80 BULLETIN 1136, U. S. DEPARTMENT OF AGRICULTURE 
which will be described later, ordinarily requires a 2-foot spacing for 
satisfactory results. If the boards show a tendency to warp, with 
the spacing employed, the stickers should be placed more closely. 
STICKER SUPPORTS 
The supports necessary for the tiers of stickers should be firm and 
even, and when possible one should be directly under each tier. In- 
dividual conditions, such for instance as the number of tracks in the 
kiln, the kind of piling required for the loads, and sometimes the in- 
genuity of the operator, determine the location of sticker supports. 
Other individual conditions largely select the material for them; 
metal often is cheaper than wood, especially in high-temperature 
kilns, in which wooden sticker supports may have a life of only a few 
trips through the kiln. Naturally breakage of sticker supports us- 
ually occurs in the kiln; it then causes delay and expense in removing 
the kiln car affected, as well as damage to the stock and some- 
times also to the track supports and the heating coils. 
ALIGNMENT OF STICKERS 
Perfect alignment above their supports of. those of the stickers 
that actually carry the weight of the lumber is essentiai, since the 
eccentric loading caused by poor sticker alignment tends to deform 
the lumber. When the number of sticker tiers exceeds the number 
of solid supports that can be provided conveniently, two tiers can 
be started upward from a single support by slanting the pair apart 
until the desired space between them is secured, and thereafter con- 
tinuing them vertically—a third tier of course is run straight up 
as usual, directly over the support. Further, when offset tiers are 
started thus, especially in the case of a single end tfer, enough extra 
stickers should be placed suitably in the lower part of the pile to ex- 
tend the vertical section of the sticker line clear down to the lowest 
layer; these additional stickers are intended to act as separators te 
prevent warping. If only a single tier is inserted between adjacent 
supports in the manner outlined, an arching line of stickers should be 
carried over to it from each support. Figure 13 illustrates good 
practice in stickering a flat-piled kiln charge having insufficient 
points of support. 3 
BOX PILING 
Great care must always be exercised in the actual piling which, on 
account of the importance of proper stickering, may be said to in- 
clude the lumber as well as the stickers. Having in each pile boards 
of only one length is the ideal condition, but where this is impossible 
the stock should be box piled. Im such piling the outer tiers are 
carried up with full-length boards and the short boards in each 
layer are brought flush alternately at opposite ends of the pile, al- 
though bringing all of them flush at the same end is possible. The 
alternate method diffuses the chimney effect incident to tiers of short 
length, both by making the vertical end spaces smaller and by sepa- 
rating them, and thus prevents upsetting the circulation; it avoids 
the concentration of lumber at one end of the pile, with the unequal 
and irregular drying that results, and it also obviates the tendency 
