SLACK COOPERAGE 123 



The raw material is preferred in the green state as it is manufactured 

 much more readily and is delivered to the mill in the form of logs or bolts. 

 They are accepted down to 8 in. at the small end at some of the plants. 

 A mill pond to clean the logs, thaw frozen logs in winter, serve for storage 

 purposes and to soften the wood for slicing and sawing is in common 

 practice. A log hoist serves to elevate the logs to the main floor, from 

 which point the material gravitates to constantly lower elevations. 



In some mills the logs are rolled on to a deck ; in others they are taken 

 directly to a cut-off saw. In either case, they are inspected and desig- 

 nated for their proper use, the better grade of logs going into staves or 

 hoops, while those containing crooks, knots, checks, and other defects are 

 set aside for heading. Following this inspection they are bolted into the 

 proper length by a drag saw or drop circular saw. The former is used in 

 mills where large logs are the rule and the latter for mills in which the run 

 of logs is small. In one large mill, all bolts for staves are cut into 32-in. 

 lengths, while those for headings are cut into 22-in. lengths. 



From this point in the process of manufacture the bolts are con- 

 ducted on transfer chains or other carriers to the different parts of the 

 mill. 



Manufacture of Staves. 



The larger bolts designated for staves are quartered or halved, depend- 

 ing upon their size, and, if necessary, cut in smaller flitches sufficiently 

 large to yield staves 4 to 5 in. in width. Formerly stave bolts were rived 

 with a maul and wedge, but this method is so wasteful that saws are 

 almost universally used at the present time for this purpose. 



The flitches or bolts are next put through a process to soften the fiber 

 sufficiently to shear into staves. Steaming has been found to be the best 

 method. Well-steamed wood shears about one- third more easily than 

 green or wet wood and yields a brighter and much smoother stave. 

 Wood that is not sufficiently steamed will produce rough, uneven staves 

 that are likely to stain, whereas over-steaming deadens the fiber and, 

 therefore, impairs its life and strength. Elm, cottonwood, soft maple 

 and basswood require much less steaming than gum, beech, hard maple, 

 birch and sycamore. In a mill cutting staves of the last four-named 

 species, the wood was subjected to steaming for twenty-four hours under 

 a pressure of from 100 to no Ib. In some mills boiling the bolts for 

 seven hours is practiced instead of steaming. There is a difference of 

 opinion as to whether boiling or the use of live or exhaust steam is best, 

 but steaming is the most common practice. 



