What is "foamcore"

Foamcore or Foam board is a 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.