I am planning on scrubbing my tarp this spring with a cleanser. I am guessing this will harm the waterproofing. What is the best way to rewaterproof the tarp, and what products are good an don't cost a ton of money? Also will i need a sprayer to apply the product? Thanks for any info. Darren

I just did mine a little while ago.

On the driveway, I laid down a couple sheets of Painter's plastic, or you can use a tarp. Duct tape it to your driveway, lay down the cover on the plastic and use a soft bristle brush on a long handle to wash it with some mild soap or boat wash. Hose it off and let it completely dry.

I applied the waterproffing with the same brush. Dunk it in a bucket with waterproofer and let it soak in really well, using the brush to really get in between all the fibers.

After if was done, it repels and beads water like never before.

I washed mine and used 303 water repelent, it worked great................

Where can i get large quantities of waterproofing?

Cheap silicone spray.
Good as any spray waterproofer out there.

I bought some at either west marine or boat us by the gallon and sprayed it on with my paint sprayer . It worked pretty good and tidn't tale very long.