How to Remove Polyurethane From Granite

Open windows for ventilation. Use a fan to circulate the air during the process of removing the polyurethane from granite.

Clean the area of granite you wish to remove the polyurethane from with a damp cotton rag. Allow the granite to dry.

Put on plastic gloves to protect your hands.

Apply stone stripper to one area of the granite using a clean, dry paintbrush. Allow the stripper to lift the polyurethane for a few minutes. Slide a plastic putty knife along the area where you applied the stone stripper until the polyurethane is removed. Repeat the process in small areas on the granite until the stripper is removed.

Wipe the granite with a cotton rag dampened with warm water to remove all of the stripper. After you remove the polyurethane and clean the surface, spots where polyurethane settled are visibly shinier than other areas of the stone. Reapply stripper to those areas with the paintbrush. Remove the stripper with the plastic putty knife and wipe the residue with a cotton rag dampened with water. Allow the granite to dry completely.

Use a sander with fine-grit sandpaper to remove remaining residue from the granite. Evenly and lightly sand the spots with remaining residue. Use a vacuum to remove the dust. After removing the dust, wipe the granite with a cotton rag lightly dampened with warm water. Repeat the sanding process if residue remains.