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Frame restoration questions.(4 posts)

Frame restoration questions.the bull
Jun 29, 2003 4:02 AM
1.What is the best way to remove the old paint off a frame?
I would be tempted to sand it off, but would not be surprised if there is a substance I could use that would soften the old paint and disolve it off.Thoughts on sand blasting,would a steel frame get pit marks.
I only dread sanding all those nooks and corners.
2.Best paint to use.
I was thinking a PPG automotive paint.
Does spectrum charge a lot to paint a frame?
I love Indepent Fabrications as well but I dont want to spend a arm and leg here(If I can do it myself and get as good results).I have a air brush and a compressor.

Is there anyone out there with a restored Pre 1972 Colnago?
I woulds like to see pics of one that is "numbers matching"(Time correct)-Is that the right term?
I have restored some old muscle cars but this I feel is going to be more rewarding!
re: Frame restoration questions.M_Currie
Jun 29, 2003 7:00 AM
I've never done a bike, but I've done a few cars.

Sandblasting will roughen the surface a little, but if you use fine material it should be pretty smooth after priming. I've heard differing opinions on this for bikes. A sandblasted surface should take paint well. One bike shop guy I talked to recently about refinishing an old Cannondale said he's heard of good results from blasting with material that's been used once or twice already and lost some sharpness. Of course it's different with an aluminum frame, because you can blow a hole right through it. Steel should be easier. For the larger expanses of tubing you can always lightly sand after blasting to smooth it out a little.

If there are pitted rust spots, sandblasting is not always the best way to go, because it will not level the pitting, and may not penetrate into the bottoms of tiny rust pits. I've had some experience with this on car work, and found that even when a spot looks perfect, it will tend to rust faster after blasting than it will if you grind or sand it smooth. There is also sometimes a problem with sandblasting because the humidity in the compressed air makes the newly cleaned surface subject to almost instantaneous rust. Be ready to clean the fresh surface off immediately with appropriate solvent (Prep-sol or the like) and prime as soon as you possibly can. Make sure, too, that the air line has a moisture trap or filter when you hook up the sprayer/airbrush.

Of course you don't really need to remove all the paint where there is no rust. You can just sand the gloss off and consider it as primer.

It's challenging to get an even coating on tubing with a spray gun. If your airbrush is fairly high volume, you should be able to do it, but it will take a lot of coats and you may have to polish it to get a really good gloss. Automotive Acrylic enamel (can't remember the PPG name, but Dupont Centari is another) can look very good if it's well applied, but metallic finishes are very hard to get right. The particles tend to settle in the material if you spray too thickly, and even if the paint itself doesn't run, the particles will run and streak within it. You'd do well to find a junk frame and practice on that before tackling a valuable one.
Aircraft remover, available at Autopaint storesLone Gunman
Jun 29, 2003 3:38 PM
Just used some to strip off super thick paint of of a chrome fork. Spray it on let it work scrap it off, repeat as necessary.

Why mess with paint? Go powdercoat. Restored a '99 Lemond last year, PC, paint(2nd color), factory decals and clear. Granted I did not do the PC or paint work,but it looks great and is very durable. Currently redo is an '78 vintage frame, going with PC (Molteni orange or gloss black) and rattle can paint on the head and seat tube. Just rough up the spots where paint will be shot and apply.

Check classic rendevouz(sp) a classic bike website for pics of a '72 Colnago. I highly suspect that you will have trouble locating decals. No problem. Cycleart probably has them on file in his computer bank, however the only way you can get your hands on them is if he does the restore, fraud prevention I guess. Other painters have this service as well, expect to pay over $300 for a restore job.
I second Aircraft Remover...Dave Hickey
Jun 30, 2003 10:36 AM
I've stripped a couple of frames with Aircraft Remover. I bought mine at AutoZone. One word of caution: Wear gloves and a long sleeve shirt when using it. It's very strong stuff..