I just got the email response - the thompson fabric waterproof stuff is silicon.
So it looks like the only way to add PU back to the material is to buy the aquaseal poly coat or similar stuff.
I agree with warbonnetguy about using silicone. I suggest Permatex "Floable Windshield Sealant" because it is already the right consistency, and trying to make a slurry with mineral spirits is not really adequate -- although that has not kept lots of folks from trying it. Be sure to clean the fabric thoroughly with rubbing alcohol before applying any sealant.
Thanks - do you paint it on or soak the material in it?
Originally Posted by Spock