Cast iron window hardware is arguably more similar in use to cast iron radiators than frying pans, though all are made of the same material - I think.

There is good information on the internet about renovating cast iron radiators. I think the answer is to paint the hardware, just like people paint radiators.

http://www.doorsixteen.com/2013/08/29/refinishing-cast-iron-radiators-small-budget-edition/

Here is a link that might be useful: Cast iron radiator reno

It is probably wrought iron or mild steel which should be painted or powder coated.

Hello,

I also have cast iron window and door hardware. Use either steel wool or a steel bristled brush to get the rust off. Just coat it in something immediately after to keep it from rusting again. What you coat it in depends on the look you want. If you want a black wrought iron look- paint it. If you like the clean cast iron look it will have to be oiled immediately after cleaning. If it is something that gets handled often, like a lock or pull bar the oils from your hands will build the patina up enough to where it shouldn't have to be oiled too regularly, If you are talking about a hinge, you will have to keep it oiled. You can also put a clear coat of shellac on too if you want the clean look to be maintenance-free.

Check out our blog link below to see some of our hardware cleaned up.

Here is a link that might be useful: http://1885prospecthill.blogspot.com/2014/10/its-in-details.html