Polyethylene foam (PE foam or PEF), sometimes referred to as expanded polyethylene (EPE), is a strong and stiff closed cell foam. Laser processing of polyethylene foam is possible with either a 9.3 or 10.6 micron CO₂ laser with little appreciable difference in process quality. The energy from a 1.06 micron fiber laser is not readily absorbed by polyethylene foam and is not recommended for laser processing. Laser cutting of polyethylene foam with a CO₂ laser creates a clean cut with no discoloration. Laser engraving of polyethylene foam with a CO₂ laser produces depth with defined features. Marking of a polyethylene foam is not recommended using the 9.3, 10.6, or 1.06 micron wavelength.