film of porous expanded ptfe was manufactured according to the teachings of u s pat nos 3 953 566 and 4 187 390 the finished film had a thickness of about 0 0015 inches a porosity of 80 a mass unit area of 17 g m 2 an inverted cup moisture vapor transmission rate of 24 000 g m 2 hr according to astm e96 a teledyne gurley value of 11 seconds according to federal test method std no 191a and a maximum pore size range of 0 2 2 0 microns determined by a methanol bubble point test according to astm f316 86 a sheet of film was cut to a size larger than the inner surface of the knee brace one surface of the film was sprayed with bostik supertak u2122 adhesive number 150724 middleton mass the inner surface of the inverted knee brace was placed into contact with one edge of the adhesive coated film surface and rolled across the film surface under hand pressure causing the sheet of film to adhere to the inner surface of the knee brace the adhesive was then allowed to air dry at room temperatures for one hour the excess film was then trimmed from the edges of the knee brace after which the knee brace was again inverted so that the film covered surface was on the.