....so I did foam brushed the underside of my diy tarp leaving the front side untreated. The heat of the midday sun sets up the sil fast so I did pretty much what Patches did, mixed it in small batches. I pressed the foam somewhat hard against the fabric to force the sil to sip through, and with my other hand on the other side countering it. Brushed one side and went back on the other side for second coating. I concentrated on the ridgeline and the upper half part coz I think thats the most critical. Im satisfied with the finish job, smooth and without drip marks. For the solvent I just used an ordinary paint thinner, the smell is gone after letting it dry for 24hrs. It rained this morning so I made a quick setup to test the tarp. I stayed inside it for about an hour to check for any leaks and there was none. I was happy but not fully satisfied coz it was just a light rain. A storm is coming in this weekend so we'll see how it performs.