- 1). Open the antique door to a 90-degree angle. Fit wood shims under the door to prop up the end.
- 2). Tap the pins in the hinges up and out with a chisel and hammer. If the pins will not easily come out, pull them out of the hinges with pliers.
- 3). Pull the door off the hinges once the pins have been removed and lay it flat on a workbench or table. Do not place the antique door on sawhorses, as this may worsen the warping problem.
- 4). Apply a coat of polyurethane to the bottom, side and top edges of the antique door with a paintbrush. Let the polyurethane dry between 12 and 24 hours, following the manufacturer's instructions.
- 5). Rehang the antique door, resting it on the shims and tapping the pins back into the hinges with a hammer. Remove the shims from under the door.
- 6). Close the antique door and leave it locked for five to seven days. As the wood dries out, it should return partially or fully to its original straight position.