Q. My company produces machinery for the textile industry. We pour our own castings. Since they are sand castings, we are spending too much time hand grinding to smooth out the surfaces. Do you have a coating that would be easy to apply and quick drying that would improve the appearance of our castings and eliminate the hand grinding? M.S.
A. Hand finishing of any kind is time consuming. In general, a coating follows the contours of the substrate and telegraphs defects. Thicker coatings minimize these defects. Another alternative that will reduce but not eliminate the hand finishing, is filling with an automotive body putty using a flexible applicator and then sanding. Another is applying a thick coat of primer-surfacer and then sanding. These materials are available from automotive supply stores in conventional and fast drying versions.