Classic & Vintage - Oxalic Acid Question
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10-17-08, 10:50 AM
I am going to soak a newly aquired frame this weekend. I have stripped just about everything off the frame but I have not removed the headtube races. Do I need to remove these? Will the Oxalic acid tarnish them. The headset is either an Athena or Chorus headset from the late 80s or ealy 90s.
I can't answer your question, although I can say it is very easy to get the headset cups out of the frame. If there is any question in your mind about the finish of the pieces, I would just remove them.
See $1 homemade tool here: http://davesbikeblog.blogspot.com/2007/06/headset-removal-and-replacement.html
10-17-08, 12:06 PM
Acid corrodes metals. It may well cause pits and discoloration in the races. I suggest removing same - it's quite easy. A bike shop, with proper tools, would be able to get them out in a flash.
When working with strong and poisonous acids like oxalic, be sure to wear gloves (neoprene - like what they sell for doing dishes) and protective eye-wear. No food or smoking near the acid. Wash thoroughly when finished. Don't let pets near the work area. If a cat gets some on their coat - then washes - you know the rest.
Isn't oxalic acid the acid that builds up in your muscles when you workout a lot, thus making you 'feel the burn'?
10-17-08, 12:19 PM
You are thinking of Lactic acid.
10-17-08, 12:45 PM
Oxalic acid doesn't hurt steel or chrome; it only reacts with the rust. However, who knows what it will do over the years if traces are left behind in tiny crevices between the races and head tube. Popping out the races is a routine bicycle maintenance task. Just make a tool like this from a piece of 3/4" pipe. The split ends are spread a little so they spring out to the diameter of the cups when the tool is pulled into the head tube backwards. Then just tap the race out. I added the cap for hammering.
right, lactic acid. thanks
10-17-08, 01:15 PM
How will you flush the solution out of the stays? Heck, how do you assure yourself it comes out of the main tubes?
Old Fat Guy
10-17-08, 01:26 PM
Why not just give it good treatment of frame saver?
Soak it in a baking soda bath to neutralize.
+1 Remove the headset, although I did not on the last bike I treated (I now have a headset tool kit). Acid will corrode aluminum, so if your headset is aluminum, it will affect it.
You should have a very dilute solution of oxalic for soaking.
From the vintage BMX site:
"Oxalic acid is typically marketed as a wood bleach in hardware stores. It costs less than 10 bucks. All you need to do is mix a few ounces of Oxalic acid in a large tub of water, and soak the parts for 12-36 hours. You simply wipe the parts free of the rust occasionally with a white (soft, non-abrasive) scotch-brite pad, and you are done.
Rinse the parts off, and coat the insides of the tubing with LPS-3 rust proofing. Done. On to polishing...
The pitting will never go away, but you have not added any steel wool scratches, or scotch brite scratches, or any other damage. In fact, it will often leave the decals in tact! Especially if you cover them with tape first!"
The only place I divert from this process is that I treat the inside of the frame with framesaver. I did not tape over any decals, and they were not affected, but your experience could vary...
10-17-08, 02:01 PM
For peace of mind, do remove the crown and head races. Just because oxalic acid doesn't specifically eat iron and chrome - doesn't mean Murphy's Law won't raise it's ugly head(s). As an organic chemist, I've seen the unexpected occur regardless of how carefully one establishes bullet-proof parameters of safety in a laboratory.
Personally, I'd find another way to do the job without using oxalic acid. The stuff is just plain nasty - from a chemical standpoint. Neutralizing the oxalic acid into sodium oxalate (using baking soda to neutralize) is an excellent idea. Just be sure to rinse with plenty of water and down a safe drain - sodium oxalate is almost as poisonous as the acid itself - it just lacks the corrosive characteristics.
10-17-08, 03:56 PM
Be very careful with aluminum around these acids and bases. Bare aluminum exposed to air protects itself by forming aluminum oxide on the surface. Acids can break down the aluminum oxide and then the bases used to neutralize the acids can really attack the bare aluminum, eroding it and turning it dull gray. If you get any rust treatment acid solution on your aluminum parts, rinse them well with water and set them aside to allow the aluminum oxide to reform on the surface. In general, it's best to keep your alloy parts well away from all bases, including laundry and automatic dishwasher detergents, which are pretty darn caustic.
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