Abstract: This invention relates to an improvement in the art of making high pressure laminated materials utilizing kraft paper. More particularly, the invention relates to an improved method of releasing from one another in a press pack a plurality of heat and pressure consolidated resin impregnated laminates, which method comprises utilizing, as a release sheet, a cellulosic-based paper substrate to which an aqueous solution of water-soluble multivalent salt (or salts) is applied during formation of the substrate, and wherein the substrate is subsequently coated after formation on at least one side salt-treated side with a film of a salt of alginic acid.