Remove the door from the hinges. Depending on how the door is hung, this involves loosening the screws from the hinges and pulling it away from the frame or removing pins holding the door in place.
Set up two sawhorses on a plastic tarp. Lay the swollen wood door on the sawhorses and allow it to dry out completely. Expedite the drying process by installing a space heater in the room or running a blow dryer over the door. Avoid setting the space heater within three feet of the door, as it will begin to drip water once the ice melts.
Dampen a rag with automotive lubricant. Apply a light layer of the automotive lubricant over the entire surface of the door. Automotive lubricants displace the water from the wood, removing any lingering moisture that will refreeze.
Cover the door with a fresh coat of varnish. Using a natural-bristled paintbrush, apply the varnish to protect the door from future water damage. Allow the first layer of varnish to dry for at least three to four hours before applying a second coat.
Allow the final layer of varnish to dry for at least 12 hours before rehanging the door.