Classic & Vintage - Powdercoat or clear finish?

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View Full Version : Powdercoat or clear finish?


Fidelista
03-02-09, 01:33 AM
I took my frame and fork to a chrome plater to have the fork chromed and the frame chemically stripped. The fork turned out well but the steel on the frame was discoloured and scratched from a wire brush, so I went to work on it with some abrasive paper.
Now I'm getting to the point where the bare (almost) polished steel is starting to look good. I've polished and flattened Plane irons and chisels by hand, so I know I can get a mirrored surface on it that would rival chrome. I don't think I want to go that far though. I would like the steel bits to look like steel, and the chrome to look like chrome. I also know that the more highly polished steel is, the more it shows rust.
So I'm thinking of clear powdercoating over the bare steel. I've searched some threads on powdercoating, and several people have mentioned rust appearing under the powdercoat. I suspect poor preparation is the culprit. I believe that I can get the frame clean enough that abrasive blasting is unnecessary, unless it's to key the surface. Obviously I will have to discus this with whichever powdercoater I choose.
Should I just spray some rattlecan auto clear on it, and see if it rusts? At least I can strip off the auto clear easier than stripping off p/coat.
And it's a nondescript (I assume) probably Taiwanese frame. Nice enough and light enough but no museum piece.
The serial numbers are on the bottom bracket :438283, Q9,4. Brazeons for 2 bidon carriers and shifters only, cast dropouts with screw adjusters. So should I just go straight to powdercoat, or try a clear sprayed finish first?


unterhausen
03-02-09, 08:36 AM
I wouldn't do it myself. I saw a bike made by Mike Appel where he had the same idea as you. He was obsessive, and polished his frame to a high shine. By the time the clear coat had cured, there was a spiderweb of rust underneath. It was beautiful, but I'm sure it eventually caused the clear coat to fall off.

If your powdercoater leaves pinholes or thin spots, there will be rust. Primer keeps that from happening.

Apparently there is a clear primer. Don't know anything about it.

Fidelista
03-02-09, 12:16 PM
I wouldn't do it myself. I saw a bike made by Mike Appel where he had the same idea as you. He was obsessive, and polished his frame to a high shine. By the time the clear coat had cured, there was a spiderweb of rust underneath. It was beautiful, but I'm sure it eventually caused the clear coat to fall off.

If your powdercoater leaves pinholes or thin spots, there will be rust. Primer keeps that from happening.

Apparently there is a clear primer. Don't know anything about it.I can't see the difference betwen a powdercoat with pigment and a powdercoat without, unless it's the primer.
If rust will occur under clearcoat, what stops rust when the frame is painted or powdercoated with a pigmented?
I've seen powdercoated steel that was continually immersed in salt water for a year. Not a trace of rust.


Oldpeddaller
03-02-09, 02:06 PM
I can't see the difference betwen a powdercoat with pigment and a powdercoat without, unless it's the primer.
If rust will occur under clearcoat, what stops rust when the frame is painted or powdercoated with a pigmented?
I've seen powdercoated steel that was continually immersed in salt water for a year. Not a trace of rust.

Continually immersed in seawater, I'd believe it.

But if used in a coastal atmosphere, rather than submerged without air, it'll rust - steel rusts, even stainless steel, aluminium goes crusty and crumbles, galvanising peels and brass loses its copper and goes weak. I work in a port environment and see high quality powder coated equipment cabinets flaking and bubbling from rust under the coating in around eight months from new. It's not just the salt in the air - acids from thousands of truck exhausts per day, chalk dust from the "White Cliffs" and heaven knows what from the ships funnels create an always damp corrosive miasma. A GOOD paint system, regularly checked and touched in - or fibreglass instead where possible, seems to be the only answer. Hopefully the OP doesn't live in this type of atmosphere, because his idea sounds stunning!

