I don't think what you have is silnylon. A great test to find out(because silnylon "is" waterproof) is take a cup and force enough of the silnylon into the cup so that you can leave a couple of ounces in the portion that you push down into the cup. Leave it over night and if any water drips into the cup at all (through the nylon) you "do not have silnylon" That's what I was told and I did do the test myself on several fabrics and it worked flawlessly on the silnylon...sabre11004..