If you use the liquid try treating all your flies at home and letting them air dry for a day or two. I usually use the paste type, not sure which brand mine has a green label, they are all some form of silicone base substance. This is one of those cases where less really is better. I had even used bacon grease in a pinch when I went camping and didn't have anything with me. Just remember less is better. Just barely cover the material with the product or if the liquid let it completely dry before using the fly.
Hope this helps,
GD