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Using Muriatic Acid for Staining

by Carlos Novela
(Miami, FL USA)

Muriatic Acid

I like to build concrete fountains and decorative steps. Instead of using acid stain to color the surface which is a problem because the concrete is gray and the surface is brown, I like to add iron oxide to white cement mix and use white sand to get a creamy yellow color. I then use muriatic acid to do an acid wash of the surface. So my acid stain is a bit different. The whole goal is to have color inside the concrete slab itself so that when it chips you do not see the ugly gray color.

Using muriatic acid allow me to graduate the intensity of the acid stain and get rid of any rough edge and porosity in the concrete slab. The acid wash prevents uneven fading of color and gives the concrete a smooth glossy feel. I love to create smooth surfaces, not the rough hard surfaces people are used to, To prevent people slipping and falling add small ridges to the surface. These can be created using acid as it eats away at the concrete.

The final result is a project that lasts many years and does not need to be painted since the color is inside the concrete matrix itself.