Once the relic is cleaned up and completely dry, it is time to preserve and prevent the rust from taking over again. Some people use a clear coat of spray paint, but this can have adverse effects. It can also cause even more rusting in the future if done incorrectly.
The best proven methods for preserving these types of relics use wax. There are a couple of wax preserving methods that work really well. You can use car wax as long as it does not have any type of abrasive material in it. Briwax works great. It helps to seal the relic and prevent moisture damage.
You will have to apply several coats and buff the relic between each coat. If done correctly, you should have a nice protective barrier that will last for years to come.
The other method involves quite a bit more work. You have to use Microcrystalline Wax. If you intend to use this method of preservation, then you will not have to dry the iron relic. Submerge the relic into a heated vat of Microcrystalline wax. The perfect temperature is right around 175 degrees Fahrenheit (79 degrees Celsius). The iron relic must stay submerged until no more bubbles emerge from the vat of hot wax.
Once this happens, the wax is then cooled and the iron relic is removed and any residual wax is removed immediately. This method produces a long lasting barrier that will not yellow and it will prevent any future rust.