I'm refinishing a Fender body that has thick poly, so I thought I'd give Citistrip a shot, rather than just sanding like I normally do. It does say on the label it works on polyurethane. I applied it, waited a couple hours, and took a putty knife to it. The poly only laughed at the Citistrip. Giggled, even. No effect on the poly whatsoever. Just thought I would pass that on to possibly save you some trouble.