Blue paint was flaking from motor housings. The paint flakes were examined for artifacts using low power stereo microscopy and high power reflected light microscopy. This was a difficult problem to solve. Careful microscopic exam of paint flakes showed rust particles and Newton rings (generally associated with oil slicks on water, thin films). Further exam showed micro sized oil droplets on the flakes. Drawing fluid used for manufacturing was found to be an aqueous based oil emulsion. This was not washed properly from the parts.