Leather shrinks due to several different factors. Hot water is one of the quickest ways to shrink leather, but it will not work as well without the addition of rubbing alcohol. Rubbing alcohol strips the leather of any protective barriers and allows the water to soak deep into the pores of the leather. Using a water and alcohol mix is a much more effective way to shrink leather than simply using water alone. You can repeat the shrinking process as many times as you like, but the leather will not get much smaller after the initial shrinking.
Mix one part hot water with one part alcohol. Fill a bucket about half way with this solution.
Place the leather inside the bucket. Sink the leather into the water. Allow the alcohol to soak in the water for about 10 minutes.
Remove the leather from the water. Rinse the leather with cool water. Gently wring out excess water.
Place the leather in a dry place away from direct sunlight to dry. Allow the leather to dry for at least 24 hours before using it.
Condition the leather with a leather conditioner and soft cloth before using. This will soften the leather and restore the protection that the alcohol and water stripped. Use circular motions to rub the conditioner into the leather. Allow the leather to sit for 24 hours, then give it one final coating of conditioner.