Sealers for Underwater Exposure

By Chris Sullivan – ChemSystems, Inc.

Question:

We are installing a concrete garden fountain, and I plan to stain it myself. What are the best stain and sealer products for this type of project, and what maintenance is required?

Answer:

I am not a fan of stain and sealer on surfaces that are often wet or come in continuous contact with water. Unless you use a sealer designed specifically for constant water contact, you will have performance issues like haze and whitening and eventual failure. Sealers that can handle constant water contact are usually high-end epoxies, polyurethanes and polyureas. Before using one of these products, make sure it's designed to be used in conjunction with a stain or tint.

We have seen concrete in continuously wet or underwater conditions colored successfully with just an acid stain or UV-stable tint or dye, with no sealer. If you go this route, make sure to use a product that is not water-soluble. Otherwise, the water will leach out the color over time, leaving you with plain gray concrete.

No matter what route you take, annual maintenance will probably be needed. This will include resealing (if you use a sealer) or at least removing white mineral deposits left on the concrete from hard water. A standard over-the-counter household bath scum and mineral remover works well in this situation.

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