Abstract: A surface of a hydrophobic microporous thermal insulation material is coated by first heating the surface of the microporous thermal insulation material so as to provide a hydrophilic surface layer on the hydrophobic material. Subsequently, a water-based coating, such as a water-based silicate adhesive, is applied to the hydrophilic surface layer of the hydrophobic material. An abrasive-and/or impact-resistant cover, such as a glass fibre cloth, may be applied to the coating.

Abstract: A coiled heating element is manufactured by providing a coiled element of bare resistance wire in which the coil pitch is not greater than twice the cross-sectional dimension of the wire. The element is stretched by an amount permitting recovery to its original configuration and an electrically insulating particulate material is applied to the stretched element. The stretched element is then allowed to return towards its original configuration thus trapping particulate material between adjacent coils of the element and the element is heated so as to oxidize the surface of the wire.

Abstract: A method of manufacturing a microporous thermally insulating body comprises mixing together a finely divided microporous insulating material such as silica aerogel or pyrogenic silica and a solid ammonia-generating compound in particulate form, and compressing the mixture to form a thermally insulating body. The ammonia-generating compound is dispersed evenly throughout the insulating material and may comprise, for example, ammonium carbonate, ammonium acetate or urea. Preferably, the ammonia-generating compound comprises a mixture of about one third by weight of ammonium carbonate and about two thirds by weight of ammonium bicarbonate together with a small proportion of magnesium oxide.

Abstract: In the radiant heater for an electric appliance such as a cooker, the heating element is secured by glue on stakes automatically inserted into and held by friction in a compacted layer of microporous thermal insulation.

Abstract: A panel of microporous thermal insulation material is manufactured by applying a film of polyvinyl acetate emulsion to a non-porous substrate, such as a sheet of steel, and compacting powdery microporous thermal insulation material against the film so as to cause the consolidated insulation material to bond to the substrate and form a panel.

Abstract: A panel of microporous thermal insulation which comprises an envelope of glass fibre cloth which surrounds and is bonded to a block of microporous thermal insulation is manufactured by heating the glass fibre cloth so as to drive off organic material, applying a silane in an acidic solution to the cloth, drying the cloth in order to produce cross-linking of the silane so as to cause the cloth to stiffen, and applying to the cloth an aqueous suspension of particulate silica, an aqueous solution of sodium silicate or potassium silicate, or a cellulose solution. Microporous thermal insulation is introduced into a bag mode from the cloth and the bag is then compressed to consolidate the insulating material and to produce a bond between the insulating material and the bag.