is it feasible to paint an aluminum bike by slightly sanding it and painting over it?

I'm looking to paint an aluminum bike and as i've read about it it seems that i need to chemically treat aluminum before painting.I would therefore like to ask if it's possible to just rough up the current paint and paint over it, as the current paint is in good shape.
I have access to basic tools and possibly a compressor/spraypaint setup.
thank you for your help

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canucksgirl5 years ago
Aluminum is trickier to paint. If you want the new paint to adhere and last, you need to sand it, AND apply an aluminum oxide primer. Then make sure the paint you use is also formulated for aluminum surfaces, otherwise you're going to end up wasting your time and materials. Without the primer, the paint may not even stick, and if it does, it won't last.
matosmeister (author)  canucksgirl5 years ago
that was exactly what i was trying to avoid, hence the idea of sanding a bit of paint so that the new one can get a hold.
I understand exactly what you are trying to do, however, I can tell you from a ton of experience that you won't be happy with the result. It is virtually impossible for you to know the precise paint formula that was used on the bike previously, and if the new paint is incompatible (which it more than likely will be), it will go on unevenly and will chip and peel off. That's just a reality, and that's why you should sand to metal, prime and then paint.

You do have another option (if the labor is what you are trying to avoid), and that's contacting a powder coater. They should be able to do all the prep work, sanding, priming and painting for under $100. You'll just be responsible for disassembly and reassembly.

At the end of the day, its your choice what you want to do. I'm just not going to lie to you and tell you what you'd like to hear.
matosmeister (author)  canucksgirl5 years ago
Nah, I'm not scared of the labor part, I'd say It's more of a availability issue, where I live it's hard enough buying half-decent regular spraypaint, it would be almost impossible to purchase aluminum-specific paints and primers, at least without going through every hardware/paint shop in the area explaining very tediously what I want to buy from them. I guess I'm postponing the whole thing,since it was more of an aesthetic matter than a functional one. Anyway thank you very much for the insight and for the time.
I've re-painted a dozen or more bicycle frames, a couple of motorcycle frames and a kiddies backyard swing-set, all without totally removing the existing paint and never once had an issue with paint compatibility. As long as the paint job on the bike frame is old or baked on and completely cured I sincerely doubt you'll have a problem.
If you want to be absolutely sure, spray a small test patch under the crank housing and see for certain.
As I said before, thoroughly rough the existing paint with sandpaper and make sure it is scrupulously clean. Apply several coats of a high quality paint, (cheap paint begets a cheap paint job; auto parts stores are a good source for high grade paint) and I doubt you'll ever have a problem. But test it first, just to ease your concerns.
matosmeister (author)  Burf5 years ago
I decided to try my "theory" on a piece of another frame i have lying around that's already cut up for pieces, no harm in ruining that paint if it goes wrong. thanks for the advice, when I get to it (probably in the summer) I'll try to remember to post results.
You could always try an auto-body or motorcycle shop. They'll either have the materials you need on hand or should be able to get you the materials at cost. And it doesn't hurt to ask. (I grew up in a small town, and so I know how tough it can be to get things you need. Sometimes you have to get creative).
Burf5 years ago
So long as there are no bare spots in the current paint, you should have no problems painting over it. I'd recommend a light rub down with 220 grit sandpaper and then wash it thoroughly with a liquid dish washing detergent and rinse and dry well.
You'll have the best results if the color you're applying is a darker shade than the present color.
caarntedd Burf5 years ago
+1. If the old paint is sound you will be OK.
matosmeister (author)  Burf5 years ago
thank you very very much!
have a nice day sir
You're quite welcome.