We use Renaissance Wax to protect the finish of all of our buckles once they have been polished and we believe that it is the best product of its type available. A micro-crystalline wax formulated originally in the British museum and used in museums and private collections worldwide the wax provides an invisible hard shell to metal fittings that helps protect the finish from tarnishing in a much more subtle way than the ugly plastic lacquer used by most other makers.
The wax should be applied sparingly with a clean, soft cloth and gently polished to a clear shine. A 65ml pot will last for a very long time and has a myriad of other applications in the house. If you wish to maintain the finish of your buckle as new an application of Renaissance Wax once a month after cleaning is highly recommended.