In preceding blogs we have talked about harvesting particles for evaluation and talked about specifications.  Specifications may or may not dictate the harvesting process but almost always provide detail on how to evaluate the particles harvested in a process involving re-washing.  The first step is to concentrate the harvested particles for evaluation.  This usually involves a filtration and evaporation process.  …

The evaluation of cleanliness is often based on a quantification of the particles left on a surface following the conventional or production cleaning process.  The first step in evaluating a part for cleanliness with regard to particles is to harvest those particles that remain after cleaning.  Once harvested, the particles can be counted, weighed, microscopically …

So far in this series we have concentrated primarily on the detection of oil and other hydrophobic films on surfaces.  However, not all contaminating films are oil and all are not hydrophobic.  What about contaminants that are not hydrophobic and may even by hydrophilic (residual soaps and surfactants, for example) as well as things like oxides?  These are just …

The tests described in the last couple of blogs are rudimentary ways to assess the surface activity of the surface being tested.  In fact, they are all based on the concept of contact angle.  A drop of water resting at equilibrium on a surface will intersect that surface at a measurable angle called the contact angle.  The …