DIY Acid Stained Concrete

This section deals with surface preparation that might be required if your concrete floor has inherent issues that will affect the acid stain process. These techniques are often, but not always, needed for existing concrete floors. Be sure to look at the section on normal floor preparation that is required for stain application.

As was mentioned in other sections, many variables can affect the way acid stains are accepted in concrete. There are four main ways of dealing with problems on the surface of the concrete:

Mechanical abrasion. This is the most aggressive and least desirable technique for solving surface problems. For one thing, the equipment is heavy and expensive; the process is very laborious and the results are not always what you hope. Remember, the acid stain is reacting with the lime that is mostly concentrated in the uppermost ’skim’ of the slab. Abrasion can remove that lime and cause you to have a floor that will not accept stain.

You can, however, use mechanical abrasion to take off high spots or to level out uneven areas. I do not really recommend this method treating an entire floor (but it is an option). Here is an example of a diamond grinder for concrete. These can be found at some rental stores. You can also use hand held grinders with abrasive wheels for small areas.

Overlayment. Using an overlayment product is definitely an option if your slab is in bad shape. This is a very decent option if you have a slab in good structural condition, but with a very poor surface quality. For example, if you uncover a mastic with potential asbestos, use an overlayment. The process for application will not be covered here, but essentially you lay a new concrete floor. In fact, dyes are available for overlayments that then negate the need to acid stain later. These dyes usually produce a monotone color that many people seeking the richness of an acid stain would not appreciate.

Chemical stripping. There are many products on the market that are designed to remove grease, grime, paint, mastic, and whatever else you could apply to concrete. Some are intensely toxic and dangerous (kerosene!) and some are fairly friendly (citrus-based strippers). All of them tend to be expensive and messy!

So none of these options get glowingly positive reviews. That is because they can turn a fun, fairly simple DIY project into a real nightmare. On one project we just completed, there was nasty black paint on the floor and grease everywhere (restaurant, of course). We started with a grinder as seen above. That did not get all of the paint off, but we cleaned it all up and stained over it. Totally awesome! I’ll put some pictures up soon, but it looks kind of rustic and intentional. In the spirit of DIY acid staining, I think you need to be flexible and patient and you might just surprise yourself with the results.

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