Abstract: The present invention relates to a method of forming a solar collector, or absorber, panels or a heat storage tank, suitable for heating water using solar energy. It also relates to articles of manufacture so formed and to solar water heating apparatus using said articles. Three methods of forming the panel or tank from two sheets of uncured elastic material, such as EPDM rubber, by simultaneously bonding and curing such material around the peripheral edges of the two sheets and at spaced apart, discrete areas over most of the interior areas of the sheets. In one form of the method, one of the sheets is coated with a layer of release agent, over all areas except the discrete areas and the peripheral areas so that only such uncoated areas will bond during cure. In another form, a sheet of non-adherent plastic slightly smaller than the two sheets and having holes or holidays to form the discrete areas is bonded between the two sheets.

Abstract: Thin flexible urethane foam film layers are produced by spreading a layer of polyurethane reactants over a carrier sheet at a uniform layer thickness. The polyurethane reactants consist essentially of an isocyanate and a hydroxyl terminated polyol having an inorganic carbon dioxide producing blowing agent incorporated therein and being free of water. The unconfined film layer is then heated to a temperature in the range of from 260.degree.F to 390.degree.F to cause gellation and release of the carbon dioxide in the mixture with final formation of a uniform thickness flexible polyurethane foam product.