Plaster or bandage has a backing sheet provided with adhesive and the sheet being a gas permeable, water impermeable membrane, made of a semi-interpenetrating polymer network. Pref. the polymer comprises fibrillated polytetrafluoroethylene and crosslinked polyorganosiloxane. The backing sheet may be transparent or translucent and is pref. waterproof upto 200 p.s.i. The adhesive is pref. pressure sensitive. Absorbent gauze can be provided.
