Duplicating master sheets

Claim 1

THE METHOD OF PRODUCING A HECTOGRAPHIC SPIRIT DUPLICATING MASTER OR LIKE SHEET FROM A SHEET BEARING AN ORIGINAL IMAGE IN MATERIAL NON-ABSORPTIVE OF INFRA-RED RADIATION, WHICH COMPRISES THE STEPS OF PROVIDING AN OFFSET REPEAT OF THE ORIGINAL IMAGE IN HEAT SENSITIVE PIGMENTCONTAINING MATERIAL WHICH IS ABSORPTIVE OF INFRA-RED RADIATION ON THE SIDE OF SAID ORIGINAL SHEET OPPOSITE TO THAT CARRYING THE ORIGINAL IMAGE, PLACING A RECEPTIVE SHEET OF MATERIAL SUITABLE FOR FORMING THE BASE OF THE PRODUCED MASTER SHEET BETWEEN THE IMAGE-BEARING ORIGINAL SHEET AND A TRANSFER SHEET OF HEAT SENSITIVE TRANSFER MATERIAL INCLUDING AN ALCOHOL-SOLUBLE PIGMENT, THE SIDE OF SAID ORIGINAL SHEET CARRYING SAID OFF-SET REPEAT OF THE ORIGINAL IMAGE BEING IN CONTACT WITH ONE SIDE OF SAID RECEPTIVE SHEET AND THE HEAT SENSITIVE TRANSFER MATERIAL OF SAID TRANSFER SHEET BEING IN CONTACT WITH THE OPPOSITE SIDE OF SAID RECEPTIVE SHEET, MAINTAINING SAID SHEETS IN FACE-TO-FACE CONTACT WITH ONE ANOTHER WHILE SUBJECTING THEM TO INFRA-RED RADIATION OF AN AMOUNT SUFFICIENT TO CAUSE MELTING AND DISPLACEMENT OF SAID OFF-SET IMAGE MATERIAL AND SAID TRANSFER MATERIAL TO OPPOSITE SIDES OF SAID RECEPTIVE SHEET BY HEAT FROM SAID OFF-SET REPEAT OF THE ORIGINAL IMAGE UPON HEATING OF SUCH OFF-SET REPEAT IMAGE BY ABSORPTION OF SAID RADIATION AND THEN REMOVING SAID RECEPTIVE SHEET FOR USE AS THE REQUIRED DUPLICATING MASTER SHEET.