Abstract: A flexible camouflage base material includes three layers, one being a layer of non-woven, flexible, electrically nonconductive polymeric material, a second layer of substantially identical material, and a third layer lying between the first two, the third layer having two sets of strands, the first and second layers being bonded to the third layer and to each other through openings in the third layer. The third layer includes a first array of strands spun from polyamide or polyester fibers and electrically conductive fibers, such as stainless steel or graphite, the strands being arranged in parallel relationship with each other and lying in a plane parallel to the first and second layer. The third layer also includes an adjacent array of strands of the same nature as the first array, the strands of the second array being disposed at an angle to the first to form a plurality of parallelogram-shaped openings. The larger angles of the parrallelograms thus formed are between about 100.degree. and about 105.

Abstract: A buoyant swimming pool cover in the form of a flexible lightweight sheet comprising a large plurality of hollow buoyancy cells spaced apart over the sheet, there being a plurality of drain apertures distributed over the sheet in areas thereof not occupied by the buoyancy cells and serving to allow rain water to flow through the cover into the pool. Best results are achieved when the configuration of the upper surface of the cover presents depressions serving to direct into the drain apertures any water falling onto the cover. Advantageous embodiments are in the form of a lamination of at least two polymeric films at least one of which has been thermoformed to provide generally cup-shaped portions which are closed by another of the polymeric films. Since water cannot collect in any substantial quantity on the cover, the cover can be very lightweight and is always easily lifted off the water, without any dirt or debris which has collected on the cover being carried into the pool as the cover is removed.

Abstract: The invention refers to heat weld joints of the type used for adjoining webs of reinforced plastic foil intended for use as stretched ceiling covers. The invention consists in the provision of means at intervals along the heat weld joints for reinforcing same to withstand the influence of heat. The invention also covers a process for the preparation of such reinforced heat weld joints.

Abstract: Laminated, radar-defeating camouflage material for use under snowy, low-temperature conditions without delamination or undue decrease in flexibility at temperatures at least as low as -40.degree. C.

Abstract: When manufacturing camouflage sheets of substantial size, the camouflage pattern is normally printed or punched in repetitive consecutive steps so that a pattern repeat may be seen and impairs the camouflaging effect. The invention makes it possible to considerably increase the pattern repeat, i.e., the distance after which the pattern repeats itself on the sheet without increasing the size of the pattern, in that the sheet and the tool such as a printing plate are angularly displaced relative to one another in their own plane so that the pattern is repeated a number of times on the sheet such that adjacent areas of pattern are angularly displaced (turned) relative to one another. Thus, the pattern of each such area is in another angular position than the identical preceding pattern and the identical subsequent pattern.