To Stick or Not to Stick – Guide to Adhesion Measurement for the Layman

By Dr. Robert H. Lacombe

This two-part article is a condensation of a much larger work1 that deals with the full range of adhesion measurement, including details of continuum theory, frac­ture mechanics, measurement of intrinsic stress, and several detailed applications. It is assumed that most readers are not con­versant with the technical concepts of frac­ture mechanics or continuum theory, so, to establish a baseline of understanding, Part I will provide a brief tutorial on the most relevant aspects of these topics before wading into the main discussion. Part II of the tutorial, to be published in the next issue of Coatings Tech, gives a Consumer Reports-style evaluation of several adhe­sion measurement methods that are of relevance to the coatings industry.

Applying a coating to a surface is a sticky subject and at many times a very slippery one too. The sticky aspect is obvi­ous and needs no further comment. The intent of this tutorial is to give an overview of adhesion measurement as a tool for dealing with the slippery aspects of apply­ing a coating and ensuring that it stays adhered. The essential problem arises from the fact that adhesion is a basic property of surfaces, to quote a famous physicist: “God created matter; surfaces were invented by the devil.”*