substrate substrates penetrated by or resistant to 100 water 0 isopropyl alcohol the least penetrating test liquid were given a rating of 0 substrates resistant to 100 isopropyl alcohol 0 water the most penetrating test liquid were given a rating of 10 other intermediate ratings were calculated by dividing the percent isopropyl alcohol in the test liquid by 10 e g a treated substrate resistant to a 70 30 isopropyl alcohol water blend but not to an 80 20 blend would be given a rating of 7 oil repellency or the oil repellency of substrates was measured using the aatcc procedure standard test method no 118 1983 the oil repellency of the substrates are expressed in terms of the u201c or u201d rating dry soil resistance the dry soil resistance of substrates was measured using a method described in u s pat no 5 370 919 a value of 5 indicates that there is no increase in soiling versus an unsoiled sample a dry soil rating of 1 indicates that the substrate was severely soiled to determine the amount of fluorine in the extruded fiber described in the examples the following method was used a known weight of the sample was placed in an ignition basket made from platinum wires the sample was then decomposed in.