Method of finishing paper utilizing substrata thermal molding

Claim 1

Process for producing gloss and smoothness on a surface of a paper web independent of the gloss and smoothness produced on the other surface of the web, comprising the steps of: A. providing a finishing apparatus comprising a smooth metal finishing drum and a resilient backing roll pressed against the drum at a force up to 700 KN/M (4000 pounds per lineal inch) to form a nip with pressure against the paper of at least 13,780 KN/M 2 (2000 pounds per square inch) and less than 60,000 KN/M 2 (8,700 pounds per square inch); B. advancing a web of papermaking fibers having a moisture content of from 3% to 7% of the bone dry weight of the fibers through the nip at a speed which results in the web dwelling in the nip from 0.3 milliseconds to 12 milliseconds; and C. simultaneously with step B, heating the drum to a surface temperature which is: (i) higher than Ts-20° C. to thermally mold a substrata of the web beneath said surface; and (ii) lower than that which heats the interior of the web sufficiently deep and sufficiently hot to thermally mold the entire thickness of the web and thereby cause the finishing steps applied to one side of the web to significantly affect the gloss and smoothness characteristics imparted to the other side of the web, wherein Ts is determined by the following formula: Ts=[Ti×0.357t.sup.-0.479 -234.2e.sup.-131m] /[0.357t.sup.-0.479-1] where: Ts=surface temperature of the heated drum, in °C.; Ti=the initial temperature of the web just prior to entering the nip, in °C.; t=dwell time of the web in the nip, in milliseconds; e=the base of the natural logarithm; and m=moisture content of the fibers in the web in weight percent of the bone dry fiber weight.