Pen-E-Guard will maintain the un-sealed look, whilst protecting the surface from water and staining. Pen-E-Guard is fast curing water based sealer and can be used indoors or outdoors, with no unpleasant odours or flammability problems. Designed to protect concrete, terracotta, unglazed tiles, pavers, sandstone and other natural rock against water damage and staining. Provides superior stain resistance properties against contaminants such as oil, grease, tea and coffee. Minimises the occurrence of efflorescence and reduces dust, moss, mould and algae. Resistant to chemicals, solvents, acid and alkali. Pen-E-Guard will last up to 10 years or longer dependant on application and weather conditions and quality and abuse of the surface.