Abstract: A coating composition particularly useful in sealing and protecting materials used in the construction of buildings and the like is described. This composition comprises a mixture of potassium silicates of varying viscosities catalyzed by a small amount of saturated borax solution. The composition described not only seals and protects the surface and interior of the building materials, but is particularly useful in the treatment of cementitious materials and can further be used to encapsulate and contain any pollutant that may be associated therewith thus rendering the site containing the polluted building materials suitable for habitation.