Charmeuse (French: [ʃaʁmøːz]) is a lightweight fabric woven with a satin weave, in which the warp threads cross over three or more of the backing (weft) threads. These float threads give the front of the fabric a smooth finish—lustrous and reflective—whereas the back has a dull finish. It can be made of silk or a synthetic lookalike such as polyester. Silk charmeuse is more expensive and delicate but is softer and a better insulator. Polyester charmeuse is cheaper and can often withstand machine washing, but it does not breathe as well as silk. Charmeuse differs from plain satin in that charmeuse has a different ratio of float (face) threads.