Just like with concrete, maybe you are willing to spend some extra money on an extravagant and masterful bronze finished garden urn. If so, you may want to polish it up from time to time. To start, ensure that you put on a pair of cotton gloves as the oils in your fingers can actually cause the bronze to corrode. Now that that is settled, remove any dust from the bronze urn by merely wiping it with a soft cloth. One last thing; rub some mineral spirits onto the bronze to rid it of any grease on its surface.
Finally, you are ready to begin and do so by mixing together a thick paste of denatured alcohol and powdered chalk. Take a clean cloth and begin to rub the past into the surface of the bronze urn. Do so in a buffing motion and depending on the level of oxidation, you may need to apply the past multiple times. To finish, wipe off the excess paste and seal it with metal max.