The color or texture of old stucco may be changed by resurfacing. If the old stucco is sound and will provide an adequate bond, one coat of new stucco may be applied directly over the existing surface. To do this, the old stucco should first be washed with clear water and then thoroughly cleaned with an acid solution of 1 part muriatic acid and 6 parts water, applied with a stiff bristle brush.
After this treatment, the old surface should be thoroughly rinsed with clear water to remove all traces of the acid, allowed to dry, and moistened again just before applying the new coat.
If the old stucco is unsound, it may be desirable to replace it with a new three-coat job. For this purpose, it is necessary to remove the existing stucco or cover it with waterproof paper and metal reinforcement, applied before the new stucco is put on.
Reinforcement is available with paper backing attached if desired. Portland cement stucco should not be applied directly over lime, gypsum, or magnesite stucco. These surfaces should be refinished with the same kind of material as the original finish unless Portlane cement stucco is desired. The old material should be removed or covered with paper and reinforcement before applying the three new coats.