Please give me some advice.
My beloved tarp (not the blue/grey thing you buy from Costco) needs some TLC. It is a 5m x 5m (269^ft) awning type tarp, and has been with me through thick and thin. The undercoating (urethane) has completely faded away, and no longer provides water-proof protection. The result is rain dripping through the fabric.
I could purchase a new tarp from the manufacturer (in Japan) for $270. I would like to simply apply a urethane coating to the underside, and give my tarp a few more years of use. But I can't find urethane in the quantity that I need (and, at the price that is required). Any ideas?