PUTTING UNUSED WOOD TO WORK

C. V. SWEET.

Every time a saw chews through a log, it spits aside sawdust. Whenever a planer dresses the roughness off a board, it throws off shavings. Square-edged lumber is made only at the cost of slabs, edgings, and trims. For every log put through the sawmill a considerable tonnage of wood fiber is left in the forest. Even the digesters of pulp mills disgorge as unusable sizable quantities of the wood fed into them. And so it goes with nearly every operation concerned with harvesting and converting trees into useful things.

Those unused materials generally have been called waste, not in the sense that they signify neglect or carelessness but in the sense that they are not economically usable. If there is use for them, the margin of profit may be discouragingly narrow, the necessary investment for equipment may be prohibitive, or the expense of handling and hauling the raw material to one point may be excessive.

Theoretically, there is a use to which practically every type of unused wood is or can be put. The problem is in finding profitable ways of doing it on an adequate basis.

Only in relatively recent years have we come to regard those unused forms as important to our national economy.

Without quite yet realizing it, we have become so desperately dependent upon our forests that failure to get the maximum use from the annual timber harvest becomes increasingly vital.

Is this unused wood close to locations where it can be put to use? Just why does a waste occur? Are we making any headway in efforts to use it?

RESIDUE occurs everywhere that wood is utilized to make things, but much of it is in remote and scattered locations. It happens for various reasons. One of the most basic is that nature did not design trees wholly, or even primarily, for man's use. Nature made them round, partially defective usually, with buttressed butts and with much of their content in branches and tops. We use only the round trunk, as a rule, and for the most part saw it into strips with squared edges to remove the bark, although veneer is peeled off like paper from a roll and the pulp-mill chippers swallow the whole barked log. But even the trunk has knots and some other defects which, for many purposes, must be cut out.

The most obvious accumulations of material discarded in processing occur at small sawmills, although back in the woods there may be even more. To the layman, the great heaps of sawdust and other scrap at the sawmills loom as an impending evil and a bad waste. The fact is, however, that those piles of refuse are in large part unavoidable even with the most efficient sawmill equipment. The finest saw inevitably chews up some of the wood as it bites through the log.

At sulfite pulp mills, only the cellulose in wood is extracted for manufacture of high-quality book and magazine paper, rayon textiles, plastics, and other chemical products. Roughly, a third of the chemical constituents of wood, known as lignin, are discarded because there is no good use for them. Lignin has thus far defied the efforts of a small army of chemists to make much profitable use of it. Not only is it unused; it pollutes the stream into which it is dumped. Some cellulose fiber is lost with the lignin.

At first glance, rotary-cut veneer, from which most softwood plywood is made, looks like an efficient way to utilize logs. Veneer bolts are mounted on a lathe that rotates them while a stationary knife cuts off a continuous ribbon of veneer. But logs are not perfect cylinders of perfect wood. A good deal of veneer has to be removed piecemeal before the log becomes a cylinder that yields a continuous sheet of veneer as it revolves against the cutter blade. Knots, cross grain, and other defects take a heavy toll, and, finally, there is the unused core of the bolt, which is too small for veneer cutting. By the time the veneer is clipped, trimmed, graded, patched, and otherwise readied for the plywood presses, some 40 to 50 percent of the log has been lost.

These and related products including railroad ties, cooperage, mine timbers, shingles, and on down to tongue depressors and pencil slats make up the output of the wood-using industries. In total, the discarded material from these industries bulks almost fantastically large each year.

Follow the lumber from the sawmill and you find still more loss. There are, for example, the cut-offs and degrade that result from seasoning. As lumber dries, considerable amounts are checked, warped, split, and honeycombed. Knots loosen and fall out. Some of the lumber becomes infected with decay. At the planing mill, more sawdust and shavings; at the building site, discarded ends, broken pieces, and warpage and splitting due to faulty handling and piling. In the furniture factories and millwork plants, the same processing residues occur.

A hundred million tons of unused wood each year-60 million tons of cellulose in a cellulose-hungry world constitutes an almost untouched backlog of raw material that challenges the ingenuity of Americans.

After the piles have been out in the weather for a short time they become practically useless except where they can be used in mixture with poisons to control grasshopper plagues. Ultimately they may find usefulness in some areas as soil-conditioning materials to improve the physical make-up of soils.

Sawdust fresh from the log has present and potential values as fuel for specially designed furnaces and burners. Hickory, oak, maple, and birch can frequently be shipped over long distances for use in smoking meats at packing plants.

If the sawdust is from dry wood cut at factories, it has a larger range of use possibilities.

Obviously, this unused wood occurs in comparatively small rivulets all along the harvesting and production lines. But the rivulets never run into one big reservoir that can be conveniently tapped. There is tremendous variation in the kind and form of the residues that occur, and this diversity complicates the task of utilizing them.

The task, of course, starts in the woods. More efficient harvesting methods are constantly being devised. New, fast-working, labor-saving equipment for cutting, skidding, loading, and even bundling has speeded forest operations to the point where it often has become profitable to relog after primary logging and to salvage much cull timber for lumber and pulpwood that would not pay its way with the ordinary logging equipment.

In ordinary logging, only the trunk of the tree is taken out. Tops, branches, and stumps are left behind to be burned or eventually to decay. Sometimes the woods operators can find markets for a part of this refuse. Tops of felled trees can sometimes be sold for pulpwood along with defective trees, thinnings, and the noncommercial species. Some refuse can be used to make charcoal where markets exist. Short logs of good material can be sawed into boards, squares, barrel staves, and numerous other small products. Some short lengths cut from between branch whorls may be suitable for box veneer and paper cores. Stumps, crotches, and other parts of some species provide figured veneer. Forest litter finds markets with local nurseries as mulching material. Branches can be used in such items as rustic furniture and fencing.

Everything that can be used in the form of sawed and solid wood products should be recovered first. Recovery for pulpwood and fiber products is next in order for areas near established mills.

Sawmills, too, have undergone extensive changes. In the older forest regions, many of the big stationary sawmills have shut down and have been supplanted by smaller portable mills that can be moved from one locality to another. Previously looked upon as a headache to lumbermen and foresters, portable mills are undergoing revolutionary development and are playing an increasing role in our forest economy; they require less investment, they can be moved easily, and they can operate economically where timber resources are thinner and more scattered. The design and operation of small sawmills are being studied for ways in which to make them more efficient.