166 ANIMAL PROTEINS 



dry, the requisite mellow feel is not obtained. There is, 

 of course, ample scope for variation and ingenuity, and 

 the following processes for blacks and colours must be 

 taken as broadly typical. 



The skins from the reducing bath are first machine- 

 struck, and then immediately neutralized with one per 

 cent, borax until this is thoroughly used up, and the skins 

 are then paddled for many hours in running water. They 

 are again struck out and lightly shaved, possibly after a 

 little drying. There is a tendency to save time by using 

 a stronger borax solution, and by using warm or tepid 

 water, and some factories save borax by washing well 

 first in warm water. If for blacks a common plan is to 

 dye grain and flesh a violet-blue and then black the grain 

 only with logwood and iron. The skins are drum dyed 

 blue with a coal-tar dyestuff, drumming half an hour in 

 the solution at 110 F., and again struck out. They are 

 then paired or pleated, and rapidly passed successively 

 through three vats containing respectively cold weak 

 ammonia, a logwood and fustic infusion at 120 F., and 

 a solution of ferrous sulphate containing a little copper 

 sulphate. The skins must be immediately washed well 

 to remove excess of iron. Instead of this process the skins 

 may be passed through vats containing coal-tar blacks. 

 Instead of blue backing the skins may be drum-dyed black 

 on flesh and grain with either coal-tar blacks or with 

 logwood and iron. In the latter case the skins must be 

 drummed in water for an hour to remove excess of iron. 

 However dyed, the skins are often struck out again after 

 dyeing, and sammed slightly for fat liquoring. Neatsfoot 

 oil is a popular ingredient of the fat liquor. The skins are 

 drummed dry for a few minutes in a hot drum, and the 

 fat liquor added at 130 F., and the drumming continued 

 after the grease has been taken up in order that it may 

 be thoroughly distributed. The skins are struck out again, 

 rapidly dried out, and wet back for staking in damp saw- 

 dust. The staking should be thorough, and, if necessary, 

 repeated when the goods are rather drier. 



