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KILN DRYING HANDBOOK 95 
A. solution scale, capacity 20 kilograms, sensitive to 1 gram; two scale 
beams, one graduated to 100 grams in 1-gram units, the other graduated to 
1,000 grams in 100-gram units; counterpoise and loose weights. 
One drying oven (electric or steam), inside dimensions at least 10 by 12 by 
10 inches, to operate at 212° EF. Thermostatic control for the oven accurate 
to within 2° F. 
One 10-inch slide rule. 
One smoke machine with concentrated hydrochloric acid and strong ammonia 
water. 
Two flash lamps; spare batteries and lamp bulbs. 
If hot end-coatings are to be used, a kettle and a hot plate or a stove will 
be needed. 
A small motor-driven band saw for cutting samples and sections will in many 
eases prove an excellent investment. For high-temperature kilns two maxi- 
mum-reading wet and dry bulb thermometers, 60° to 220° F., graduated every 
second degree, will be found very useful. 
Miscellaneous tools, such as screw drivers, pipe wrenches, pliers, a saw, a 
hammer, and a rule. 
For identification purposes each instrument should be numbered 
before it is put into service. A metal tag attached to the casing or 
to the support is convenient for this purpose when numbers can not 
be stamped or etched directly on the instrument itself, 
AIR SEASONING 
Discussion of the air seasoning of wood falls outside of the prov- 
ince of this publication, except in so far as a knowledge of it is 
essential to the kiln operator. Much of the lumber dried in kilns, 
especially hardwood lumber, however, is first air-dried, either at the 
sawmill or at the manufacturing plant, and the quality of the finished 
product depends in no small measure upon the care taken in the pre- 
liminary air seasoning. 
Piling correctly for air seasoning must accomplish a number of 
things: It must provide proper air circulation, it must offer suitable 
protection from sun and rain, and it must keep the boards straight and 
flat while they are drying. If these things are accomplished, the 
best drying will result, and drying defects will be at a minimum. 
Among such defects may be mentioned stain and decay, end and sur- 
face checking, and warping. 
No one rule will apply to all weather conditions and to all classes 
of stock; often, however, no special precautions have to be taken to 
prevent too rapid drying, while on the other hand every effort should 
be made to secure ample air circulation through the pile. 
ns following general principles will apply to most seasoning 
yards: 
Foundations for lumber piles should be firm, and level in one di- 
rection and properly pitched in the other. Standing well above the 
ground, preferably high enough to give a 12 to 18 inch clearance 
above the ground at the lowest point, they should provide adequate 
support for each row of stickers and keep the lumber entirely free 
from decay. Free circulation of the air under the stringers and 
around all parts of the foundations must be secured. 
_ Pile widths should be kept small when possible. A 6-foot width 
is an excellent minimum for most hardwoods. Softwood piles can 
usually be wider—8 feet and upward. When softwoods are stickered 
with stock (self-stickered) instead of with special stickers the width 