Banzai
03-02-09, 02:11 PM
I wonder if there's a framesaver equivalent for aluminum, or if it's necessary?

unterhausen
03-02-09, 06:31 PM
Seems like Rivendell has done this with at least one of their frames, but they didn't even bother to clean all the carbon cruft off of the frame. Some people like it. I had to work hard not to be embarrassed for the framebuilding community. I have thought of doing this to an all stainless frame. Not too many vintage frames that can withstand this kind of scrutiny.

Fidelista
03-02-09, 07:35 PM
Continually immersed in seawater, I'd believe it.

But if used in a coastal atmosphere, rather than submerged without air, it'll rust - steel rusts, even stainless steel, aluminium goes crusty and crumbles, galvanising peels and brass loses its copper and goes weak. I work in a port environment and see high quality powder coated equipment cabinets flaking and bubbling from rust under the coating in around eight months from new. It's not just the salt in the air - acids from thousands of truck exhausts per day, chalk dust from the "White Cliffs" and heaven knows what from the ships funnels create an always damp corrosive miasma. A GOOD paint system, regularly checked and touched in - or fibreglass instead where possible, seems to be the only answer. Hopefully the OP doesn't live in this type of atmosphere, because his idea sounds stunning!Actually, I can see Sydney Harbour from my window.
I don't plan to ever ride the bike in the rain, or leave it outside. I have other bikes for that.
I used to be shipwright, and I worked on more than a few old wooden boats. I've seen thick stainless bolts fall apart with only a few months exposure. OTOH, the powdercoated railings at my sailing club are constantly bathed in salt spray and look like new, 8 years later. It's only a gut instinct ATM, but I can't help feeling that it comes down to preparation and as Unterhausen said...primer.
I can say I have a new appreciation for the work necessary for chrome plating now!
I'll be seeing the powdercoater this afternoon. I won't proceed unless I am completely

unterhausen
03-02-09, 08:07 PM
nothing bad is going to happen, so go for it. My thought is that they are going to want to media blast the frame, in which case I don't see the value in doing this. If you can get them to clear coat a polished frame and it works, you'll be a hero.

Fidelista
03-03-09, 12:46 PM
http://s173.photobucket.com/albums/w42/stevebaby_photos/?action=view&current=100_0202.jpg
http://s173.photobucket.com/albums/w42/stevebaby_photos/?action=view&current=100_0204.jpg
There is no need to remind me what a crap photographer I am.

squirtdad
03-03-09, 01:07 PM
[QUOTE=Fidelista;8461054There is no need to remind me what a crap photographer I am.[/QUOTE]

if you use the IMG options in photobucket then it will display in your post when you paste it

Fidelista
03-03-09, 01:32 PM
if you use the IMG options in photobucket then it will display in your post when you paste itFor some reason the IMG options don't come up, just on those two pics.

squirtdad
03-03-09, 02:28 PM
as noted by unterhausen...Rivendell uses clear coat over steel on some bikes. I think it is a love it/hate it type of finish

My assumption is that if there were potential rust issues they wouldn't use this option.

Afaik powder coat does not use "primer" like paint does....the coat is the the coat, clear or not.....

anyway here is a link to a pic it feels kinda of a steampunk finish

http://www.rivbike.com/products/list/bicycle_models#product=50-640

Grand Bois
03-03-09, 06:04 PM
There's a cleared Bombadil on the Rivendell site. It wasn't polished prior to applying the clear powdercoat, but it certainly wasn't blasted either. I like the look.

Fidelista
03-04-09, 12:13 AM
I spoke to the powdercoater today. My first question was "Is this possible" and he said yes of course. He seemed surprised that I would ask. When I asked about rust under the coating he told me that if it isn't rusted when it gets coated then it shouldn't rust on a bike frame.
I have to do the prep, which suits me actually.
I'll sand some more to get a fine brushed look I've been spraying WD40 on it after every sanding session. I'll deliver it with the WD40 on the frame and they will clean it off with a solvent.
The Rivendell link was quite encouraging. Thanks for that.:)

squirtdad
03-04-09, 02:57 PM
Waiting for pics when it it done :)