Ren wax is a remarkable preservation product. It will stabliize deterioration of most surfaces and materials. It will not retard deterioration, however. Essentially, the wax will "freeze" further deterioration of the footlocker for a number of years.
Important to follow the instructions on the container.
Once rust takes hold, then it starts to actually dissolve or remove the base material - so it is fairly impossible to reverse. Removing the stuff in this case just needs soap and water with a non-abrasive brush.
It IS possible to fully restore artifacts like that footlocker - at rather high expense, and with the understanding that (as mentioned above) doing so will eliminate most of the visible history of the object.
So, with some gentle cleaning off of all dust and loose crud, then proper application of Ren wax... good to go in most cases. Yes, it works with leather and almost everything else. Leaving the numbers and letters as they are right now is probably best.
Some info about the wax:
Edited by Bluehawk, 16 November 2019 - 09:18 AM.