SMARTCOAT™ 350 Silicone Mastic is a professional grade high performing silicone mastic intended to seal leaking seams, fasteners, penetrations and/or any splits, tears or deficiencies in the roof's surface prior to coating with SMARTCOAT 450 High Solids Silicone Coating. This product is suitable for application to metal, asphalt, modified bitumen, concrete and most single-ply roofs. Upon cure, SMARTCOAT 350 forms a durable, breathable and water-resistant barrier that is resistant to degradation from UV and natural weathering; coating is not required.