There is a thin plastic film liner under my seat cushions and under my bed cushions. This liner looks and feels like drycleaners plastic. You know the stuff that they use to cover the clothing. I think that this is used as a vapor barrier of some sort. It does keep the moisture out of the cushions if there is a sipll.I need to replace some of this and am looking for a source. Last year I lost some of plastic when I cleaned the cushions.I have searched the archives and cannot find mention of the stuff.