How to clean old license plates

[jmartins413]

Over the summer i was digging in a bottle dump in New Hampshire and I found a stack of 12 license plates from 1930 - 1939. All the metal seems to be solid, there is just a lot of heavy surface rust on them.
I came here to see if anyone had suggestions for cleaning them.
These are some of the license plates

 

[mojjax]

there is a product called METAL RESCUE . it works good .

 

[Professor of Engineering]

Awesome old plates, congratulations!

 

[A2coins]

Very collectible nice find