I did some rust research a while back and learned that there are a lot of products to stop it. Old bridges, churches with iron work, farm equipment....all that sort of stuff has to be preserved. Otherwise, you're talking a lot of money!
So, I found several "industrial" grade convertors on the market. Here's one, but there are many more. Google!
http://www.interstateproducts.com/rustkiller.htm