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Ask Concrete Decor: Acid Staining, Powder Release Agents and More

Question (Q) Sometimes when I stamp using a powdered release agent the release will remain too heavy on the surface. Even after power-washing the release off it seems to over-power the base color. How can I take more of the release off to get better accenting with more of the base color showing through?

Answer (A) Sometimes this may happen when you use integral color or pigment. It also happens sometimes when you stamp the concrete too wet or it's cold and damp. You can remove more of the release by adding about one inch of muriatic acid to a five gallon pail of water. Scrub the affected areas with this dilution and then wash with a neutralizing rinse of baking soda or ammonia and water before sealing.

Q I am new to acid staining and would like to know the best floor prep for staining on old and new concrete?

AThe recommended floor preparation for staining is sanding. This can be done with a sanding disc on a floor scrubber. Edges can be done with a grinder and sanding disc attachment. Rough spots and hardened mastic on tile grout can be removed with carborundum discs or diamond discs. Always use silicon carbide or diamond discs when sanding concrete.

Q If I have removed too much release agent or I have an old stamp job I want to add more release agent color accent to, can it be done?

A You can add more release color accenting by mixing the release powder with a solvent such as acetone and washing this on the areas with a rag. Then take another solvent dampened rag and rub off the excess, leaving the color in the low textured areas (“wax on – wax off”). Then seal when dry with a good solvent sealer.

Q How long do you have to wait to acid stain new concrete and what colors are available?

AIt is recommended to wait 28 days to let the concrete fully cure before acid staining. This is especially critical when using blue - green colors. Acid stains are available in what are called “earth-tones” only. These are tan to light brown, reddish brown to dark brown, black, green and some blue/greens.

QWill the stain look different if you use a water-based sealer or a solvent based sealer?

A A water based sealer will help to retain the soft colors and pastels while a solvent based sealer will darken the hues and give a deeper richer look. If you can, you may want to test and do samples of both so you may show or explain the difference to your customer.

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