62 



ANIMAL PROTEINS 



also have three layers (60, 65 and 80) of 2, 3 and 4 weeks 

 respectively. 



The course of the liquors is shown thus : 



Butt layers 

 (and -!- extract) 



^ 



Belly layeis 

 (8o-6o) 



Butt suspenders 



Offal drums 



Butt suspender 

 Handlers ( + extract) 



I 



Shoulder layers 

 (8o-6o) 



Offal handlers (55-40) 



* 



Offal suspenders (40-! 8) 



Drain 



The tanned butts are piled for 2-3 days, sometimes 

 rinsed to remove dusting material, and then scoured either 

 by machine or by drumming with sumac and extract. This 

 removes bloom, but causes some loss of weight. " Vatting " 

 or " bleaching " now follows, in which it is attempted not 

 only to bleach the colour of the leather, but also to impart 

 as much weight as possible. The vat liquor is made several 

 degrees stronger than the last layer by means of quebracho 

 bleaching extract and good coloured chestnut or myrabs 

 extract. The liquor is kept warm by a steam coil, at about 

 100 F., but not much more without risk. The goods 

 remain in the bleach liquor 2-3 days and are then horsed or 

 suspended to drain. Sumach is sometimes used in the vats. 

 A new vat liquor must be made up after some weeks' use. 

 The goods are sometimes rinsed in weak sumac liquor before 

 vatting to get good penetration, and sometimes after to 

 ensure good colour. 



The butts are next oiled and hung up in a dark shed 

 and allowed to dry slowly and evenly to an " india-rubbery " 

 consistency and rather slimy feel. They are then " struck 

 out " by machine, wiped, re-oiled and again hung up to 



