I would like to paint the floors of my Campbell, but before I do I want to put a coat of resin over the old glasswork to fill and smooth the surface. I have easy access to poly resin, but the hardener has wax added. Do I need to sand the surface of the old glass to prepare for the resin? Should I start with a thinned coat to penetrate and then follow up with a thick coat applied before the 1st fully cures? Or just go straight to the unthinned resin. I assume that unless I can find some laminating hardener I have to sand any cured new resin before applying anymore. Is it the same with the 25 year old original glasswork too?