The Testing of Adhesives for Timber

Abstract

Mr. Douglas : From very early days adhesives have played an important part in the joiners’ trade. The necessity for consistent high quality in glues and cements became acute when they were used under conditions of high stress in aircraft structures. It is natural, therefore, to find that aeronautical interests have been largely represented on research committees which have investigated the use of adhesives. At the end of 1919 the Adhesives Research Committee of the Department of Scientific and Industrial Research was formed to continue the work of the Adhesives Committee of the Conjoint Board of Scientific Societies. It was realised that one of the obstacles to the study of adhesives was the unsatisfactory nature of the tests which determine their strength in timber joints. Many properties of glue (such as viscosity, jelly strength, etc.) have been used to control variation during manufacture or as an indication of probable relative strengths in timber joints, but it has never been generallyadmitted that any simple property of the glue itself can be accepted as representative of the ability of that glue to effect a joint with timber. In the present state of our knowledge, therefore, it appears to be necessary to make final appeal to the timber glue test piece.