Removing rust with citric acid...

[b5blue]

OK now for testing, insert one rusty hunk of 70 Charger Dutchman panel into a glass pan with 5% citric acid and now we wait....... 

[b5blue]

  Well good results! Yesterday it looked like not much was going on so I poked my finger at a spot and flakes of rust freed themselves. I scratched around with my fingernail and saw bare steel. Today I lightly rubbed the flat end of a small pry-bar across the surface and the rust detached like small corn flakes.
  I ran some errands and came back about 2 hrs later, I pulled the sample and hit it with tap water and a well used green scrubby lightly scuffing the rust. With no real effort this is what resulted:
   

[b5blue]

  This mix does not so much dissolve the rust, it lifts or separates it off the steel. You can see the flakes left in the pan. 

[JB400]

 

[Dino]

Stuff works doesn't it?      

[b5blue]

YUP, I'm sold that was 43 years of real rusted Charger.

[jt66383]

Now you just need a really big tub..... or maybe a swimming pool.... fill it with the citric acid and dunk the car in.... leave it for a few days, pull it out and you have a "rust free" charger.  LOL

This might be a new industry for the Orange Belt.
Jeff

[b5blue]

I was thinking of making a shallow tank out of 2x6's on my carport floor, lined with a thick plastic sheet. I could soak my hood in there a few days then pressure wash the thing between the support frame and skin. Speed up drying with alcohol and spray Rust Bullet or Rust Encapsulator between the two assembly's, 2 coats of epoxy prime and then paint. 

[69_XS29L]

I'm not a chemist, but I believe the point of treating steel corrosion with phosphoric acid is the fact that the heavy oxidation is is not only removed, but the remaining corrosion is converted to iron phosphate which is itself a corrosion inhibitor, similar to the black oxide finish on bolts and small parts we are all familiar with.
Citric acid can remove the rust, but on heavily corroded pieces may not necessarily penetrate into the pitting cells where corrosion starts, but you would be media blasting the worst of the rust first right? Whether or not you can see it or believe it, that shiny metal is oxidizing as soon as you finish drying it.   Alternatively, if the part is small enough to bathe, a mild caustic solution could be used with a DC power source to convert the rust back to iron through electrolysis with the same minor limitation as citric acid, the surface begins to oxidize almost immediately. On heavily corroded pieces this would have the benefit of salvaging some of the bulk and detail otherwise lost through stripping.
By the way, we use food grade citric acid in the oilfield to treat cement contamination in drilling mud. If you can find a drilling mud supplier with it in stock, it comes in 50lb bags for a little over 2 USD per lb. They should also have the medium grade walnut hulls or soda ash you can run as a less abrasive media in your sand blaster. Good luck,Mike.