ber that is in the pile, and 24 combine the two by using special roofs for the better grades and lower grade lumber for lower grades. One reply indicates that roofs are used only in winter (southern pine), as the lumber dries faster in summer without a roof, and three (southern pine) use no roofs. An overhang at the front of the roof of 1 foot or under is used by 26 mills, while 10 leave the roof flush, 14 use an overhang of 1 to 2 feet, and 4 an overhang of 2 to 4 feet. At the rear end the roof is left flush by 11 mills, 4 use an overhang of 1 foot and under, 2 an overhang of 1 to 2 feet, 14 an overhang of 2 to 4 feet, and 3 an overhang of 4 feet and over. Side overhang is less commonly used, and 28 mills leave the roof flush at the sides; 7 use a side overhang under 4 inches, 5 make it 6 to 12 inches, and 2 make it 24 inches. FIGURE 22.-Lumberyard alley showing a common form of roof, though often more front overhang is used. Photograph courtesy of Forest Products Laboratory There are 25 mills using roof boards of the same length as the pile and lapping them in two lengths, while 5 provide longer boards in a single length for special lengths, and 12 use both methods. At 28 mills winds are not strong enough to require any fastenings for roofs, 11 mills tie the roofs down with lath yarn or wire, 10 weight them down with heavy crossers, and 4 fasten them down with crossers secured at the ends by double iron hooks which hook over the end of the crosser and down into the side of one of the pile layers of lumber. Figure 22 shows pile roofs. SIDE PILING The rain-protecting feature of the roof is modified in one form of piling that is in some cases used and preferred, known as side piling. (Fig. 23.) The piles slant back from the alley, as usual, but as they are piled sidewise to the alley this slant is sidewise and not endwise of the pile. The recommended slant is also a little steeper, 1 foot to 7 feet, instead of 1 foot to 12 feet. For this piling the lumber is preferably of even widths and is piled in vertical tiers, with spaces between the boards, so that any moisture draining from the sides of the boards falls to the bottom of the pile. Roof boards are of the same width as the boards in pile and spaced apart the same way, protecting the pile from the sun but allowing rain to run through into the tier spaces. The argument made for this form of piling is that rain does not hurt lumber while air-drying if it runs off promptly, as it does in this form of piling, while any rain getting into end-piled stock runs down the board to the sticker, soaking the sticker crossing and washing against it any sawdust that may be on the lumber; and such accumulations of sawdust above the stickers are said to be a source of degrade from decay in some cases. Further, the ends of the boards are at the sides of the piles, which are spaced sufficiently close to protect the ends from sun and wind, resulting in less end check. FIGURE 23.-Customary method of side piling even-width lumber Side piling seems to be regarded as of little practical importance by the lumber manufacturers, most of the replies received indicating that it is not used at all. It is used a little at one California pine mill and at one southern pine mill, but for what kind of product is not stated. It is used in piling shorts at one redwood mill and at one California pine mill. Small timbers are piled sidewise at one southern pine mill but are given end slant instead of side slant; and this seems also to be the kind of slant given the export grades which are side piled at three other southern pine mills. Damage of lumber in pile by accumulations of sawdust above the stickers is somewhat rare and confined to certain species in which the sawdust tends to cling to the boards; in such case side piling might be tested to determine whether it would produce any better results than end piling. It is at present in very limited use, but that may be because it has had limited trial. Whether it proves better than end piling with adequate roofs will depend largely upon species, climate, and season of the year. Pile roofs, especially if they have overhang, require some sort of fastening to hold them in place; this is usually arranged by putting crossers on top of the roof boards and fastening them down with wire tied to sticker ends in the pile. A special iron hook is often used, having a square hook at both ends, one end of which is hooked over the roof crosser and the other forced in between the boards of the pile in such wise as to put the hook under considerable tension. This must be thoroughly done, as shrinkage of the lumber in seasoning tends to loosen the hook. Another important consideration in seasoning some species of wood is a tendency to warp or cup near the top of the pile, because there is not enough weight of lumber above to hold them straight. This damage can be materially reduced by fastening the roof down firmly enough to bind the top layers of lumber and hold them flat; if tying down is used, the ties should be given enough spring tension to hold them tight after the lumber begins to shrink. A practical plan would be to weight the top of the pile with enough heavy