Putting Wood Waste To Work
( Originally Published 1922 )
For many years technical studies of wood were neglected. Detailed investigations of steel, concrete, oil, rubber and other materials were made but wood apparently was forgotten. It has been only during the last decade since the establishment of the Forest Products Laboratory of the United States Forest Service, at Madison, Wisconsin, that tests and experiments to determine the real value of different woods have been begun. One of the big problems of the government scientists at that station, which is conducted in cooperation with the University of Wisconsin, is to check the needless waste of wood. By actual test they find out all about the wasteful practices of lumbering in the woods and mills. Then they try to educate and convert the lumbermen and manufacturers away from such practices.
The laboratory experts have already performed more than 500,000 tests with 149 different kinds of native woods. As a result of these experiments, these woods are now being used to better advantage with less waste in the building and manufacturing industries. A potential saving of at least 20 per cent. of the timbers used for building purposes is promised, which means a salvage of about $40,000,000 annually as a result of strength tests of southern yellow pine and Douglas fir. Additional tests have shown that ' the red heartwood of hickory is just as strong and serviceable as the white sapwood. Formerly, the custom has been to throw away the heart-wood as useless. This discovery greatly extends the use of our hickory supply.
Heretofore, the custom has been to season woods by drying them in the sun. This method of curing not only took a long time but also was wasteful and expensive. The forestry scientists and lumbermen have now improved the use of dry kilns and artificial systems of curing green lumber. Now more than thirty-five of the leading woods such as Douglas fir, southern yellow pine, spruce, gum and oak can be seasoned in the kilns in short time. It used-to take about two years of air drying to season fir and spruce. At present the artificial kiln performs this job in from twenty to forty days. The kiln-dried lumber is just as strong and useful for construction as the air-cured stock. Tests have proved that kiln drying of walnut for use in gun stocks or airplane propellers, in some cases reduced the waste of material from 60 to 2 per cent. The kiln-dried material was ready for use in one-third the time it would have taken to season the material in the air. Heavy green oak timbers for wagons and wheels were dried in the kiln in ninety to one hundred days. It would have taken two years to cure this material outdoors.
By their valuable test work, scientists are devising efficient means of protecting wood against decay. They treat the woods with such chemicals as creosote, zinc chloride and other preservatives. The life of the average railroad tie is at least doubled by such treatment. We could save about one and one-half billion board feet of valuable hardwood lumber annually if all the 85,000,000 untreated railroad ties now in use could be protected in this manner. If all wood exposed to decay were similarly treated, we could save about six billion board feet of timber each year.
About one-sixth of all the lumber that is cut in the United States is used in making crates and packing boxes. The majority of these boxes are not satisfactory. Either they are not strong enough or else they are not the right size or shape. During a recent year, the railroads paid out more than $100,000,000 to shippers who lost goods in transit due to boxes and crates that were damaged in shipment.
In order to find out what woods are best to use in crates and boxes and what sizes and shapes will withstand rough handling, the Laboratory experts developed a novel drum that tosses the boxes to and fro and gives them the same kind of rough handling they get on the railroad. This testing machine has demonstrated that the proper method of nailing the box is of great importance. Tests have shown that the weakest wood properly nailed into a container is more serviceable than the strongest wood poorly nailed. Better designs of boxes have been worked out which save lumber and space and produce stronger containers.
Educating the lumbering industry away from extravagant practices is one of the important activities of the modern forestry experts. Operators who manufacture handles, spokes, chairs, furniture, toys and agricultural implements could, by scientific methods of wood using, pro-duce just as good products by using 10 to 50 per cent. of the tree as they do by using all of it. The furniture industry not infrequently wastes from 40 to 60 per cent. of the raw lumber which it buys. Much of this waste could be saved by cutting the small sizes of material directly from the log instead of from lumber. It is also essential that sizes of material used in these industries be standardized.
The Forest Products Laboratory has perfected practical methods of building up material from small pieces which otherwise would be thrown away. For example, shoe lasts, hat blocks, bowling pins, base-ball bats, wagon bolsters and wheel hubs are now made of short pieces of material which are fastened together with waterproof glue. If this method of built-up construction can be made popular in all sections of the country, very great savings in our annual consumption of wood can be brought about. As matters now stand, approximately 25 per cent. of the tree in the forest is lost or wasted in the woods, 40 per cent. at the mills, 5 per cent. in seasoning the lumber and from 5 to 10 per cent. in working the lumber over into the manufactured articles. This new method of construction which makes full use of odds and ends and slabs and edgings offers a profitable way to make use of the 75 per cent. of material which now is wasted.
The vast importance of preserving our forests is emphasized when one stops to consider the great number of uses to which wood is put. In addition to being used as a building material, wood is also manufactured into newspaper and writing paper. Furthermore, it is a most important product in the making of linoleum, artificial silk, gunpowder, paints, soaps, inks, celluloid, varnishes, sausage casings, chloroform and iodoform. Wood alcohol, which is made by the destructive distillation of wood, is another important by product. Acetate of lime, which is used extensively in chemical plants, and charcoal, are other products which result from wood distillation. The charcoal makes a good fuel and is valuable for smelting iron, tin and copper, in the manufacture of gunpowder, as an insulating material, and as a clarifier in sugar refineries.
It is predicted that the future fuel for use in automobile engines will be obtained from wood waste. Ethyl or "grain" alcohol can now be made from sawdust and other mill refuse. One ton of dry Douglas fir or southern yellow pine will yield from twenty to twenty-five gallons of 95 per cent. alcohol. It is estimated that more than 300,000,000 gallons of alcohol could be made annually from wood now wasted at the mills. This supply could be increased by the use of second growth, inferior trees and other low-grade material.