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Foamcore, Kappa or Foam board is a very strong, lightweight, and easily cut material used for the mounting of photographic prints, as backing in picture framing, in 3D design and in painting. It is also in a material category referred to as "Paper-faced Foam Board". It consists of three layers — an inner layer of polystyrene foam clad with outer facing of either a white claycoated paper or brown kraft paper.
The original white foamcore board was made in 1/8 inch (3 mm) and 3/16 inch (5 mm) thicknesses for the graphic arts industry by Monsanto Company under the trade name "Fome-Cor" starting in 1957.[dead link] Monsanto sold the business to International Paper in 1993, and the business is currently operated by 3A Composites. It is now widely-used as backing in art and document mounting and picture framing, with archival-quality variants now available from several companies. It ranges in thickness from 1/16" - 1/2". It is not recyclable or biodegradable in normal situations.
Construction, variants and composition 
The surface of the regular board, like many other types of paper, is slightly acidic. However for modern archival picture framing and art mounting purposes it can be produced in a neutral, acid-free version with a buffered surface paper, in a wide range of sizes and thicknesses.
Foamcore does not adhere well to some glues, such as superglue, and certain types of paint. The foam tends to melt away and dissolve. Some glue works well in casual settings, however, the water in the glue can warp the fibers in the outer layers. Best results are typically obtained from higher-end spray adhesives. A hot glue gun can be used as a substitute, although the high viscosity of hot glues can affect finished projects in the form of board warping, bubbles, or other unsightly blemishes.
Self-adhesive foam boards, intended for art and document mounting are also available, though these can be very tricky to use properly; this is because the glue sets very fast. It is considered cheaper to buy plain foam board and then re-positionable spray mount adhesive.
Foamcore is commonly used to produce architectural models, prototype small objects and to produce patterns for casting. Scenery for scale model displays, dioramas, and computer games are often produced by hobbyists from foamcore. It's also often used by photographers as a reflector, in the design industry to mount presentations of new products, and in picture framing as a backing material; the latter use includes some archival picture framing methods, which utilize the acid-free versions of the material. Another use is with aero-modellers for building radio-controlled aircraft.