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Acid Staining Concrete Previously Covered with Vinyl, Ceramic or Laminate Tile

Question:

I recently ground, cleaned and acid stained by basement floor. Even after hours of surface preparation, I still see tile ghosting even after I completely removed them from the floor. Why has this happened and what can be done to fix the problem?

Explanation:

Stick on tile is commonly used on interior floors, especially basements and older floors. Tile is often left on the concrete for many, many years. The uneven pressure applied to the tile over the years by walking, furniture and life in general presses the square shape of the tile into the concrete leaving tile ghosting or a deep alternation of the surface behind. Unfortunately, the impressions can’t always be seen prior to acid staining and can still be present even after grinding the concrete. Because acid stain is a chemically-reactive colorant, it will pool in the lower lying areas and appear comparably darker than the rest of the floor.

Solution:

The floor still needs to be ground and properly cleaned before staining. Carefully determine if any aggregate or sand particles have been revealed in the grinding process before deciding on a staining product. Acid stain can still be used but it will not color stones or sand visible in the surface. Most customers will acid stain the concrete then use a topical stain to touch up areas that don’t take the stain well or where the tile matrix is can be seen. Liquid Colored Antique Concrete Stain is a great option to blend the colors in on more porous floors. DCI Concrete Dye can also be used to cover imperfections and accent the floor as needed.

Topical stains can disguise the tile ghosting still visible after grinding. One or more Liquid Colored Antique colors can be used alone after grinding if desired but the finished look will have a more solid, less diffuse look when compared to acid stained floors. A combination of Tinted Concrete Sealer and DCI Concrete Dye is also a good alternative if the floor cannot be successfully acid stained after grinding due to significant exposed aggregate and sand.

Unless you have excellent ventilation to the outside, water based sealers, like the Krystal Kote High Gloss and DCI Water Based Satin Gloss, are best for use on interior projects. Follow with a Concrete Wax product as the final protective coat.

Send us a message or comment on this post with your project woes and we’ll help you with a solution. Find more Q & A posts on challenging decorative concrete topics in our Design Blog.