Mastic Coatings are composed of a proportioned mixture of asphalt, sand, lime dust and asbestos fibres. Mastic coatings are designed both for corrosion mitigation and for weighting pipe laid in swamps or under water. The mastic coatings are usually 30-50 wet mils thick and considerably thicker than those applied with conventional paint. Mastic coating provide a vapor-retarding action and are applied like paint.