Selected Answers

From Glenn Summers of Conselcor Inc. on September 17, 2010:
Any contaminant within the gel-pore/capillary ...read more Any contaminant within the gel-pore/capillary system of concrete has the potential to cause a coating failure. I take the approach that all concrete should be sealed from within the matrix prior to any coating operation. Identifying a contaminant type is not as important as is introducing a penetrating sealer to form a solid inside to stabilize the concrete. In the case of animal fats I have noted that, after a steam wash, my sealer will penetrate and expel fat from deep in the matrix up and out to the surface. Another wash to remove expelled contaminants is then followed by another application of the sealer to penetrate and form a solid in the capillary voids. Now I have a stabilized concrete that does not allow an internal chemistry or contaminant to compromise the surface bond of a coating.

From Luis Tapia of CPPQ on September 16, 2010:
Animal or another oil contamination is always ...read more Animal or another oil contamination is always a big problem to coating application over concrete surface. Concrete is porous and absorbs oil. You will know if there is oil on concrete by the water drop test, but I prefer dry methods like UV light. In my experience, a sucessfull way to resolve that problen is scarifying and resurfacing with an epoxy or cementicius grout. Other materials require use of water; and water on concrete will generate other problems because it stays for long time. Eng. Luis Tapia SSPC PSC Jet Flooring Systems CPPQ Peru.

From Jorge Lizarraga of International Paint on September 13, 2010:
Animal fat can be recognized using an ultravi ...read more Animal fat can be recognized using an ultraviolet light. If there is animal fat, we´ll see a blue fluorescence in the surface. We can remove it using a tensioactive in solution with water, and if the tensioctive isn´t enough, treat the surface with alternating washes with solvent(SSPC-SP 1) and tensioactives. I could wash several floors of a gas station, and then paint them succesfully.