Compatibility of Water- and Solvent-Based Sealers

By Chris Sullivan – ChemSystems, Inc.

Question:

I had a stamped concrete patio poured last July. The contractor sealed it with a water-based acrylic sealer. It seems from what I have read on The Concrete Network that a solvent-based product might have been better. Can I go back now and seal over the existing water-based sealer with a solvent-based sealer?

Water-based sealers typically provide a matte to satin level of gloss.
Do not seal over them with a solvent-based product.

Answer:

In general, putting a solvent-based sealer on top of a water-based sealer is a bad idea. The solvents can eat or soften the existing water-based sealer, destroying both coatings. Think of it along the lines of oil and water; they do not mix.

There is nothing wrong with water-based sealers. They tend to have low gloss levels (matte to stain) and do not darken the surface as much solvent-based sealers do. I suggest that you perform a scratch test to see how well the sealer is adhering to the concrete. (See How to Test Sealers for Adhesion). If you have good adhesion, you can reseal with the same water-based system when the time comes. If you do want to switch to a solvent-based sealer, you will need to chemically strip off the existing water-based sealer before applying the solvent-based product.

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