I just made a trip to the auto supply store and found three other products to experiment with:

The most expensive with from Duplicolor and was a spray in truck bed liner that was available in 1 gallon cans for people with spray guns ( about $30 a gallon) The same stuff is also available in aerosol spray cans for about $7. The contents seem to be a lot of solvents and a vinyl compound. I suspect it has a pretty strong odor as it sets. The instructions say it takes a day to harden enough for use in your truck. If it soaks into the fabric, this could be a real durable coating.

Duplicolor also has a polyethylene based spray paint for recoating plastic bumpers. about $6 for an aerosol spray can.

finally, there was a synthetic rubber ( i think) based tire coating compound that came in a jar for about $4, and you could brush this stuff on.

I assume all these are flexible, would penetrate and waterproof the fabric while locking themselves into the fibers, as opposed to just sitting on the surface of the fabric.

As Henry Ford might say: All three are available in any color you want, as long as you want black.

If anyone tries these things, please post the results.

Paul G. Jacobson