Durability of Woodworking Glues for Dwellings

This report covers extensive tests made at the Forest Products Laboratory on casein and synthetic resin glues. The suitability of these glues for use in house construction was evaluated. Plywood shear test specimens were obtained from plywood panels made up of three plies of 1/16-inch yellow birch veneer. Original joint quality was determined for each of the eight types of glue used and periodic tests of plywood shear strength were made throughout the test. Tests included exposure of the panels to various cycles of controlled temperature and moisture conditions. Results of the controlled exposures are explained in detail with the use of charts. Another part of the study used 12- by l – by 1/4- or 5/8-inch phenol-bonded Douglas-fir plywood panels bonded to a solid member. These were exposed over a 10-year period, to controlled conditions and these results too are given with the help of charts. Additional plywood panels of yellow birch, yellow poplar, and Douglas-fir along with laminated beams of Douglas-fir, southern yellow pine, and white oak were exposed out-of-doors. Casein glue performed well in all tests when protection from high humidity or direct wetting was afforded. Addition of preservative only retarded destruction of the glue joint. Room-temperature-setting urea-resin glues had greater resistance than casein, but failed in high temperature or high humidity. Rot setting urea resins have better durability than room-temperature-setting ones, but their resistance is not sufficient for long-term permanence. Fortified hot-press urea resin is more durable than straight urea resins, but less durable than phenol, melamine, and resorcinol resins. Phenol-resin glue joints and possibly melamine and resorcinol-resin have the best durability and would be the most suitable for constructions where the glues are required to cure at room temperatures.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member