Where a sawmill makes any feature of timbers it is apt to carry a yard stock of the sizes most called for, and the length of time they remain on the yard will depend upon relation between supply and demand. Timbers are usually piled sidewise to the alley for convenience in handling them in and out of pile, whether wagons or derricks are used in moving them. It is not considered necessary to give the pile any horizontal slant either lengthwise or sidewise, though often an endwise slant is provided. Some care is used to provide the bottom timbers of the pile with several points of level support, usually at least four; the timbers are spaced somewhat apart, and stickers are used over these support points to hold succeeding layers. The stickers are often 2 by 4, though sometimes smaller.

Timbers usually surface check as they dry out, depending upon the species, and also usually develop end check to a more serious extent than smaller sawed sizes. This can be reduced considerably by painting the ends with a suitably thick preparation. Of a number of coatings developed by the forest products laboratory, the best cheap coating for brush application cold consists of hardened gloss oil, 100 parts, thickened with 25 parts of barytes and 25 parts of asbestine. (Technical Note 186.) More common use of end coatings by lumber manufacturers, not only on timbers but on other thick stock, would avert large wastes of material caused by end checking. Stain and decay in the ends of unmanufactured saw logs can also be reduced by an early use of such coatings.

SEASONING OF SAWED RAILROAD TIES

Some railroads follow a practice of air seasoning ties and other material for at least a year before preservative treatment, while at other railroad treating plants 60 days at a favorable season of the 'year is considered sufficient on some species. The manufacturer of sawed ties is usually not directly interested, because he makes shipment weekly as the ties are accumulated, and the railroad attends to the air seasonings afterwards. Where ties pass over foreign lines before reaching the buyer's rails, mill seasoning may be required. The buyer will in such cases usually specify how they are to be piled for air seasoning; usually square piling with 7 ties in a layer, then 2 crossties, then another layer of 7 ties. This is known as 7-2 piling, allowing a little spacing between ties; for closer piling 8-2 is used, or sometimes 9-1. This, of course, means 9 ties in a layer, and only 1 crosstie at one end, the next crosstie being placed at the other end to keep the pile square built. (Fig. 32.)

AIR-DRYING OF LATH

Lath are always bundled green from the saw, and these bundles are cross-piled in square piles 8 or 10 feet high on the mill yard, and under average conditions get perhaps 60 days' seasoning before shipment. This is desirable to reduce the weight for shipment on species which load the minimum weight of dry lath in a car, but sometimes it does not call for thorough drying. As far as fitting for use is concerned, the seasoning tolerance is very broad, and some builders

29055°-29

prefer to nail lath in a practically green condition. Thorough seasoning is neutralized by the thorough wetting which is always given lath before plaster is applied to them; and lath are usually piled outdoors in storage to maintain a relatively high moisture content in the wood. Some manufacturers kiln-dry laths. (Fig. 33.)

AIR-DRYING SMALL-DIMENSION STOCK

The cutting of small sizes of dimension stock in both hardwoods and softwoods is a specialty in which a great many mills have not

FIGURE 32.-Showing method of piling ties with only one crosser
to the course. This method is called 7-1 or 8-1, depending
upon whether there are seven or eight ties to the layer. Photo-
graph courtesy of Forest Products Laboratory

yet engaged; but its use is growing, because it effects a larger utilization of the log in producing stock and further economies in use of the stock by the woodworking factory; it eliminates the waste in cutting such sizes at the factory from shop or factory grades of lumber, which involves a loss of 25 to 35 per cent of footage. While a square-edged factory may turn out only 65 per cent of the cuttings, the same board before being edged can often be cut into a full footage of such cuttings, the loss through defects being overbalanced by the gain in the wany edges of the board. Parts of the tree which will not make factory lumber will often work out a considerable

footage of factory cuttings; and the sawing of small factory dimension at the sawmill is altogether a factor of much larger utilization than the sawing of factory lumber, with a heavy sawmill waste, to be shipped to some factory and there converted into cuttings with a considerable additional waste of wood on which freight has been paid.

The chief difficulty has been in correlating production and demand and thus establishing a stable market for sizes standardized as far as possible to avoid multiplicity of detail. Another difficulty has been that while seasoning

degrade developing in a board may leave a considerable percentage of it usable, degrade in a piece of cut dimension may render it worthless. A reasonable amount of end checking may be compensated by cutting the piece overlong, but warp is more apt to develop in seasoning small sizes than in larger boards.

Because of the difficulty of seasoning wood in small sizes without checking and warping, dimension material is sometimes cut into unedged planks and seasoned in this form, before being cut into final sizes. Such seasoning however, is usually by kiln-drying; unedged lumber is being sawed and air seasoned at small New England mills for later use as box material, and Figure 34, taken in a northern yard, shows another instance of the air-drying of dimension material in the form of boards "sawed alive."

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The most common forms of air-dried dimension are squares" mostly 6 by 6 inches and under and 2 to 4 feet long, though various kinds of "slats" or oblong, cross-area stock are also air-dried. Most of these pieces are cross piled in square piles, usually with full layers in both directions as crossers, if faster drying is desired. A great deal of such stock is seasoned in open sheds; some of it is piled outdoors, with sometimes an attempt at roof protection. Such ricks or piles are usually arranged in close-ranked rows and are piled from 7 to 10 feet high. Such stock is often end-coated, and sometimes piles are shielded where exposed to direct sun.

At softwood sawmills random-length short material is often box piled for air-drying, with several lengths of stock in the length of the pile, the ends butted together on interior stickers placed the right

FIGURE 35.-Squares made up into bundles with short stickers and tied with a wiretying device. Note use of protecting blocks to keep wire from cutting in at corner of bundle. Photograph courtesy of Forest Products Laboratory

distance apart to accommodate the length variations; and such piles air-dry usually with less end damage than would occur in shorter piles.

At some dimension plants a practice has been adopted of bundling dimension into packages with cross stickers and tightly tying with

of Forest Products Laboratory

FIGURE 37.-Piles of dimension, showing protection of ends with heavy paper. Photograph courtesy of Forest Products Laboratory

a wire-tying machine. (Fig. 35.) These packages are then ricked for air-drying. As the wood dries and shrinks the wire ties tend to loosen but may be tightened again with a device which puts kinks in the wire and thus shortens it. Figure 36 shows the method of outdoor piling of such bundled material.

Figures 37 and 38 show two methods of piling squares to reduce end checking-in one case by shielding the ends with heavy paper, and in