A method of backing carpeting material 19 with hot-melt compositions such as atactic polypropylene (APP) or bitumen (with or without additives) comprises carefully doctoring selected thicknesses of the composition to the undersurface of the material 19 with the wear surface of the material uppermost....http://www.google.com/patents/US4737221?utm_source=gb-gplus-sharePatent US4737221 - Carpet tile production method
