In my business we have used this a great deal and works very well. I have done several old metal / iron items that went down to the Bahamas and just sit out in the open air. As far as I know this company is the only place you can purchase it at this time. Looks like thin milk when you paint it on and drys clear with a black tint. I have even sprayed it in a regular cup spray gun. Really does soak in and attack the rust and seals it.
http://www.blastandpaint.com/pdfs/RUST CURE.pdf
http://www.blastandpaint.com/pdfs/RUST CURE.pdf