Wash the inside and outside of the trunk with a mild soap, like dish soap and warm water. Rub the mixture over the surfaces with a soft sponge. Dip the sponge in fresh water and rub over the surface again, removing the soap residue. Turn the hairdryer on low and hold it a few inches from the top, moving it back and forth until you dry the trunk.
Run your hands over the trunk, feeling for any loose leather pieces. When you find a loose piece, push the edge of the butter knife under the leather and wiggle it slightly, loosening the leather from the wood. Apply a thin coat of wood glue to the surface of the trunk and press the leather down. Rub your hands over the top, pushing out any air bubbles and let sit for 24 hours.
Scrub any rusted areas of the hardware with a wire brush. Wipe off any rust or metal shavings that come off the hardware. Rub the hardware with a thin coating of clear metal varnish. The varnish brings back the natural shine of the hardware and prevents future rust.
Rub the leather areas of the old trunk with a specialty leather soap. The leather soap restores the natural look of the leather by bringing back its natural moisture. Treat the surface with leather oil, rubbing the oil onto the leather in a circular motion.
Fill any holes on the inside of the 1800s trunk with wood putty. Press the putty into the holes and let sit overnight. Rub the dried putty with 220-grit sandpaper, making the putty sit even with the surrounding wood. Repeat the process for any other holes, chips or damaged areas of the interior.