Method of making soft and drapeable foamed plastic sheeting

Claim 1

THAT METHOD OF PREPARING, FROM FULLY CURED, COMMERCIAL POLYURETHANE SHEET FOAM, A SOFT, ELASTICALLY STRETCHABLE, HOMOGENEOUS, SINGLE PLY, POROUS SHEET WHICH IS PERVIOUS TO AIR AND WATER AND WHICH IS OF CELLULAR STRUCTURE THROUGHOUT AND HAVING THEREIN ISOLATED DEPRESSIONS IN EACH OF ITS FACES, THE DEPRESSIONS BEING OF APPROXIMATELY THE SAME SHAPE AND SIZE AND BEING DISPOSED IN ROWS, WHEREIN THOSE IN ONE ROW ARE STAGGERED RELATIVELY TO THOSE IN ADJACENT ROWS, AND WHEREIN EACH DEPRESSION IN ONE FACE IS DIRECTLY OPPOSITE TO AND REGISTERS WITH A DEPRESSION IN THE OTHER FACE, SAID METHOD COMPRISING AS STEPS: PROVIDING A SHEET OF COMMERCIAL, FULLY CURED POLYURETHANE FOAM OF SELECTED THICKNESS, SUPPORTING SAID SHEET UPON A SMOOTH SURFACED RIGID BED MEMBER, APPLYING TENSIONING STRESS TO THE SHEET SUCH AS TO ELONGATE IT, AND, WHILE MAINTAINING SAID TENSIONING STRESS, SO PRESSING SUITABLY SHAPED HEATED INDENTING ELEMENTS DOWNWARDLY INTO THETENSIONED SHEET THAT, AS THE RESULT OF SUCH PRESSURE, THERE IS FORMED IN EACH FACE OF THE SHEET AN ALL-OVER SURFACE PATTERN OF ISOLATED INDENTATIONS OF SUCH DEPTH AND SO ARRANGED AS TO BREAK THE CONTINUITY OF EACH SURFACE OF THE SHEET AND TO DEFINE RELATIVELY MOVABLE MASSES OF FOAM MATERIAL INTEGRALLY JOINED BY THIN WEBS OF THE FOAM MATERIAL, AND MAINTAINING SAID HEATED ELEMENTS AT A TEMPERATURE SUCH AS TO IMPART A PERMANENT SHAPE TO SAID MASSES AND WEBS BUT WITHOUT MELTING OR DAMAGING ANY OF THE POLYURETHANE SHEET MATERIAL.