I agree with Gene on both these counts. Let me expand a bit on why.
Wet paint uses both chemical and mechanical bonds to adhere to metal. These bonds are strong, and difficult for water and rust to penetrate and break. Rust from a scratch or chip does not spread easily. Prompt localized treatment and touch-up usually prevents further spread. Even if not treated, the rust will not spread across the surface. Usually it will dig deeper into the metal, but this is a much slower process, since the oxygen required is less available.
Powder coat, on the other hand, only encapsulates the part. There is no base primer to adhere to the metal. Anywhere there is an exposed edge (such as a threaded hole or at the head tube, seat tube and bottom bracket) water or oxygen can sneak in and start corrosion. Also, if any significant time passes between being blasted and being painted, rust can begin, especially in humid environments. Once started, it will spread easily across the surface of the metal under the powder coat as Gene described, and is impossible to stop. So it isn't a good long-term rust-preventive measure, but if you intend to use it as such, I suggest you have it done at a shop high in the dry air of the Rocky Mountains, and ask them to sprint from the blaster to the paint booth.
Greg Reiche CyclArt Vista, CA USA
-----Original Message----- From: classicrendezvous-bounces@bikelist.org [mailto:classicrendezvous-bounces@bikelist.org]On Behalf Of Eugene Powell Sent: Friday, August 08, 2008 9:59 AM To: Jon Spangler Cc: CR Subject: Re: [CR]Powder-coating and future restorations
Answer to the first question is, no you can go back and paint later. I've refinished many frames that had been previously powder coated.
As to the good and inexpensive part, I strongly disagree. Too many frames have come through my shop wrapped in powder coat and rusting away like crazy. One customer some years ago opted for clear powder coat only to watch his custom frame rust in just 3 weeks. 3 finishes in 2 years before he came to see me for paint. For a variety of environmental reasons powder coat is the future, but today it's not ready for prime time, and not good protection for your frame.
Gene Powell Rad Finishes Portland, Oregon USA
On Aug 8, 2008, at 12:31 AM, Jon Spangler wrote:
> Dear bikies,
>
> Does powder-coating a nice steel frame in any way limit or damage
> one's future chances of restoring its finish?
>
> My local bike shop's owner thinks that powder-coating is a good and
> inexpensive way to protect a steel frame, but I'm wondering whether
> the odds of a future restoration are compromised by this short-term
> protective measure.
>
> (I am not considering powder-coating as a long term measure or as an
> equivalent to a proper restoration repaint. Promise! :-)
>
> Thanks in advance,
>
> Jon Spangler
> Alameda, California USA
> hudsonspangler@earthlink.net
>
>
>
>
>
>
> _______________________________________________
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