Polyurethane stains on park chairs can be unsightly and challenging to remove, but with the right techniques, you can restore their appearance. Start by wiping off any excess polyurethane with a dry cloth before it dries. For dried stains, use a mild solvent like mineral spirits or rubbing alcohol, applying it gently with a soft cloth or sponge. Avoid harsh scrubbing to prevent damage to the chair's surface. For stubborn stains, a mixture of warm water and mild dish soap can help loosen the residue. Rinse thoroughly and allow the chair to dry completely. Regular maintenance and prompt cleaning will keep your park chairs looking their best.