Citric Acid and Rust
 

Okay, with some trepidation I did decide to start yet another rust thread. Has anyone ever used citric acid for rust removal? I did a web search, and it seems to be used successfully by collectors of woodworking planes. I know everyone here likes oxalic acid. I do, too. I've also used it with good results, but I'm just uneasy about its toxicity, especially when it comes to mixing up enough of it to dip a frame--I don't like the idea of dumping 75 gallons of it onto the ground or into my septic system. I'd much rather use something like citric acid, which as I understand it is essentially non-toxic (I know, I know, EVERYTHING is toxic if you ingest enough of it) and perhaps cheap enough to use in quantity. I'd considered regular household white vinegar--5% acetic acid--which seems to work (I've successfully cleaned small parts with it), but I can't see myself buying 50 gallons of the stuff at over a dollar a gallon, or whatever it costs. But citric acid looks like a good bet if it works and won't wreck paint. Anyone here tried it?
I apologize if I seem to be asking the same question over and over with different acids. It's just that I'm kinda nervous about dipping the Dawes Double Blue--beautiful bike, basically sound paint but pretty extensive surface rust. I don't want to screw it up.
JV

I've used both of these for rust removal...

Oxalic Acid - pretty safe to use with a light concentration.
Lye (sodium hydroxide) - removes paint, and will dissolve aluminum too (and your skin + bones...).

I use it a lot at work to remove rust from rusted Machine parts. The chemical plant rusts everything.
It leaves a Black Finish on some parts.
This Black layer can be wiped away.
I always soak the part in a secondary bath of Sodium Biarbonate (Baking Soda) to nuetralize the acid out of the pores and prevent later rust

if you're worried about toxicity why not try blackstrap molasses? People claim it works and it would be cheaper than citric acid crystals.

I have seen acetic acid (vinegar) used with some really impressive results. Maybe you could give that a shot.

oops, I see you tried acetic acid.

I soaked this frame in oxalic acid for 1.5 days if that helps:
http://farm4.static.flickr.com/3383/...ba0b62e4_o.jpg

http://farm4.static.flickr.com/3106/...277b1c5a_o.jpg

Blackstrap molasses does work, and very well--I cleaned some bolts and brake parts with it not long ago. As I recall from a web site posting on the subject, though, it's thought to be destructive to brass--not a good idea with a brazed frame. You wouldn't think molasses would eat brass, but maybe it does. I don't think I want to find out.
JV

well that's a good warning to heed, thanks. I think I'm going to have to run a scientific test of it and find out for sure.

secret formula rust remover
 

Use a 50/50 mixture of Iodine and mineral oil, An old time boatwright told me this ... It works!

I may give mineral oil and iodine a try on a few bolts or something. But I can't see mixing up 50 gallons of it to dip a frame--it would be cheaper to buy a new bike.
That's what I find potentially appealing about citric acid--cheap in bulk (like oxalic acid) but without the toxicity. Just not sure how well it works. I'll report back if I give it a try. That won't be until Vermont warms above the freezing point--early May, probably.
jv

Vinegar is my favourite rust remover it works very well, make sure the parts are degreased before putting in the vinegar. what I like about this method is that it works but is also very mild with no chance of damage, you can leave parts in as long as you like, just keep checking, if there is any rust left just leave it in a while longer.

385xza

Do you use straight out-of-the-bottle vinegar and generally how long does it take to work?

Yes, straight out of the bottle is fine, lightly rusted parts only take a couple of hours soaking. I usually dump bits in the vinegar during strip-down (remove grease first) and just leave the parts in for as long as it takes while I get on with other stuff. I have never had any parts damaged by leaving in to long.... some bits have soaked for a week or more with no harm.
385xza