CHROME CALF 157 



It is not surprising that a light puering is a popular method 

 for attaining this, but there is also a tendency to use 

 artificial bates such as are made from ammonium chloride 

 and pancreatin, together with organic acids, or non-swelling 

 acids like boric acid. Drenching is also common after a 

 preliminary deliming with acid. The skins may be half 

 or two-thirds delimed with lactic acid, rinsed and drenched 

 over night at 85 F. with 6 per cent, bran on the pelt 

 weight. lyess acid may be also used, in tepid water, and 

 the drench made up with 10 per cent, bran and a little 

 pea meal. It is very common to pickle the skins in 5 per 

 cent, alum and 5 to 10 per cent, salt before tanning. This 

 is often of doubtful advantage, but sometimes prevents 

 drawn grain when the goods are moved rapidly into strong 

 chrome liquors. This pickling is said to give fullness to the 

 leather. 



The tannage of box calf is usually by the one-bath 

 process, though the two-bath process gives quite as good 

 a result and is sometimes used. Again, drum tannages 

 are the most popular on account of their speed and the 

 economy of chrome. The practical problem is to use up 

 all the chrome, and to tan quickly without " drawing " 

 the goods. It is, in any case, usual to commence the 

 tannage in a used and nearly spent liquor and finish in 

 a fresh liquor. The most appropriate way depends largely 

 upon local convenience, the number of drums available, 

 supply of labour, etc. In a one-drum system the goods 

 may be started in an old liquor, which is run off when 

 exhausted by the green goods. Fresh stock solution is 

 then added at intervals of an hour or two and the drumming 

 continued till tannage is complete, which is usually in 

 less than 24 hours. The remaining liquor is used to 

 commence the tannage of the next pack. 



In another system the operation is similar except that 

 the liquors are weaker, and the goods are then removed 

 and finished in another drum. A three-liquor system, 

 however, is often combined with a one-drum method ; 

 the goods are thus not handled. The liquors are run off 



