Abstract: Laminated heater plate assembly is formed from a plurality of layers of glass cloth and/or glass mat and epoxy resin which are laminated together under heat and pressure. One or more thermally conductive heater members are mounted in a cut-out region(s) in a pre-cured or "C" stage laminate top portion of the assembly while a plurality of uncured or "B" stage glass mat and epoxy resin laminations are stacked, assembled under the "C" stage portion and heater portion(s), and bonded to each other into a rigid, warp-free heater plate assembly which can be repeatedly subjected to steam or hot water without damage. Preferably, the resin density after bonding in the region of the edges of the heater portion(s) and the adjacent surrounding edges of the cut-out region(s) is greater than in locations spaced further from the heater portion(s) in order to enhance the sealing of the assembly in the most critical areas thereof.

Abstract: Laminated heater plate assembly is formed from a plurality of layers of glass cloth and/or glass mat and epoxy resin which are laminated together under heat and pressure. One or more thermally conductive heater members are mounted in a cut-out region(s) in a pre-cured or "C" stage laminate top portion of the assembly while a plurality of uncured or "B" stage glass mat and epoxy resin laminations are stacked, assembled under the "C" stage portion and heater portion(s), and bonded to each other into a rigid, warp-free heater plate assembly which can be repeatedly subjected to steam or hot water without damage. Preferably, the resin density after bonding in the region of the edges of the heater portion(s) and the adjacent surrounding edges of the cut-out region(s) is greater than in locations spaced further from the heater portion(s) in order to enhance the sealing of the assembly in the most critical areas thereof.

Abstract: Conductive or semi-conductive elements which may be utilized as heating elements are manufactured in a continuous process utilizing a method known as pultrusion. The elements are prepared by forming semi-cured sheets comprising a support containing a mixture of a conductive or semi-conductive powder and a resin. The semi-cured sheets are fitted with conductive buss bars to form a conductive or semi-conductive element which is thereafter encapsulated in a glass roving-resin mixture to form the desired element. This element is then pulled through a heated die to effect the desired physical shape and thereafter may be cut to the desired size.

Abstract: Pressure-sensitive flexible resistors comprising an elastomeric material containing a controlled resistive element or material are prepared by impregnating an elastomeric material such as a rubber with a semiconducting carbonaceous pyropolymeric inorganic refractory oxide material.

Abstract: A wood veneer laminate form of heating panel incorporates an internal layer of a semiconductive carbonaceous pyropolymer, consisting of carbon and hydrogen on a high surface area refractory inorganic oxide support, to provide electrical resistance radiant heating. The carbonaceous pyropolymer in powder form can be incorporated with the glue line between veneer or core stock layers or mixed with a resin to be impregnated into a glass-cloth, or other support material, to form a conductive prepreg sheet which can be placed between wood veneer layers.