Cleanliness Verification and Defining Acceptable Cleanliness Levels

Abstract

The key to surface finishing is a ‘properly’ prepared surface. Defining and maintaining the surface preparation at ‘proper’ levels is, at best, subjective. Often the failure of surface preparation processes is not discovered until problems, such as poor adhesion, occur downstream resulting in non-conformance owing to poor quality surface cleanliness. To assure consistent quality of surface cleanliness, it is important to define how clean the surface has to be. This paper discusses the types of contamination, the most common surface cleanliness measuring/verification techniques, factors affecting the choice of cleanliness measuring/verification techniques, and a structured approach to defining the ‘acceptable level of cleanliness’. In short, this paper discusses the ways to define how ‘clean’ is clean.