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.