Fig. 30
FAN FIXED IN CHAMBER
(Howard-Smith system)
Figure 31 shows the Sutcliffe Fan and Heater installed in a tannery. At least two hygrometers should be hung up in a drying-room to determine the amount of moisture in the air.
Chrome Sole Leather
The manufacture of chrome sole leather suitable for ordinary walking boots is of comparatively recent origin, although natural chrome hides were dressed more than twenty years ago for tennis boot soles and other athletic shoes. There can be no doubt of the superior wearing and waterproof qualities of well-dressed chrome sole, but its high price, compared with that of vegetable-tanned sole leather, is against its general use.
Either the one bath or two bath tannage (described on p. 108) may be used, but, on the whole, the one bath method is preferred for the following reasons: (1) Its application is easier; (2) it produces a firmer and less elastic leather; and (3) there is practically no danger of weakening the hide fibres. On the other hand, the two-bath process produces a plumper leather which can, naturally, carry more dressing and command a correspondingly better price. In skilled hands, it is also under better control than the one-bath process, while it is absolutely necessary for the popular pale bluish-grey tint of chrome leather tennis soles.
Fig. 31