Age Before Beauty

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Q: Over time, stucco picks up particulates that add texture to the rough surface. When my architect designed a compatible addition to my stuccoed 1924 Country Italian villa, we found it impossible to match its 70-year-old characteristics. Do you know of a technique to successfully ÒageÓ new stucco?A: The best way to artificially age new stucco is to lightly mist the final coat with water before it sets up, according to specialists in historic masonry. Some of the surface lime (the ÒcreamÓ between the particles) will wash away, giving the texture a weathered look. Or allow the stucco to cure overnight; then mist it with water, and brush away some of the surface lime with a soft, nylon bristle brush. For fully cured new stucco, try a muriatic acid bath. While this method wonÕt harm the stucco if used correctly, some precautions are in order. Muriatic acid is a powerful solution commonly used in masonry cleanup. It can damage woodwork and painted surfaces. Also, the stucco must be thoroughly soaked with water before the acid is applied; otherwise, the acid will be absorbed too quickly and could damage the substrate. Use a ratio of 1 part muriatic acid to 4 or 5 parts water. Because this solution can severely burn skin, wear protective clothing, including rubber gloves, a long-sleeved shirt, and protective glasses. You may want to test the strength of the bath on an out-of-the-way part of the building before proceeding. Apply the acid bath with a long-handled bristle brush, beginning at the top of each wall, and broadcast the wash around. The surface should begin to bubble, indicating that the acid is wearing the lime away and exposing more of the sand in the finish. This will affect the way light is reflected off the surface, resulting in an older-looking appearance.

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