Q. I want to learn about test methods to check efficiency of degreasing. Do you know anything about a Ford Scotch Tape test? How does it work? How reliable are the results? —B.K.
A. I could not find any information specific to the Ford Scotch Tape test, but there is a well-established test method under the global International Standards Organization (ISO) procedure 8502-3, Preparation of Steel Substrates Before Application of Paints and Related Product—Test for the Assessment of Surface Cleanliness—Part 3: Assessment of Dust on Steel Surfaces Prepared for Painting (Pressure Sensitive Tape Method).
While the title suggests this may only be applicable to steel, in practice it could be used on almost any substrate as a semi-quantitative measure for surface particle cleanliness. It uses a specified tape that is applied to the surface of interest. The tape is removed and examined by comparison to a standard, both visual and descriptive, that classifies the residue on a scale of 0 to 5, with 0 being the best (no particulate visible under 10× magnification). The other classes have a greater density and size of residue. For instance, a rating of 1 describes particulate of no more than 50 microns. At the far end of the spectrum, a rating of 5 describes particulate of greater than 2.5 mm.
This test is only effective for the evaluation of particulate on the surface and would not be applicable to evaluate the removal of organic contaminants, unless the residue was so heavy that it would simply not allow the adhesion of the tape to the substrate. A quick check of the Products Finishing suppliers revealed that there are a few companies that carry kits for this evaluation.