Cleaning either brick or stone requires a sensitive approach and an understanding of the materials and products on the market. Harsh acid based cleaners are commonly used to clean atmospheric carbon off brick and stone. Our soft clay brick combined with a lime (or alkali) mortar stand no chance to high concentrations of hydrofluoric or hydrochloric acid and high pressure. We prefer to use products from Prosoco or Keim and in particular, EK Restoration Cleaner. This cleaner does not contain hydrochloric acid and will not harm soft brick and lime mortar.
We now are working with a hot steam/water system that can remove years of carbon and paint. This does require extensive preparation and waste water containment and proper disposal. Using hot steam and water allows us to use less chemicals which are better for the masonry and environment.