Other sources of stucco stains, ranging from mold, soot and paint to vining plants, grasses and shrubs, can be removed with one or a combination of several methods:
- chemically -- with specialized cleaning agents for stone, lime, cement and stucco or with diluted bleach (if tolerated in a sample test of the area to be cleaned)
- with water pressure -- using even spraying with a home garden hose and attachment or with a higher-pressure spray system
- mechanically -- with brushes and sandpaper or other abrasives and muscle power, detergents and sponges
Whether using a wet or dry method, stucco cleaning should most often be a gentle process. Saturating or pre-wetting stained areas with water will help to draw stains to the surface, and once the pores are full and discoloration is closer to the top, removing problem areas usually won't involve getting rough with the stucco and damaging the surface.
Other than being careful not to rough up or compromise the outer stucco layers and designs, another concern is protecting the ground around the wall or spot being cleaned so chemicals and particles of lime, concrete or acrylics don't flow into the soil and drainage areas.
If approaching clean-up of historic stucco with the added wear-and-tear of age, it also may be best to consult a professional building restoration consultant or preservationist before getting started.
Whatever the stucco stain, you don't have to be stuck living with it.