VENEERS 



97 



The degree of heat and length of the boiling period should be governed 

 by the hardness of the wood, its degree of dryness, porosity, toughness 

 of the fiber, size of logs, etc., but little attention has apparently been paid 

 to these matters. 



In practice, the following periods of boihng are commonly used : 

 From one to two days or up to forty-eight hours for the oaks, fifteen to 

 eighteen hours for yellow poplar, from twelve to twenty-four hours for 

 red and black gum, from twenty-four to thirty-six hours for elm, ash, 

 birch and maple, Douglas fir and western pine. Temperatures of from 



Photograpn by Nelson C. Brown 



Fig. 1 8. — A rotary veneer machine showing the lugs on which the log is turned and the veneev 

 knife immediately back of the man. Photograph taken in a California veneer mill 

 cutting western pine {Pinus ponderosa). 



i6o° to 220° F. are maintained. If oak is boiled too long it becomes so 

 hard that it is very difficult to cut it. Yellow poplar when over-boiled 

 produces a rough veneer, showing that the fibers have been crushed too 

 much rather than being cut sharply. Cottonwood and basswood do not 

 require boiling. 



After boiling, the bark is removed. This is done by splitting the bark 

 lengthwise. The bark then drops off easily after being loosened in the 

 boiling process. 



The bolts are taken over to the veneer lathe, which has two large drive 



