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Sandblasting + Powdercoating - How to make sure stamped VIN on BB is still legible?

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Sandblasting + Powdercoating - How to make sure stamped VIN on BB is still legible?

Old 08-10-15, 09:04 PM
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billytwosheds 
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Sandblasting + Powdercoating - How to make sure stamped VIN on BB is still legible?

Hi all-

I'm in the process of restoring an 80's 3Rensho road frame that has taken on some rust damage. The paint is already bubbling in some areas, pitting in others. I'm planning on having it sand/beadblasted, cleaned of rust, and then powdercoated.

My question is: How can I maintain the VIN number stamped into the bottom bracket?

The rust is pretty bad down there, but I'm a little concerned that the above process(es) will more or less remove the VIN stamp. A thicker powdercoat layer seems like it would fill in the VIN stamp.

Can I mask off that portion of the BB and then paint it by hand after the other work is done? I don't mind a slight color difference, but it would be nice to hold onto that VIN. Or is there another method I should attempt?

Thanks a mucho
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Old 08-10-15, 10:12 PM
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Well first remember that the serial number isn't a VIN. There's no bureaucratic recording with the government or insurance companies of this number. One can stamp whatever word or number they wish and state on any bike registration form, invoice or police report that this is the ID for the bike.

Second why don't you ask your painter their method of saving surface detail? If they have no answer or don't seem to offer any indication of concern then maybe that's an indication of their skill or motivation. perhaps moving onto another painter is indicated...

Third there are masking methods available. But since I don't have my frames powder coated (I like detail to be preserved) I can't say much more. Andy.
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Old 08-10-15, 10:40 PM
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Thanks for the reply, Andy.

Originally Posted by Andrew R Stewart View Post
Well first remember that the serial number isn't a VIN. There's no bureaucratic recording with the government or insurance companies of this number. One can stamp whatever word or number they wish and state on any bike registration form, invoice or police report that this is the ID for the bike.
Ah yes, my mistake. FWIW serial numbers on bicycles are taken much more seriously here in Hawaii than other places I've lived...they actually require all bicycles ridden on the street here to be registered with the serial number and a DMV-issued bicycle ID number. The system is far from perfect, but it's one way they try to crack down on bicycle theft, which is rampant here. I meant serial number, but said "VIN".

Originally Posted by Andrew R Stewart View Post
Second why don't you ask your painter their method of saving surface detail? If they have no answer or don't seem to offer any indication of concern then maybe that's an indication of their skill or motivation. perhaps moving onto another painter is indicated...
Good point, something I'll inquire about with the painter.

Originally Posted by Andrew R Stewart View Post
Third there are masking methods available. But since I don't have my frames powder coated (I like detail to be preserved) I can't say much more. Andy.
The preservation of detail is somewhat important, as the frame has decent lugs and the "3RENSHO" embossed on the rear triangle. I'll definitely consider this.

Again, appreciate the reply. Mahalos
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Old 08-10-15, 10:43 PM
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sandblasting is unlikely to be a problem. A good powdercoat really isn't so thick as to obscure a properly embossed serial number, but some of them were pretty weak to start with. Telling the powdercoat guy to go a little thin on the area of the number will probably be enough. I suppose there are ways to improve the number, but they would be a lot of work.
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Old 08-10-15, 10:48 PM
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I had my frameset repainted (primer, 2 coats of wet paint, then clearcoat) and the paint filled the serial number so that it was illegible after painting. I used Jasco paint remover just on the serial number stamped into the bottom bracket shell, then hand painted the area using a small hobby brush and Testors enamel model paint which closely matched the paint color. It's a little sloppy, but the number is legible now and protected by paint.



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Old 08-10-15, 11:07 PM
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Originally Posted by Scooper View Post
I had my frameset repainted (primer, 2 coats of wet paint, then clearcoat) and the paint filled the serial number so that it was illegible after painting. I used Jasco paint remover just on the serial number stamped into the bottom bracket shell, then hand painted the area using a small hobby brush and Testors enamel model paint which closely matched the paint color. It's a little sloppy, but the number is legible now and protected by paint.
Ah, that's exactly what I was looking for! Thanks Stan.

Would paint remover have any impact on powdercoat, though? I suppose I could wear down the powdercoat using a physically abrasive means, but am not sure about a chemical agent that would have the same effect.
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Old 08-11-15, 07:15 AM
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If paint is to be removed to expose the serial number I would suggest a mechanical method. I'd probably use a sharp knife or an Xacto to scrape under/through the paint. For such a localized removal getting into the possible issues of chemicals isn't worth it to me. Maybe experiment on the OEM paint before the bike is prepped for refinishing just so you have a better idea of what this project entails. Andy.
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Old 08-11-15, 08:49 AM
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In my experience, chemical paint stripper may be used without any damage to the surrounding paint, powder coat, or base metal if you're careful to keep it localized to the small area of the serial number and then thoroughly clean the area with soap and flush with lots of water after removing the paint. I did have to use an Exacto knife to get the paint out of the stamping crevices.

Eric is probably right by suggesting you ask the powdercoater to simply make the coating thinner on the bottom of the BB bracket. It would be much simpler and cleaner than having to do what I did after the fact.
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Old 08-11-15, 12:24 PM
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rather than you, DIY before hand,
Ask them mask it off before blasting clean, then leave it bare when powder coated , apply touch up paint when finished .
same powder mixed in clear lacquer should do. & match.

Last edited by fietsbob; 08-11-15 at 12:29 PM.
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Old 10-20-21, 06:35 AM
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Hello to Scooper! Looking at your pics w/the red bottom bracket, what bike is this? I'm trying to identify a frame. Thanks!
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Old 10-20-21, 12:50 PM
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Originally Posted by steadyturtle View Post
Hello to Scooper! Looking at your pics w/the red bottom bracket, what bike is this? I'm trying to identify a frame. Thanks!
I haven't seen Scooper around here for a couple years, but knowing his long history with Schwinns, and looking at the section in the Waterford site where Paramount serial numbers are decoded I'm pretty sure it's 1987 Schwinn Paramount.

Further help with frame identity maybe forthcoming if you post a couple photos to the Classic & Vintage forum.
Brent
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Old 10-21-21, 06:21 AM
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thanks for your response. I cannot post photos until I have 10 posts or more.
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Old 10-21-21, 06:29 AM
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welcome to the forum, upload your pictures to an album in your gallery and we can rescue them for you
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Old 10-21-21, 06:51 AM
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Have the powder-coater mask it off, and just have him run a clearcoat on that section afterwards.
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Old 10-21-21, 07:19 AM
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I posted a few pics to the gallery album

Mystery Steel Bike 2021-10-21 09:17:40.

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Old 10-21-21, 09:42 AM
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Picture rescue


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