Thompsons Water Seal, provides a clear long lasting waterproof seal, stops moisture, water or damp penetrating your exterior walls. Silicone micro emulsion is breathable and provides excellent protection for brick-work, aged concrete, render, slate, painting, terracotta and wood, exterior use only. This product can be used on all properties, including old buildings and renovated cottages, and almost all surfaces, except limestone and plywood. It is especially ideal for exposed and porous walls that take the worst of the weather. Apply with a good external brush or roller. Approximate coverage, 5 litres covers about 10m² in two coats, drys in about 2 hours.