Acid Stained Concrete: Should I Resurface Before Staining?

Chemical stains (acid stains) are water based acidic solutions of metallic salts react with the lime in the concrete. After the chemical reaction is completed, the stains (which are actually metallic oxides) become integral part of the concrete and gives it a beautiful mottled colored surface. The critical element of coloring concrete surfaces with an acid stain or chemical stain is the reaction between the stain and lime in the concrete.

In many remodeling projects many people want to rip up their carpets, tile and linoleum and think they can acid stain the existing concrete substrate and achieve a beautiful surface. Unfortunately, it is not that simple. Concrete resurfacing with a self leveling concrete or micro topping becomes necessary in the following cases.

1. Usually under the carpet, tack strips are used to hold down it down and when these tack strips are pulled up after removing the carpet, they create holes in the concrete from the nails used in the tack strips. If the holes are patched and then stained, they will color differently and stick out like a sore thumb. Applying a thin micro-topping over the entire surface hides all imperfections and creates a brand new canvas to acid stain.
2. Sometimes carpets are glued down to the concrete substrate. Even if the carpet glue is removed, there could be some glue residue left in the pores of the concrete which acts as a resist or may create unsightly stains on the surface. It will be a very good idea to cover the entire surface with a thin concrete overlay to get desired results.
3. If the ceramic, porcelain or quarry tiles are in good condition, it behooves to resurface the tiles with self leveling concrete and staining it with a chemical stain. If some tiles are loose or coming off then they should be removed and patched before pouring a self leveling concrete. Removing tiles and grinding of the tile mastic is time consuming, messy and expensive. Be resurfacing the existing tiles, the project can claim LEED points under reduction of waste and pollution in the project.
4. In many metropolitan cities there is a popular trend of converting old warehouses into lofts. Stained concrete is a great look for loft floors. But the existing concrete substrate may not have enough reactive lime for the chemical reaction. In such cases self leveling concrete or micro-topping is the way to go.
5. If the existing concrete surface has paint over spray, permanent ink markings (left by framing contractors), caulk lines, hydraulic oil spills, concrete curing agents and/or fly ash, installing the concrete overlay becomes mandatory for a stained concrete floor.

Please Contact Us to discuss your next stained concrete flooring project.