A. Ron Webber, a veteran plastering contractor in Orange, Calif., responds: I do not recommend using plastic stucco cement — actually a blend of portland cement, silica sand, lime, and fillers to increase plasticity — for patching. It has a high water content and develops a lot of very small shrinkage cracks as it dries, which can cause a patch to break apart prematurely. A better approach is to repair dead hairline cracks — where the stucco is stable and the cracks don’t change size or reappear — by dusting them with premixed, pigmented stucco. I pour dry stucco powder into a cup, then use a dry 1-inch brush to dab the powder into the cracks. Immediately after dusting, I brush any excess off the edges (to prevent buildup) and blend in the patch. Moisture from the night air will help the cement set up overnight.
This technique is quick and easy and gives me a better color match than a wet-mortar repair. Dusting allows me to blend the patch in with the existing texture; simply filling in the cracks tends to leave a telltale “snail trail” of different stucco textures.
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