I was curious about any ideas or tips there might be for finishing metal for furniture. I have heard linseed oil suggested but am not sure how permenant a solution that is. I would prefer a durable hard type finish.
Any help appreciated, thanks

Oil and wax seem to be good options because they penetrate a little. I like to use spray lacquer, seems to be a thinner layer than paint and doesn't chip as much.

Are there many types of spray lacquer or do you recommend one?
It sounds worth a try

Birchwood Technologies Presto Black MKP
or
Birchwood Casey perma blue

If you want black and there is no mill scale.