Q & A: Acid Staining Rough and Textured Concrete Floors
How does exposed aggregate or other surface imperfections affect my acid stained concrete floor outcome? Is there anything I can do to improve the appearance of the floor if I don’t like it?
Exposed aggregate as displayed in the stained concrete image below does typically stain lighter than the rest of the floor. Aggregate is often exposed when grinding or brushing machines are used to remove surface contaminants during the floor prep process. Depending on the quality of the concrete floor, sand and/or small stones can be unintentionally revealed leading to a rough or highly textured surface. It’s not the end of the world when this happens but acid stain cannot chemically react with stones or sand so the color will be less apparent in those areas.
While aggregate has been revealed on this concrete floor, the areas are not widespread and the stain has taken to some degree. If larger sand particles or stones are present with little cement around them, the outcome will likely be less favorable. In that case, consider touching up the areas using either a tinted concrete sealer or a liquid colored antique concrete stain. Depending on your needs, either will blend the discoloration in with rest of the floor. Liquid Colored Antique is a great choice for more porous concrete floors where multiple colors might be needed for blending. Tinted Sealer works best on single acid stain colors where match can be more easily obtained.
If “whirl” marks are present on the concrete after profiling, they will be more not less pronounced after sealing. We recommend sanding the floor prior to acid staining with successive grit pads beginning with 80 grit and finishing with 200 grit to minimize the their appearance.