Clear Epoxy Sealers

I had an enquiry today concerning overcoating a previously sealed cement floor with a twin pack epoxy. The client was not satisfied with an alkyd based sealer previously used and asked a contractor to apply a twin pack epoxy clear coat over the existing coating. The contractor went ahead and the alkyd based coating dissolved causing the epoxy to peel off in large areas. When using a twin pack epoxy or polyurethane over previously coated surfaces, it is essential to determine the compatibility of the two systems. In this case the solvents in the epoxy coating re-dissolved the underlying layer causing the observed failure. The alkyd-based sealer should have been completely removed prior to use of the twin pack coating. Fortunately this was a small area in a domestic home and the client felt partially responsible!!