Question about full frame OA baths...
 

All,

I'll hopefully soon be in possession of a frame that I'll want to do a full OA bath and Framesaver as a preventative measure. Two questions:

1) Assuming vessel of appropriate size and depth (kiddie pool type thing) how do you ensure getting the OA solution everywhere in the frame?
2) Once the OA bath is done, what's the procedure for getting all the bath out and the frame dry? Hair dryer(s) into the big tubes?

Oh, and just a tip for doing a fork only: a vessel that works famously if you only have to do a fork is a wallpaper water tray:

http://www.mastercraftmfgs.com/wt.jpg

They're just the right size and available in up to 30" lengths or so. And some are designed to be disposable and are therefore cheap and flimsy, but would last for several if not more fork baths.

My latest iteration is a fabricated wood box, lined with two layers of blue plastic tarp. The reason for the box is that it is smaller than the kiddie pool, so it takes up less room, and uses less OA.

Make sure all of your drain holes are open, its pretty obvious (pull up the frame, if solution doesn't start coming out a drain hole, its probably plugged.

I use compressed air to blow out the frame, after rinsing it with baking soda solution first. I reuse the OA solution many times. My current bath is on the seventh frame through it.

I use a similar small tub for forks to the one you posted.


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Interesting thanks, I think I remember seeing this a while back. Thanks for that. How much baking soda per gallon for the base wash?

Here's an idea, what about plugging up the holes and filling the frame with OA directly? Then treat anything on the outside of the frame directly? (Just came to me)

I made a similar temporary "tank" for a BMX frame, that's the only full frame I've soaked so far. I also added cardboard boxes underneath the plastic sheeting to fill the spaces between the main diamond and the stays, that way I was able to use less liquid (I used about 8 gallons.) I thought about using a small electric pump to keep the bath mixed and circulating, but I haven't got around to trying it out yet.

Thanks for the wallpaper tray suggestion, that looks like a great idea!

Edit - I see that I haven't directly answered the questions... I assume that submerging the frame would get all surfaces into contact with the OA, but in my case the frame only had rust on the outside (it was chrome.) I also used compressed air to speed the drying out process.

The amount of baking soda used really has absolutely nothing to do with the gallons of base wash. I do not neutralize the entire bath. I am only neutralizing the minimal amount of residual clinging to the frame. I take the frame out of the bath. Mix up a couple of gallons of baking soda in a bucket, use maybe 1/2 pound of baking soda. You can find baking soda at Walmart for about 50 cents a pound. Then I use a pitcher or similar to pour the solution through the tubes, and I use a rag that I dip in the baking soda solution, to wipe down the outside of the frame.

If I neutralized the entire bath, then I couldn't reuse it. OA is used as deck wash, applied directly to wooden decks. I've never seen anyone collect and neutralize that solution while washing their deck. And they use a heck of a lot more treating decks than you will use on a frameset. I apply the same logic to what I have in the OA bath when I am done with it.

I also use it very dilute, well under 1% solution.


Plugging up the vent holes to me is too much of a hassle, and on some frames, thats the only way the OA is going to get inside the tubes (particularly on forks and stays).

Yeah, you want the acid to circulate, not just sit still, pick the part out from time to time and let the acid drain and refill the tubes. Use a paint brush to swish around the rusty parts too.

I made a pool with a poly tarp and concrete blocks to hold up the sides, and when I was done with a bunch of parts and a frame, just drained it where it was. The grass didn't even wilt, so the acid must have been neutralized by the time I was done.

How come the mods haven't done a sticky for acid treatment posts?

all good tips.

agitation of the OA bath is a good idea and makes the process more efficient... a recirculating peristaltic pump would be ideal, but short of that, simply stirring up the water and lifting the frame out and dipping it back in periodically will also so the trick. and as wrk101 mentioned, don't plug up the vent holes! keeping them open is the only way to ensure that the acid can flow inside the tubing. and similarly, keeping them open will help the frame dry later. i try to position the frame at different angles during the drying process to assure that all the tubes have drained properly. they will dry much faster if they are fully drained first. the down tube, head tube and seat tube will drain the most easily and thoroughly. the top tube may not drain completely because the ends are flanged by the seat tube and head tube, and typically only have small vent holes at the ends. in that case, i will position the frame so that the top tube is perfectly vertical, to maximize drainage.

i like to use a toothbrush to brush the really scaly areas (such as inside the BB shell, typically) every few hours.

for neutralizing, don't neutralize the bath (again agreeing with wrk101). the acid is reusable. rather, transfer the frame from the OA bath to the baking soda bath... you really only need to neutralize the residual acid stuck to the frame.

for drying, you can use compressed air if you wish, but honestly, just letting the frame sit in the sun (or if in winter, above or next to your furnace or radiator) for a few hours is usually adequate.

Yeah, when I do small parts I just pull them out and brush them with a chip brush every once in a while it does help a lot. I also try to keep the vessel in a warm place too...I think the warmer solution is a tad more effective, if not quicker.

Thanks all for the tips, full frame makes a lot of sense now.

Is it really critical to neutralize the acid since in only reacts with rust and has little or no effect on clean steel?

Higher temperature makes the acid work better, also helps it dissolve much better.

I don't know about you all, but I've given up on OA for anything but large-scale soaks where the low cost makes it the best choice. For all my small stuff I'm sold on phosphoric acid: I find it works better, faster, and the "dark deposits" are either not a factor, or I can rub that off with a rag when still wet from the bath. OTOH, almost everything I've soaked in OA gets a light yellowish crust on it that does not rub off. If you have any tried-and-true tips for getting rid of the yellow, I'm all ears.

The phosphoric acid seems a bit strong and it discolors paint at full strength, do you dilute it?

To me, the yellow is all about concentration. Use it dilute, and don't leave it in for too long. I typically use it at around 0.4% or less, and leave it in for 24 hours or less.

yes, you should still neutralize the acid. from my understanding, any acid will accelerate corrosion of bare steel (when combined with moisture), but will dissolve rust at an even faster rate, netting you a clean steel layer. i tested this idea once by putting a rusty steel wool pad in OA. the next day, the rust was gone and the pad looked like new. i put it back in the OA and within a couple more days the pad had disintegrated into a fine sediment of steel dust.

I don't dilute it but don't put painted parts in (that I expect to keep the paint on). It does the job fast. I also make sure to get parts out before any harm might be done. Occasionally I've let it go too long and had parts develop a gray "crystalized" finish. Won't do that again, and I don't soak any hardened polished surfaces like bearing races/cups.