Foamcore

From CosplayWiki

Foamcore is a strong lightweight, easily cut material useful for backing, mounting photographic prints, framing, 3D design and painting. It consists of three layers — an inner layer of Styrofoam®, 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 under the trade name Fome-Cor. The surface of the regular board is slightly acidic. For archival photo purposes Monsanto produces a neutral, acid-free version. Similar products are now available from competitors in a wide range of sizes and thicknesses.

This material does not hold up well to some glues, such as super glue, and certain types of paint. The foam tends to melt away and dissolve. While Elmer's White glue works well in casual settings, the water in the glue can warp the fibers in the outer layers. Best results are typically obtained from the higher-end spray adhesives like 3M's Super 77. In situations where a craft store is either not nearby or closed, a hotglue gun can be used as a substitute, although the low viscosity of hot glues can show up in finished projects with board warp, bubbles, or other unsightly blemishes.