Use a solution of mild soap and warm water along with a soft cloth or sponge. Once cleaned with this solution follow up by wiping away any residue with fresh clean water.
This process should be completed several times throughout the year to prolong the life of the finish.
Avoid solvents, abrasives, and harsh chemical cleaners. Where a solvent is absolutely necessary to remove materials from the surface, such as adhesives, the weakest possible solvent should be used (e.g. methylated spirits or 70% isopropyl alcohol). This must be followed up by using the basic cleaning tips from above.
Do not use acetone or commercial cleaning solutions.
For outdoor lockers a light waxing is recommended for the exterior surfaces to decrease the effects of harsh outdoor environments.
Wax the exposed surface semi-annually. Lightly wax the coated surfaces with a high grade, non-abrasive car wax that contains a U.V blocker and/or U.V. inhibitors. Do not use compound waxes that contain abrasives and be sure to wipe off any residual wax.
UPDATED: October 29, 2020