Abstract
EXPERIMENTS carried out at the Forest Research Institute, DehraDun, indicate that compregnated wood which compares favourably with foreign samples (tests on a foreign specimen of compregnated birch are given) can be produced from Indian timbers. In Indian Forest Leaflet No. 77—1945 (Utilization) entitled "Preliminary Studies on Improved Wood, Part III. Compregnated Wood" (published by Forest Research Institute, Dehra Dun, 1945), it is stated that wood of highly improved properties can be obtained by a suitable combination of impregnation, lamination and compression. In the case of compressed wood and lignostone, whole wood scantlings are used and, by application of great compression, the properties of the material are made uniform in the main direction. In the case of compregnated wood, the timber is sub-divided into veneers, and impregnated with resins, or thin films of glue are placed between the veneers; finally the pack is compressed at a high pressure at a suitable temperature. Alcoholic solutions of resin or film glues, such as Tego film, etc., are used. It is said that by suitable choice of the species of wood, thickness of the veneers, pressure and temperature employed, and the direction of laying the veneers, the properties of the resulting material can be varied to meet particular requirements. The uses of this material, it is held, are very varied—aeroplane propeller blades are given as an example. The main defects of natural wood in this connexion are low hardness; low cleavage strength; low shear strength and great hygroscopicity. Compregnated wood, on the other hand, has high tensile strength; high shear strength to cope with the high centrifugal stresses at the boss, which at the same time are reduced to a minimum due to the low density of the material in contrast to metal; high damping capacity; favourable strength density ratio; lightness (weight of such blades are a third of metal ones); increases in efficiency (about 6 per cent) by the use of such blades; ease of repair; and finally, it is claimed, freedom from tiring, which is so frequently the cause of fatal air accidents in aeroplanes fitted with metal propellers. Other uses are gear wheels, bearings (ships' tail shafts, rolling mills, textile mills, etc.), fish plates, press forms, gun stocks, electrical machinery and so forth.
Article PDF
Rights and permissions
About this article
Cite this article
Studies on Compregnated Wood. Nature 156, 787–788 (1945). https://doi.org/10.1038/156787b0
Issue Date:
DOI: https://doi.org/10.1038/156787b0