SLACK COOPERAGE 129 



wet end of the kiln (where the highest humidity is maintained) the 

 temperature is maintained from 90° to 130° F. At the dry end the 

 temperature may be 150° or over. 



The period of kiln-drying is about ten days for Northern hardwoods, 

 during which the heading blanks slowly pass from the wet to the dry end 

 of the kiln as fresh material is put in and the dried boards are conveyed 

 to the heading mill. Although kiln-drying is in common practice, at 

 some mills the heading stock is merely air dried in a shed. 



Within the heading mill are the three machines — the jointer, the head- 

 ing turner and the heading press or baler. In some mills the heading 

 boards are planed before they reach the jointer. The heading room 

 should have ample space for the various operations and should be well 

 above the level of the ground in order easily to carry out the refuse to 

 the boiler room and to load the baled heading on the cars with the least 

 efifort. 



As the trucks containing the dry boards are unloaded from the dry 

 kiln, the heading pieces are jointed. This consists of removing any bark 

 or rough or uneven edges and making them smooth and even, so there 

 will be a tight joint or " fit " when the heading pieces are placed together 

 to form the barrel head. This is done either by a saw or a large rotary 

 wheel provided with knives against which the boards are shoved by the 

 jointer until a smooth edge is secured. Experience in the trade, how- 

 ever, has shown that a 5-ft. wheel jointer running 650 R.P.M. and with a 

 2i-in. knife, will give the best satisfaction. An operator well versed in 

 the work can joint 3500 to 4000 sets of heading in a day of ten hours. The 

 heading board should be held firmly and evenly against the jointer to 

 make the best joint. The edge should also be along the grain in so far as 

 possible. If these precautions are not observed the joint is likely to be 

 shattered or rough or uneven. There is a strong tendency to cause 

 unnecessary waste which only an experienced man can avoid to best 

 advantage. 



The pieces next go to the matchers, of whom there are usually two, to 

 keep one jointer and one heading turner busy. These men assemble the 

 heading pieces into sizes approximately of the same diameter as the fin- 

 ished barrel head. From five to six pieces are used for sugar-barrel heading 

 igl in. in diameter. Assuming that the heading turner properly centers 

 the pieces, an allowance of i in. is usually made for trimming. The 

 " goosenecks " or " bats " left after trimming are a good guide to the 

 matchers as to unnecessary waste in matching up boards for the heading 

 turner. The boards are stacked up to a convenient height on a bench 



