Methods of preparing mastic sheet material

Claim 1

A METHOD OF TREATING A BITUMINOUS MASTIC SHEET OF EXTENSIVE DIMENSIONS, WHICH METHOD COMPRISES SUBMERGING A LAYER OF FILLER-AND-FIBER-CONTAINING BITUMINOUS MASTIC CONTAINING HEAT-LIQUEFIABLE BITUMEN, IN LIQUEFIED COALDIGESTION PITCH RESISTANT TO FLOW AT HIGH ATMOSPHERIC TEMPERATURES AND NON-BRITTLE AT LOW ATMOSPHERIC TEMPERATURES, THE SAID MASTIC LAYER BEING NORMALLY SUBJECT TO CHANGE OF SHAPE WHILE SUBMERGED IN SAID LIQUEFIED PITCH, AND RAISING THE SAID LAYER SUBSTANTIALLY VERTICALLY IN THE BODY OF SAID LIQUEFIED PITCH AT A DECELERATING RATE WHILE UNIFORMLY SURFACING THE SAID LAYER BUT PREVENTING DURING SUBMERGENCE ANY SUBSTANTIALLY DIFFERENT CHANGE IN PHYSICAL SHAPE OF ANY PORTION OF SAID LAYER, THEREBY OBTAINING A MASTIC SHEET HAVING IN ITS SERVICE-EXPOSED SURFACES A UNIFORMLY HIGH CONCENTRATION OF SAID COAL-DIGESTION PITCH FOR RESISTING PLASTIC FLOW, AND SURFACE-CRACKING IN SAID LAYER ON SUDDEN BENDING OR FROM MECHANICAL SHOCK.