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Old 09-17-11, 10:47 AM   #1
Gege-Bubu
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Partial painting : seat tube

I am going to replace my front derailleur, and I would like to take this occasion to touch up scratches on the seat tube made by old clamp.

The seat tube in area of the clamp is scrattched pretty bad.

Can just I use auto paint spray?
How I need to prepare a surface for painting?
Do I need to spray some kind of protective coat as well?
Can i prevent scratches ?


I understand that I need to isolate painting area and cover the bike all over, but what else I should do to make it a neat job?

Thanks!
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Old 09-17-11, 10:49 AM   #2
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Do you have a photo of the damage?
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Old 09-17-11, 11:05 AM   #3
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Do you have a photo of the damage?


IMAG0066 by Genna B, on Flickr
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Old 09-17-11, 11:11 AM   #4
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Are you looking to make the repair blend in or just cover it for protection?
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Old 09-17-11, 11:24 AM   #5
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Are you looking to make the repair blend in or just cover it for protection?
Just simple scratch cover, I don't care if color does not match precisely
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Old 09-17-11, 11:42 AM   #6
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Honestly . . . I'd just go to the hobby shop and buy a model paint in a jar that is a close match. If you reallt want to get fancy, buy red and yellow and start blending the two until you get the closest match.

Clean the area well with dishwashing soap and then a mild abrasive/polish that doesn't contain wax. Use a toothpick to fill in the scratches until they are level. Let dry and then use more polish to flatten it out. For protection I'd wrap the damage with clear adhesive vinyl used in making outdoor signs. That stuff is only a few thousandths thick, so it may still fit under the derailleur.

That's how I'd fix it, but there are probably a hundred different opinions on what is best.
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Old 09-17-11, 12:58 PM   #7
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Honestly . . . I'd just go to the hobby shop and buy a model paint in a jar that is a close match. If you reallt want to get fancy, buy red and yellow and start blending the two until you get the closest match.

Clean the area well with dishwashing soap and then a mild abrasive/polish that doesn't contain wax. Use a toothpick to fill in the scratches until they are level. Let dry and then use more polish to flatten it out. For protection I'd wrap the damage with clear adhesive vinyl used in making outdoor signs. That stuff is only a few thousandths thick, so it may still fit under the derailleur.

That's how I'd fix it, but there are probably a hundred different opinions on what is best.
Thanks! This is great information.

Can I ask you more questions:

1. Can I use carbon braze-on adapter on aluminum seat tube or it should be aluminum?

2. What adapter I should get: the one with long hole or just a circle hole?

3. if my seatpost is 31.6, what size the adapter should be: 32mm or 31.8mm?
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Old 09-17-11, 03:07 PM   #8
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Personally, I am a fan of using clear nail polish over scratches like these. The original scratch stands out a lot less than a mis-match paint touch-up.

Surprisingly, the polish provides a lot of protection too. I did one of my bikes two or three years ago and the original scratches show no sign of rust.

Always a good idea to wax the frame after the polish is dry.
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Old 09-17-11, 05:35 PM   #9
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Easy to fix...

Sand it a little bit to get the surface kind'a smooth with 400 sand paper, then apply car paint over it, I would get 1stage paint and if the color doesnt match what u can do is to use masking tape and create like a strip in black or white or something. With 1 stage paint you dont need to clear.

Good luck.
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