ing wane can be used, not only as boxing and crating material and in construction work, but also in planing mill products which are tongued and grooved, and in material such as ceiling in which wane will not show on one surface. The volume of slabwood may be reduced by efficient sawing equipment and by care on the part of the sawyer.

EDGINGS. The volume of edgings produced at a sawmill depends largely on the species, the taper of the log, and the quality of the lumber. The edging waste is greatest when lumber is sawed from logs having excessive taper. This is especially true when applied to softwoods, but is not so applicable to hardwoods, since hardwood grading rules provide for tapering boards. The edging waste in softwoods is also greater because of the practice of sawing even widths only. This practice is not extended to hardwood manufacture.

FIGURE 5.-Load of carefully culled slabs which is to be carried to a small-dimension plant for remanufacture. The poorer slabs and edgings not of value for further manufacture are used for fuel

The tendency on the part of the consumer to insist on long lengths when short lengths might be used produces unnecessary edging waste, since this type of waste is usually excessive when manufacturing longlength lumber. A large amount of edging waste is also produced by efforts to raise the grade. Edging waste may be reduced by using unedged boards-flitches-in cases where the lumber is to be used in the manufacture of small dimension stock. By this practice it is possible to utilize a large percentage of the material which would normally be wasted. Crosscutting logs into bolts results in a similar saving.

TRIMMINGS.-Trimming waste is produced by the trim saws and the timber butt saws and at the planing mill by the cut-off saw. This type of waste is greater in the manufacture of softwoods because boards are trimmed in multiples of 2 feet. Hardwoods may be

trimmed to odd and fractional lengths, thus materially reducing the trimming waste. However, it must be remembered that according to present grading rules the percentage of odd lengths is limited. A large quantity of squared timbers is exported to Europe from the United States. In Europe these timbers are sawed into lumber which is trimmed in multiples of 1 decimeter (equal to 4 inches). The American custom of cutting felled timber into convenient log lengths, instead of cutting to such lengths as will permit economical manu

FIGURE 6.-Thick-gauged saws cause excessive waste in the form of sawdust. The above diagrams indicate the number of 1-inch boards and the percentage of actual lumber secured from a 12 by 12 inch square when manufactured with saws having teeth the size of those indicated over each diagram. (Courtesy of the E. C. Atkins Co. (Inc.), Indianapolis, Ind.)

facture at the mill, is responsible for large amounts of trimming waste. Felled timber should be crosscut on quality rather than on standard log lengths. A good illustration of this better utilization practice is shown by various slack-stave operators in the Shenandoah Valley. Instead of bucking their timber into 5-foot bolts (2-stave lengths) in the woods, they adopted the practice of taking the full tree length to the plant and recutting with a power cut-off saw into stave lengths. By this method they are reducing their woods cost and also avoiding a large amount of waste of stave wood. The practice is of special

importance where wood-using plants are dependent upon small-size, second-growth logs, and where, no doubt, it could be considerably extended. The accuracy of measuring log lengths in the woods has a direct bearing on the amount of trimming waste produced. If allowance for trimming is greater than necessary, the surplus stock is wasted; while if the logs are cut too short the lumber must be cut down to the next even foot. The use of dull trim saws, and the failure to trim at right angles in the mill and in the woods, are responsible for a great amount of trimming waste. If material has to be retrimmed and remanufactured as the result of poor trimming, an increased cost in skilled labor and a loss in usable material results, which must be charged back directly against the initial cost of manufacture.

SAWDUST. The major quantity of sawdust is produced by the head saws, gang saws, edgers, trimmers, and cut-off saws. The volume of sawdust produced varies with the gage, set, and swage of the saws used and with the size of the material being manufactured. The most obvious method of reducing the quantity of sawdust produced is to use saws with a thinner gage. The thin-gaged saw requires mechanical skill to operate it successfully. There is a tendency in the smaller mills to crowd a thin saw without giving it the proper care, and unless it is filed, hammered, gummed, and run at the right speed it tends to produce miscut lumber. For this reason the thin-gaged saw has not been given an opportunity to prove its value. With correct mechanical care and no abuse, it will produce lumber more efficiently than the thicker-gaged saws, but it must not be forgotten that thin saws can not be operated at the same speed as thicker saws. It is interesting to note from Figure 6 that when a circular saw having a gage of five-sixteenths inch is used in the manufacture of squared timbers into 1-inch lumber approximately 25 per cent of the timber is converted into sawdust; but when a band saw with a gage of seven sixty-fourths inch is used only 10 per cent of the timber is converted into sawdust. The Forest Products Laboratory estimates that the circular head saws waste every year, in excess saw kerf, an amount of wood equivalent to twothirds of a billion cubic feet of standing timber over and above that which would have been wasted had bandsaws been used. Evidently it is impossible to use a fast feed with thin saws. Therefore, reducing the saw kerf may not always be profitable. The operator must decide for himself whether or not the saving which results from the use of a thin saw is justifiable, in the face of the slightly higher labor cost. Many sawyers are careless about changing saws, especially near the end of the day or late in the forenoon. Dull saws produce excessive amounts of sawdust and turn out lumber with an unusually rough surface.

