Investigation of Sanded Acrylic Surfaces by Optical Microscopy

Sanded acrylic surfaces have been examined with optical microscopy for evidence of grit embedded by the sanding process. The number of surface imperfections (pits or particles) larger than 5 microns was a factor of two to three times larger in the sanded surface than on a surface that had not been sanded. It was usually possible to distinguish an empty pit from a foreign particle, and the analysis indicated that the larger number of imperfections on the sanded surface was associated with the presence of foreign matter, presumably particles of grit from the sanding. Estimates of the radioactivity that might be associated with such particles are made under various assumptions.