What Is Black Mastic?
Mastic is the general term for a type of glue-like flooring adhesive. Many modern mastics are latex, or water-based, and can be softened with water. Asphaltic cutback adhesive is an older type of mastic made with asphalt-based cement. As a petroleum-based material, the cutback is not softened by water. Some cutback adhesives contained asbestos. It is commonly thought that asbestos was added to these compounds for fire-resistance. While this would have a residual effect, the primary purpose of the asbestos was to make the product more durable. Asbestos is a highly fibrous material, and these fibers interlock to help strengthen mastic, insulation, and many other household building products.