Thought I would share my experience first time using this product.

http://www.evapo-rust.com/

It runs about $20/gal maybe less but thats about the best price I've found.

Anyhow I had this rebuilt head that had surface rust since I bought it on Ebay some time ago. Not horrible but more than just a wipe-off problem. Some small pits on the exhaust/intake. Had been tanked but not painted or treated to prevent rust. Thought it would be great use of this stuff.

Supposedly its "green" rust remover. Doesn't damage good iron, safe to use, no vapors, no safety equipment required. This I like.

So I made a head-sized box, lined it with plastic sheeting and soaked the head after removing valves and rockers. Label says twenty minutes, overnight for problem rust. Twenty minutes didn't do it. Left overnight and it looked very good. Rust had turned to a black slime.

Had other things going on so left it to soak until I could finish up. Opened it up two days later and it looked beautiful, at least to my eyes. Looks as good as a block fresh from the hot tank. Nice clean iron.

Directions say to spray off with water and then either dip it again and allow to dry or treat to prevent rust. I rinsed and then sprayed it down with WD-40 and wrapped it up in plastic bags until I can get back to it.

But I'm very happy with the stuff. I had my bare hands in it and didn't notice any affect to my skin so it seems pretty mild.

Wish I had before/after photos but I hadn't taken any "before".

Now if anyone knows what this stuff actually is that would be great. Hopefully its not just baking soda and soap with a 20 dollar price tag.

But it did work as advertised. I'll use it again.