Abstract: An apparatus and method for forming flat top foam buns or slabs which features positioning solely one sheet of film material to each side of a rising foam body. The single side sheet is positioned in contact with the rising foam on one side and in contact with a rigid side wall on the opposite side. Also, the single side sheet positioned between the rising foam and stationary side wall represents the only material between the side wall and foam material. The side film has a bottom edge which originates below a reference plane lying flush on the bottom supporting surface of the foam bun once it has reached an essentially full rise position. Preferably, bottom and side conveyors are provided near the full rise position of the foam material and the side film is redirected from an upwardly inclined edge arrangement to a horizontal edge arrangement.

Abstract: The present invention relates to a method of producing flexible polyurethane foam having reduced discoloration which utilizes low molecular weight alkanes or mixtures thereof as auxiliary blowing agents. More particularly, the present invention relates to the use of auxiliary blowing agents which are linear or branched alkanes having boiling points above -50.degree. C. and below 100.degree. C.