n Generally regarded as the blown products of petroleum bitumens, which have been previously obtained as residues from the distillation of crude petroleum. The petroleum bitumens are subjected to high temperature blowing with air, which has profound effects on the properties of the material. Melting point is raised considerably, and the product becomes rubbery. For bitumens of the same melting point, the blown product has a higher penetration figure. See Bitumen and Air Blowing.