The National Committee on Wood Utilization has given much thought to the introduction of a Scandinavian gang sawing system in the United States. It has sponsored several tests with these saws in this country, and the results have been favorable.

The Scandinavian gang saws differ from the American gang saws in that they are designed for small logs of, say, 15 inches top diameter down to 3 inches in top diameter. They are operated at high speed, the average being 350 revolutions per minute, permitting a log feed of about 20 lineal feet per minute. If the saws are properly filed, the

surface of the cut lumber is so smooth and the material so well manufactured that the sizing process is totally unnecessary; in fact, this lumber is commonly used without further dressing for such purposes as box shooks, where an absolutely smooth surface is not required. There is also saving in saw kerf through the use of thin saws. These gang saws must not be confused with the American type of gang saws, as the latter are designed for the conversion of flitches and square timber of large dimension, while the Scandinavian gang saws are primarily designed for round logs of small dimension; therefore this gang saw supplements the present American sawmill machinery. Its only competitor is the circular saw, which, however, does not cut lumber as well or as accurately as the gang saw. For several years gang saws of this type have been in operation in sawmills in Virginia

FIGURE 7.-Typical Scandinavian type of high-speed sawmill machinery successfully tested by the National Committee on Wood Utilization in various parts of the country. This equip ment is especially designed for sawing small logs which can not be converted into lumber on band saws at a profit

and New Hampshire, and the owners have declared themselves satisfied with the results. Lately the committee has introduced these saws on the Pacific coast.

CARELESS MANUFACTURE.-Careless manufacture is responsible for the production of a large amount of low-grade and nonutilized material. This is especially true as applied to the process of sawing rough lumber. Many mills have a miscut production of 10 to 15 per cent, which could be greatly reduced by efficient sawing equipment, correct carriage alignment, and efficient sawing practice. Carelessness on the part of the sawyer, edgerman, trimmerman, or any of the other operators in the sawmill or planing mill, may produce large quantities of nonutilized material. Careless use of cant hooks, dogs, and tally sticks may cause degrade. If saws are dull or poorly fitted,

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or if the machines are operated at excessive speed, torn grain may result. Poor foundations, carelessness in installation, and negligence in the care of good machinery often cause great waste. In the yard and mill careless handling may cause considerable loss of high-grade lumber by breakage and splits.

In seasoning. The majority of the mechanical defects occurring in lumber, such as checking, splitting, loosening of knots, warping, cupping, honeycombing, etc., are caused in the seasoning process. These defects are responsible for some of the loss and degrade in lumber and are usually called seasoning defects. While it is not practicable to entirely avoid seasoning defects, degrade can be reduced by increased care during the drying process. For example, research has devised a 72-hour kiln-drying schedule for southern pine, which

FIGURE 8.-Edgings utilized for broom-handle squares. Considerable quantities of edging strips, as well as slab materials, can be utilized in the manufacture of small furniture squares, dowelpin stock, turning square material, and other small dimension. The bundles are tied to minimize handling costs

has reduced degrade in the upper-grade drying of that species from 20 to 5 per cent. Degrade in seasoning may also be reduced by good foundations, proper stacking, sanitary conditions, sun protectors to prevent end checking, careful roofing of piles, dipping to prevent stain, modern kilns and equipment, and proper kiln-drying practice. There is an increased tendency among progressive lumber manufacturers to defer the trimming of lumber until after seasoning. This practice eliminates the necessity of trimming ends which have checked in the seasoning process.

By the consumer. The responsibility of the consumer to the lumber industry consists of a proper utilization of the material

For full information regarding sap stains, see bulletin entitled, "Sap Stains of Wood and Their Prevention." Price 35 cents, at Öffice of Superintendent of Documents.