crossers to accomplish the result. Manufacturers should not accept degrade from this source when a little experimentation would develop an efficient way to overcome it. Most of the damage to lumber from warp and twist occurs either in the top layers of the pile or at ends of long boards projecting too far at the rear of the piles, and both kinds of damage are largely preventable. SPECIAL PILE PROTECTION In some kinds of lumber, and particularly in thick wide uppers, it is profitable to use special expedients to prevent and reduce end checking. These include end cleating or end painting the ends of each piece before piling, or protection of ends by special shields. End cleating is used mostly on high-grade export stock. A narrow strip is tacked on the end of the board with small nails, completely covering the surface and reducing the rate of drying through the end of the wood. End painting is also fairly effective. Ordinary red paint is sometimes used, but hardened gloss oil fills the pores of the wood better. End painting does not fill log checks already in the lumber, and these may extend farther and open wider. End painting of logs instead of lumber would be more effective in this respect. One company sprays melted paraffin on the ends of thick uppers. Special protection to ends of lumber piles usually consists of standing a row of cull boards along the ends of the pile, forming a screen which shuts out sunlight and partially shuts out the wind. Sometimes two pieces are stood up and the boards nailed crosswise upon these, and sometimes the shield is close to the pile end instead of slanted out at the bottom. (Fig. 24.) Shutting off the breeze at the end of the pile has little effect on general seasoning rate, because air gets into the pile chiefly from the sides, between the sticker lines. End coating of timbers at the sawmill is modified by the fact that 35 mills report them as cut to special order only, in which case they may not get into yard piling at all; 13 other mills carry more or less timbers in stock, and 7 mills use end coating to some degree on heavy timbers. Thick upper-grade lumber is also sometimes end coated and 8 mills report this practice; end cleating is reported as being used on certain special grades by 11 mills. The shielding of piles of special grades of lumber is also reported by 17 mills; most of them merely stand up low-grade boards, while some nail them into FIGURE 24. Cleated end-shield protecting ends of pile of 3-inch cypress. panel shields, and one manufacturer constructs these of horizontal slats laid louver fashion to obstruct sun but admit the breeze. AIR SEASONING AS AFFECTED BY LIABILITY TO BLUE STAIN Practically, blue stain is an air-seasoning defect, though technically, of course, it proceeds from the attacks of various kinds of fungi. This fungus is different from those that produce decay in wood, as it does not break down and feed upon the wood substance itself but lives on the soluble contents of the cells of sapwood, and so affects the heartwood little or not at all in many species of wood affected by blue stain. The fungus threads do some damage to cell walls by penetrating them to reach the contents, and so weaken the wood, but not to an important degree. These fungus threads are brown in color, but in combination with the color of the wood itself are toned to the blue appearance of the stained wood. After a time fruiting bodies of a black, powdery nature appear upon the surface of the wood; each body consists of an onionlike base from which rises a slender stem, ejecting spores at its tip. Lumber may show heavy stain infection without any development of fruiting bodies, if surface drying occurs early enough to prevent their development. Spore infection comes mostly from wooden rubbish on the ground, or in other locations where it remains moist and gives the fruiting bodies ample opportunity for development. Logs in the woods become infected through their exposed ends, and the stain may pene FIGURE 25.-Pole stacking to reduce blue stain, in a southern sawmill yard. trate into the log before it is sawed into lumber; infection may occur at any time from the log to the pile, or after the lumber is in pile, from spores floating in the air. If lumber comes in contact with wood containing fungous threads or roots they can grow into and thus infect it without the agency of spores. Stain-infected stickers or foundation timbers cause infection in this way. Lumber may have active stain within it at the time it is sawed, and such stain will continue to develop in its interior as long as there is sufficient moisture to support it. New infection of the lumber can occur only on the surface and will be prevented if the surface is dried to a sufficient degree before the infection has had time to develop. For pole piling a horizontal pole is supported on posts at the desired height above the ground, and the lumber is leaned edgewise against this pole from both sides, the boards crossing near their tops above the pole, and mutually supporting each other. (Fig. 25.) The bottoms of the boards should be off the ground a foot; if there are long projecting ends above the crossing, they will dry |