Abstract: This foaming system includes a foaming agent solution and a resin solution. The foaming agent includes the relative amounts of 15 to 30 parts by weight of a salt of an alkyl diphenyl oxide sulfonate, 10 to 25 parts of 85% phosphoric acid and 15 to 25 parts urea, all in an aqueous solution. The resin solution includes a resin prepared by reacting 1 to 2.4 mols of formaldehyde per 1 mol of urea, 6.5 to 500 mmols polyethylene glycol as foam charring agent, 0.3 to 1.2 mmols of calcium carbonate as uniform foam cell size agent, 3 to 310 mmols of dicyandiamide as foam hydrolysis resistance agent, 2 to 30 mmols of sodium bromide as foam aging agent, and sufficient water to make a 35 to 45% solution. In preparing the foam, one part by weight of the foaming agent solution of about 5% solids concentration is aerated and then 1.0 to 1.5 parts by weight of the resin solution is sprayed thereon to obtain foam with an average linear shrinkage of about 0.25%.