I finally got around to try out our Polyurethane on some scrap nylon fabric. Unfortunately I didn’t have a brush handy and there was some unsecurity about the ratios, but everything stuck and penetrated the cloth well. I even overcolored the remaining PU just to get a worst case scenario, but it didn’t make bubbles and it seemed to penetrate the cloth just as well. And that was actually after the stipulated potlife of 10 minutes, not bad for a first test!
I only had a stick to apply it with so the “artwork” is pretty much unintended. Just tried to make it unneccessary thick in places in order to do some sharp knife tests when it’s fully cured.
When the goo got gooier, like barely melted chocolate, I tried some on my kayak’s ends which had taken some scraping. Applied everything with a small ice cream stick. It stuck, it cured and it’s impossible to get off there, so it seems it even sticks to old PU, which is very good and unexpected! Tomorrow I will try to make “keel strips” out of PU on the kayak.