Abstract
After describing briefly the production of plywood by hot-gluing from undried and dried veneers, the paper narrates the progress made in the last 15 years by European plywood manufacturers. This advance, says the author, is the result of the publication of articles in the technical and trade journals, cooperative research by press and glue manufacturers, shortage of raw material, and development of new bonding processes that required greater accuracy. Resin films are credited with improvements that have been made in equipment and accuracy of working. Column-type presses have been replaced by the so-called compensated or side-plate machines which can be guaranteed not to exceed a maximum deflection under full load of 0.0015 in. Heating of presses by steam has been replaced with hot water under high pressure, and an electric heating plate that was developed in 1925 is described. New applications of plywood to the production of tennis-racket frames, barrels, structural shapes, and straight blocks or curved material having from 45 to over 70 plies are commented upon briefly. Restrictions upon importation of certain hardwoods into some countries has led to development of multilaminated substitutes, which would not have been possible, in the author’s opinion, without the progress that has been made in hot-gluing. Development of cold-setting resin glues in the last four years is also commented upon, the point being stressed that different manufacturing methods and equipment must be used before the process will offer serious competition.
