Stucco can be made from different combinations of material. Traditional stucco is made with only lime, sand and water; modern stuccos can also include cement or glass fibers for added texture. It is often gray, but color is sometimes added by the manufacturer in the finish coat.
The role of sanding in exterior house painting is simple: by removing old paint and sanding down to the wood, you will have an even surface. This ensures that the paint goes on uniformly and adheres to the wood.
Because of the textured nature of stucco houses, it is not advisable to sand down the surface prior to painting. Sanding is not a necessary step since other pre-painting treatments are used instead.
To prepare stucco for painting, wait for a dry spell to ensure that the surface stucco is completely dry. Remove any loose paint flakes and create a smooth, even surface by applying a layer of masonry conditioner to the surface. Exterior latex paint formulated for use on masonry can then be applied, up to two coats. According to Sherwin-Williams, latex paint should have no problem adhering to glass particles in stucco if it has been treated with masonry primer.