I've used straight vinegar a lot, and it works very well - see photo. Haven't tried adding lemon juice and salt yet. Vinegar immersion in half day increments is about right. If it's not good enough yet, give it another half day, and check again. Afterwards, a simple rinse in hot water with dish soap, followed by thorough hand wire brushing prevents flash rusting. That photo was taken January, 2011, and 15 months later, those parts still look exactly the same, awaiting phosphating.

I've also been experimenting with Evaporust, which is a heck of a lot more expensive than vinegar. It works a lot faster than vinegar - inspection every 1-2 hours is about right. Evaporust can't seem to quite get the job done right without some help - usually some elbow grease with sandpaper or wire brush is needed, which is okay with me. I think it is always best keep the exposure to the chemical solution (whatever it is) to the absolute minimum needed, not any more. Periodic removal from the Evaporust or vinegar and inspection to find stubborn places that need some minor physical rust removal with sandpaper, wire brush, or light scraping with a file will shorten the immersion time a lot.

If using a costly rust remover like Evaporust, it's best to remove all loose and easily removeable rust by hand before immersion. That way, you aren't wasting and depleting the strength of the chemical needlessly.

I went to buy some white vinegar and all i could find was a watered down mixture to 5% acid (said on the label).Is this what everybody is using? Be nice to find full strength somewhere then dilute to what would work. It was 2.98 gal. walmart.

How much do you think it would cost to fill a swimming pool so I can dip my car into it

from my experience with different products, EVAPO RUST is the stuff to use. for a 5 gallon pail its about $99-115 depending where you buy it. a definite pro of this product is that its safe for the environment as well and can be disposed of easily. works on all metals and does not affect paint either. once parts are submersed in the solution just check up on it every 1-2 hours or if its badly rusty, let it sit for a few days. It has not damaged one part yet.

Here's the after photo. To get rid of the flash rust, I coated the backing plate with Rust Cure (www.rust-cure.com) using a cheap nylon bristle brush and thoroughly wiped the Rust Cure off immediately. Another application and wiping off may be needed. If you don't wipe it off, there is a residue that can be removed with re-application of Rust Cure and wiping.

Rust Cure is a phosphoric acid-based rust remover, similar to other phosphoric based solutions but stronger. For most rust removal, I am using EvapoRust or vinegar, but Rust Cure is very good to fix flash rusting until you can finish restoring the part.

My backing plates were all originally phosphated, so that's the way they will be restored. When it comes time to phosphate, I will wash off the Rust Cure, do a final pickle in vinegar, and immerse in the phosphating solution.

For parts that need to be painted, apply paint on top of the Rust Cure - do not remove it. Allow one week Rust Cure drying time before painting.

For parts that were originally bare metal, the medium gray appearance left by Rust Cure may be too dark. You can remove the Rust Cure with a hot wash, then hand wire brush for a few minutes to get more metal shine. Then immediately coat with wax, RPM, or similar. To get the right balance of gray vs. shine, you can experiment. Generally bare parts of flat, thin metal were cut from cold rolled steel that was shiny, while thick parts were cut from hot rolled/pickled & oiled steel that was gray and less shiny. The Rust-Cure gray should be about the right color for rear spring brackets and the spring plates with shock absorber mounts.

For bare metal parts that were forged or heat treated, such as suspension parts, there have been several posts here about using gun bluing followed by RPM. You can remove the Rust Cure by washing, then hand wire brush, then apply bluing and RPM. I haven't done this yet - it may work to put the bluing on top of the Rust Cure.

http://www.rustremover.net/

I buy 5 gallon pails of Evaporust from these guys.
Shipping is reasonable, by the UPS people.

It's amazing how these things snowball. I bought the evaporust to do some small parts and didn't expect much. I've always been a blast it with something kind of guy. I was amazed at what it did. So typical 40+ year old kid I got the rustiest pieces I could find to see just what it would do. Still amazed. I cleaned up a set of shoulda been throwed away rear sway bar supports and even found some inspection marks along the way that I didn't expect to find. I'm not easily sold on new products but it works and doesn't try to destroy what lungs I have left or eat my skin off. 2 good extras! I've been just cleaning the parts with hand cleaner and Dawn with water and then shooting on some WD40 till I can do something with it. Here comes the snowball. I've done about every trick known to man for natural metal parts. So here I am with a pile of parts that need something. So I order the RPM. I'm sceptical at first but now I love it. The process takes a little time to get on to, but the alternatives are twice as much work. I'm trying the homemade stuff on a rear center as soon as I get it clean. I need 3+ gallons to soak it in a 5 gallon bucket and evaporust is just to pricey for that. I posted some pics of the stuff I've done so far. Question, has anybody soaked a carb in it like the bottle shows on the evaporust?

on small stuff i have had good luck dealing with flash rust by lightly steel wooling the part after dipping the wool in SEM Rust-Mort. rust comes right off....and doesn't reflash.

my local autozone stocks gallons of evaporust for $19.

Just curious, I didn't see it mentioned in this thread but would running newly cleaned parts through a dish washer remove and neutralize the acids?

Btt

I again tried the lemon, vinegar, salt combo on some old wrenches and it worked very well. I had a bunch of very old year wrenches of all makes and styles up to 2" being 20" long and the soak worked very well. Some of them are really weird, and super old, and they really cleaned up nicely.

I'm going to try this solution in my heated ultrasonic to see what it does on really bad stuff. Easier than bead blasting, and cheaper than anything else.

Good tip, that's why I'm bumping it again, thanks OP.

It does work good. Recently tried the battery charger water solution and it's amazing how good that works, very simple and better for cast iron I'm told.

what's the battery charger water solution?

Google "Electrolic Rust Removal"