XPS insulation boards begin as a solid granule. The granules are fed into an extruder where they are melted and critical additives are mixed with the viscous fluid that is formed. Then, a blowing agent is injected to make the mixture foamable. Under carefully controlled heat and pressure conditions, the foamable mixture is forced through a die, at which time forming and shaping occurs. The rigid foam is then trimmed to the final product dimensions and is often manufactured with a distinctive color to identify product brand, blue for Kappa Systems.