Polystyrene, Extruded (XPS)

Updated 4/11/10 PAB

Alternate names
EPS - This name is commonly used for both expanded and extruded styrofoams, so it can be vague. Some users and vendors have taken to using "XPS" for extruded, and "EPS" for expanded.
Rigid Styrofoam
Rigid EPS

Characteristics
XPS is a stiff foam board usually blue, pink or green in color, depending on the manufacturer. It has a consistent texture which differentiates it from expanded (EPS) "bead board" styrofoams that crush more easily and produce small pellets that can damage some art work especially when trapped between canvas and stretcher. It is a less expensive form of thermal insulation than Polyurethane Ester. Almost all polystyrene is now CFC-free.

Forms/Sizes
It is commonly available in two forms 2 x 8 ft planks these sheets may be the only version available in some areas, the second more desirable form is in 4 x 8 ft sheets. Most common thicknesses are 2 or 1 inches

Illustrations

Applications
Used as thermal insulation in crates - usually in combination with Ethafoam (for cushioning) where it is important that all materials are chemically stable. XPS has a thermal rating of R-5 per inch thickness.

Source(s)
Building supply stores