SECTION IV. FINISHING PROCESSES 



AFTER the tannage is complete, leather is hung up to dry. 

 In the case of heavy leather this drying must be very 

 carefully carried out in order to obtain a product of satis- 

 factory appearance and saleable qualities. Associated with 

 the drying are many mechanical operations (scouring and 

 rolling) which assist very materially in imparting the desired 

 qualities. After tanning, however, the quality of the final 

 product is most strongly influenced by the amount of grease 

 added in finishing. Some grease is always used in finishing, 

 partly because even sole leather requires some measure of 

 pliability and partly because a coating of oil over the leather 

 during drying prevents the loose tannin from being drawn 

 to the surface of the leather by capillarity, thereby causing 

 dark and uneven patches and a " cracky " grain. The 

 added grease is also a contribution to the " weight " of 

 the finished article a primary consideration for heavy 

 leather, which is usually sold by weight. The finishing 

 processes, indeed, tend to be dominated by this considera- 

 tion, and become a series of efforts to retain as much tannin 

 and add as much grease as are consistent with the require- 

 ments of the class of leather being manufactured. Sole 

 leather does not contain more than about 2 per cent, grease, 

 or its firmness is impaired. Belting leather, in which 

 iderable pliability is needed, may contain about 9 per 

 cent.. whiM 1.. which must be exceedingly 



tough and durable, may contain up to 13 per cent, of fatty 

 mutters. Upper leathers, which need to be soft and pliable 

 as well as waterproof and durable, are very heavily " stuffed" 

 and often contain up to 30-40 per cent, of grease. Sole 

 leather is thus rather distinct from the rest, which are called 

 >tuffed," or " dressed " leatlu 



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