Q. I have heard of epoxy flooring contractors "washing" concrete of all contaminants with (correct me if I am wrong) xylem. From what I have been told, it washes the impurities some depth into the concrete where they will not be a factor in failure of adhesion. If there is something out there to “wash” concrete like this other than xylene, I would like to know. We are a soft and hard flooring contractor, and by the time we get to the concrete, it is covered with paint overspray, varnish, pop and coffee spills, oil, grease, and on and on and on. Our flooring material manufacturers require that the substrate is free of all of these impurities, and quite honestly, I believe it is nearly impossible. Do you have any suggestions of where to look for information on this?

A. Unfortunately there is no simple way to prepare a floor for adhesives, special toppings, or coatings. We’ve heard of contractors using xylol or xylene to wipe down areas to remove dirt and lint but not to prepare a floor for flooring, epoxy, or other coatings. We don’t believe there is anything that will push contaminants into the concrete to where they would no longer be an issue. The International Concrete Repair Institute (ICRI) publishes information on preparing concrete surfaces for a wide range of topping treatments. It would be good for you to get a copy of their information. Generally, thicker toppings require more aggressive preparation procedures. We don’t know what finishes or flooring materials you install, but at the least, we would recommend shot-blasting a slab to prepare the surface for the toppings.