Status of Wood Drying, 1959

Industrial progress on preseasoning treatments, air-drying, kiln-drying, and applied and fundamental research are discussed under the following headings. Preseasoning treatments.–The prevention and control of brown stain during drying of sugar pine and white pine were developed by the Western Pine Association. It consists of a dip in sodium azide. Wax emulsion end coatings are being used effectively on redwood timbers prior to air-drying. The use of Lumber Cure or salt is giving trouble in electronic gluing and in other uses in humid locations. Air-drying.–Wider pile spacing, and better grading and surfacing of drying yards are being practiced and finding favor from British Columbia to the Deep South. Roofing of the seasoning yard or a major part of it is gaining in the Southeast. Accelerated air-drying by means of forced-air circulation has expanded considerably and is being used for both pine and hardwoods. The process when properly used reduces degrade and reduces final kiln time. Commercial application is proceeding rapidly. Kiln-drying.–Great expansions are going on with wide spread improvements in equipment, methods, and reductions in operating costs being noticed. Gas-fired kilns are coming on fast in the South. Custom dry-kiln firms have matured especially in the East. The Canadians have been very active in the high temperature aspects of kiln-drying, and the Ottawa Laboratory has published a report including time schedules for some eastern Canadian softwoods. Special drying methods.–The vapor-drying process using hydrophobic xylene continues to expand. Dry lumber shipment and storage.–The use of coverings or wrappings on dried lumber is increasing all over the country. The added cost is easily offset by reduced losses. Paper wrapping of small quantities of the higher grades of lumber seems to be gaining favor. Applied research.–Smith tested dried California black oak and found that predrying to 20 percent moisture content before kiln-drying resulted in less degrade than higher moisture levels. Roof covers for lumber piles were found to pay off for oak. Page found in his Georgia study of stacking methods for yellow pine that there was little difference in drying time or degrade except that seven more days were required to reach 18 percent moisture content for the flat piles. A bibliography of 105 references is included.

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