We have a large, covered balcony. The cement pavers our builder left us with and refuses to change, are very badly stained. The entire floor looks dreadful and the builder insists the stains are a "natural condition of cement pavers." We are going to have to stain it this coming Spring and I am wondering what your experience has been with staining this type of material. We have been told we will have to acid wash the surface before we do anything.What kind of stain did you use and what tips can you give us before we start the project.This photo makes the stain look much better than it actually is.