Have been wanting to try this for ages as they rave about it in the States so bought some Oxalic powder off Ebay.
Mixed to a ratio 25g OA powder per 100ml water and put in a container and c'est voila an OA bath.
BTW I found it better to use boiling water to get it to dissolve.
Very badly corroded seat guts.
Dismantled the seat guts and put the parts into the OA bath, which turned yellow with a metallic smell.
Left for 24 hours then checked to find rust was gone, however, there was some sporadic black scale left on the parts.
Scraped it off to find the red of rust underneath so put the parts back into the OA bath for another 24hrs.
Parts taken out after second bath, rinsed in cold water, rust all gone, the parts are now grey/green.
Cleaned the parts with wire brushes and jobsaguddun, they turn out like the part on the right below.
More pics after cleaning which I'll add when I get a chance.
IMPORTANT - At this stage it is back to being raw steel, the chrome, zinc or cadmium plating protection is gone, you have to protect it ASAP or it will rust again very fast, I'm going to use zinc galvinising spray.
The OA will dissolve the rust completely off some parts but others will require agitation.
I tried to make the acid stronger but found that the OA powder will crystallize leaving the liquid in the container weaker, so I reckon the 25g to 100ml ratio was just about right.
The oxalic acid will not dissolve the steel as some crackpots seem to think, it will dissolve the rust and the metal left will be thinner, if the only thing holding your frame together is rust then it will dissolve.
