Bicycle Mechanics - Removing surface rust from a raw steel frame
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12-30-10, 05:01 PM
I recently purchased a raw steel frame with a bit of surface rust distributed across the frame. How should I go about removing the rust? Here are some ideas I came up with (but haven't tried yet):
- Scotchbrite pad
- steel wool 0000 or 000
- sandpaper 1000+ grit
Media blasting (glass beads, walnut shells, e.g.) works great. All of the abrasives you mention are too fine. If the rust is really light, 0 or 00 steel wool works OK, as does 400 sandpaper, but media blasting is the way to go. Sandblasting, however is too rough.
12-30-10, 08:44 PM
oxalic acid. search the classic & vintage forums for more info.
12-30-10, 08:56 PM
all the above methods would work.
you could also try a wire wheel + handheld drill
12-30-10, 09:27 PM
What ever you do plan on getting it painted or powder coated right away. Otherwise you may as well just leave it in a dry place until you're ready to actually get it coated with something that'll seal it.
12-30-10, 10:45 PM
The person I bought it from said he had been using carnauba wax to protect it for 2 years. It looks to have done a passable job, as there is only minor surface rust. I need to wait until the summer until I get it powder coated.
I think I will try the sandpaper first, as it is readily available in my home.
Remove all traces of the wax chemically before sanding or you will
have problems with the paint sticking.
12-31-10, 07:27 AM
Whatever removal process you use, the surface will need something to seal it right away (as been pointed out already) to keep it from rusting again. If it is light rust, you could use one of the spray converters on the surface. It will turn it black (oxide). I like the Rustoleum paints that have the converter in the formulation.
Are you planning on power coat, paint, chrome, or plain?
12-31-10, 09:48 AM
What do I use to remove the wax?
I tried a bit of 400 grit under the BB last night to see the results, and it left more scratches than I prefer.
The ultimate goal is to powder coat it, preferably clear, but that will have to wait until the summer.
12-31-10, 10:56 AM
Go to your local home improvement center and buy a plastic pad that is called "steel wool substitute". Squirt on a little WD40 and the rust will come off quite easily. Wipe it down with WD40 every week until you are ready to paint it, then wipe it with paint thinner to remove the last of the WD40.
White vinegar is great at removing rust. It's cheap and non toxic. Soak rags or old towels in the vinegar ,wrap up the frame and leave overnight.
12-31-10, 12:50 PM
At Trek we used a hot phosphoric acid bath on bare frames. Phosphoric acid was particularly suited for that purpose as it dissolves rust much more rapidly than it does the base metal and it simultaneously etched the surface to provide an ideal bonding surface for paint. A hot phosphoric acid bath might not be practical in your home, but consumer products such as "Naval Jelly" also contain phosphoric acid as the active ingredient and may suit your needs.
N.B. I had this bare steel fixture dipped in the phosphoric acid bath at Trek about 25 years ago, and it's lived in my damp basement ever since. It's held up pretty well:
12-31-10, 11:27 PM
Does anyone have tips on removing the wax? Would I still need to remove the wax if I use a "chemical" method rather than the "elbow grease" methods?
Right now, I'm leaning more towards a "chemical" removal process. It seems like the easiest way to remove the rust without marring the steel surface too much. As I said before, the 400 grit I tried last night left more scratches than I wanted.
White vinegar, WD40, and naval jelly all look pretty easy and fairly accesible. Has anyone tried the baking soda + water paste suggested here (I don't know about the credibility of this site...)?
After I remove the surface rust and get the frame all purtied up, I'm going to throw on a couple coats of wax to keep it sealed until I get it powdercoated.
Sorry for all the questions, guys. I just don't want to mess up this awesome new (to me) frame! It's a TET frame, btw.
I don't know if I would use baking soda and WATER. I think that water is something you want to avoid.
There are commercial wax removers available. Ask your local autobody shop what they use to remove wax and grease prior to painting. I think it was called " Prep Sol" or something like that.
Why don't you wait until you are ready to paint before removing the rust and avoid the wax?
You could store the frame in a plastic bag with some silica gel to avoid further contact with moisture until ready.
01-01-11, 12:05 PM
I would like to ride this bike in nice weather until I'm ready to get it painted. I don't mind the elbow grease.
I guess I'll just head to a local auto shop and ask them what they have. I have read that denatured alcohol will work. Any experience? I have some laying around from an old project.
01-01-11, 01:44 PM
At Trek we used a hot phosphoric acid bath on bare frames. Phosphoric acid was particularly suited for that purpose as it dissolves rust much more rapidly than it does the base metal and it simultaneously etched the surface to provide an ideal bonding surface for paint. A hot phosphoric acid bath might not be practical in your home, but consumer products such as "Naval Jelly" also contain phosphoric acid as the active ingredient and may suit your needs.Naval Jelly is the way to go. It preferentially dissolves rust faster than the bare metal underneath. The other acids will eat up the good metal just as quickly once it gets past the rust, not a good thing.
oxalic acid. search the classic & vintage forums for more info.Sure, you can also use an 80-grit pad on a high-RPM grinder to remove paint from the frame as well. But the results won't be as nice or optimal as using a chemical paint-stripper. Who cares about a couple of holes in the tubing, the paint & rust is gone right?
01-01-11, 02:42 PM
Here's an example of the rust. It's very light, and there are similar sized patches of this spread around the frame.
I never could get enough jelly out of my naval to do a job that big.
01-03-11, 07:35 PM
I picked up some Naval Jelly today and spent the rest of the day getting the rust off. The instructions on the bottle say to rinse off the jelly with fresh water. I used a bucket of water and some wet rags to wipe off the jelly, dried off the frame, and then went over it again with another wet rag.
Is this enough to "neutralize" the acid? It's been a couple hours and the frame has been coated once with carnauba wax. If the acid wasn't neutralized or diluted, will there be long term effects on the steel? Am I being paranoid, or should I go back and use more water?
01-04-11, 12:06 PM
The double-wipe with wet rags is fine for cleaning as long as you don't leave it standing on the bare metal. The Navel Jelly also leaves a layer of iron-phosphate which serves to protect the surface somewhat. It's only temporary and you should follow up with some other coating soon after.
01-04-11, 01:03 PM
I wiped with a wet rag, dried with another rag. When I finished the whole frame, I rewiped the whole frame down and dried it off. I've since wiped on a layer of carnauba wax, and will recoat a few times over the next few days.
01-04-11, 03:42 PM
On bare steel frames, I've had good luck with clear polyurethane or epoxy paints (the 2-part mixed auto paints). They don't yellow over time like the acrylic or enamel clears you get in the rattle-cans. Also sticks to bare metal well, although not as well as primered metal.
01-04-11, 10:21 PM
Wax will work but you'll need to apply it fairly frequently. If you want the bare metal look you're far better off to go for the stuff Danno mentioned above. Or possibly go for a clear powder coat. Or apparently you have the option of tinting a clear powder coating as well so it has a transparent look to it. If you opt for a clear coating be sure to tell the finisher that you applied a number of coats of car wax. Otherwise it can mess things up really badly.
If you go for clear or transparent tinted PC then burnishing the metal with a funky brushed pattern using a medium to coarse metal prep disc could add a big heap of appeal to a "raw" metal finish. In fact you're giving me ideas for doing my old Miyata frame that needs re-finishing.
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