Green Lumber to be dried should be end coated with aluminum paint or other commercial end coating. immediately after sawing to prevent large losses from end checks and splits. End coating is not too effective when applied after the lumber has begun to dry. Lumber should then be stacked in the kiln with a one foot clearance on either side of the stack (between the north and south walls and the stack) to permit adequate air circulation, and in neat layers, seperated by stickers or spacers running perpendicular to the lumbers length. The lumber in each layer must be uniform in thickness. If the sawn lumber is quite variable in thickness, one or both faces of the boards should be planed or jointed before drying to obtain a uniform thickness to reduce warping during drying. Planing also reduces the risk of face or surface checking in oak. Green lumber will begin staining immediately if not stacked for drying.Stickers also must be uniform in thickness. Stickers must be dry and often are 3/4" thick,1 1/4" wide, and as long as the lumber pile is wide. Stickers are placed perpendicular to the boards length, every 12-18" along the lumbers length. The stickers are placed directly above the stickers in the lower layers.
If the lumber is of varying lengths, shorter boards are staggered by alternating them from one end to the other with the longest pieces always on the outside edges. The ends of every board should be supported with a sticker.
The stickers hold the lumber flat, preventing warp, while allowing air to circulate through the pile and dry the lumber.
While the lumber is being stacked, several boards must be cut (see next section) in order to provide sample pieces that can be periodically checked for moisture and can be observed for possible drying losses. After the lumber is stacked, another layer of stickers is laid down and a black painted sheet of plywood is laid on top to act as a cover. The cover can be weighted with rocks or other material to help hold the top layers flat.
When drying lumber it is desirable to monitor its moisture content to avoid drying too rapidly and developing degrade. Moistures are measured from the sample boards and the daily rate of loss is compard with the "safe rate" for that species. When drying is too fast,it may be necessary to block off part of the collector, or else turn the fans off and open the vents during the hottest part of the day. (If the fans are turned off, it is possible to develop temps around the fans that could melt the plastic components.)
Once the lumber is dry, it must be stored in a dry location (approxinmately 30 to 40% RH) to avoid regaining moisture. It may be stored in the dryer until more green lumber will be dried.
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