Rust converter question

I really like Ospho brand rust treatment. It works great, and here is a link where I bought a qt. last spring. I usually brush it on with a foam brush, let it soak over night, then paint. For hard to reach areas I put some in a spray bottle. A qt. goes a long way, so it's not really that expensive IMO.
Bob

http://www.jamestowndistributors.co...gine=adwords!6456&keyword=(oshpo)&match_type=