unless they are repolished.