Failures of polymerized epoxy coatings applied over latex/acrylic block fillers continue to plague owners of commercial buildings, particularly those with high architectural content such as condominiums, high rise offices, etc. Water treatment facilities in paper mills are especially prone to this problem. The types of failures include delamination of the topcoats, blisters in both the block fillers aud the topcoats and disintegration of the block filler itself. While the problem is welf known, the appreach to a solution is not. A study of several coaings manufacturer’s Product Data Sheets shows a wide variance in the recommendations for what are purportedly generically equivalent block fillers. While one manufacturer might take an essentially architectural approach, another will take a heavy-duty industrial approach. To the specifying architect or engineer who has little training in the complexities of protective coating systems, this presents a dilemma. Who does he believe? What does he specify? To whom can he turn for independent advice? Keywords: block filler, concrete surfacers, epoxy topcoats, latex, acrylic, polyvinyl acetate, vinyl acrylic , cementitious, alkyd, polyamide epoxy, polyamine epoxy, epoxy ester, aliphatic polyurethane, aromatic polyurethane.