Advice needed re Rust

[Geoff]

I made an unwanted discovery the other day, today was the first time I was able to take a picture of it in daylight.

A bit of the powdercoat has flaked off my Kilauea just above the front mech band. Behind it is rust:





I don't really know if this is serious or not. A while back I was thinking of getting the frame resprayed but went off the idea. On the whole I think she still looks pretty tidy and I figured I didn't need to spend the money. However I went as far as getting some decals from Gil, (turns out I went off the colour of them- I made the wrong choice!). As an experiment I put a couple of them on the bike and I've noticed they tend to scratch and wear much faster than the main ones I have which are Kona originals. Gil has indicated they can be put under a liquid clearcoat which would be much better, but is it possible to put a liquid clear on top of a powdercoat? Obviously, I know nothing about bike finishes...

Do you think I need to respray it? I like how it looks now but there's not much point in having a frame I like the look of but which is rusting away to nowt underneath...

Rust and paint issues. Makes me want a Hei Hei... :roll:

 

[orange71]

can't see pictures?

 

[Geoff]

Strange. They're showing here. Linked in via Imageshack. Anybody else having problems?

 

[hamster]

This is the problem with powdercoat. It wraps the metal up like a plastic bag but the bond between the metal and the coating is poor. It takes a lot to break the coating, by then the rust is everywhere, as the damp just spreads under the coating. I guess that's why they don't powdercoat cars...

My Dawes tandem is the same, I'm going to get it refinished with a proper paint. While it does chip - powdercoat is really robust - it at least will stop rusting.

Nobody seems to use powdercoat in marine applications.

 

[Anthony]

This is the problem with powdercoat. It wraps the metal up like a plastic bag but the bond between the metal and the coating is poor. It takes a lot to break the coating, by then the rust is everywhere, as the damp just spreads under the coating. I guess that's why they don't powdercoat cars...
My Dawes tandem is the same, I'm going to get it refinished with a proper paint. While it does chip - powdercoat is really robust - it at least will stop rusting.
Nobody seems to use powdercoat in marine applications.

I see what you're saying, but if it's as bad as all that, how does it come about that powdercoating is the standard paint treatment for industrial plant that's left out in the open 24/7/12?

It looks to me as if the main problem here is that he-man Rymer has over-tightened his fm, as many he-men do, and made a crack in the paint, which has let in some moisture, with the result that you describe. That particular place is in many ways the most vulnerable part of the frame as it's the only place where anything is clamped around a piece of tubing 0.6mm thick.

I like to think this is just nature's subtle way of telling Geoff that a white 95 Kilauea should really have had 95 decals all along, even if they are a different colour from his favourite forks. And it doesn't pay to fight nature.

 

[Andy R]

Personally, I wouldn't worry about it over much. Remove the paint from the flaking area, treat it with Kurust or something, prime it and re-touch it.
Do the same with any other small areas you find. The front mech. clamp will have cracked the paint surface allowing moisture in.

If you're getting the whole frame repainted then it'll be media blasted before priming/painting anyway so that'll sort it all in one go.

It's the rust you can't see or get at that's more of a problem (like inside seat tubes) but it's not that common unless the seatube has no way of draining to the BB shell.

 

[Geoff]

I like to think this is just nature's subtle way of telling Geoff that a white 95 Kilauea should really have had 95 decals all along, even if they are a different colour from his favourite forks. And it doesn't pay to fight nature.

Smartarse!

Besides, I didn't get those decals to match the forks, I just asked Kona for some Kilauea decals and that's what showed up. This was back in 2000...

 

[hamster]

I see what you're saying, but if it's as bad as all that, how does it come about that powdercoating is the standard paint treatment for industrial plant that's left out in the open 24/7/12?

Because it's cheap and effective until the outer skin is damaged. Usually the sun degrades it and then it cracks and flakes after about 10 years.
When you also consider that it is on heavy duty steelwork, then limited surface rusting is no big problem. There's a big difference between a rolled steel joist and 0.6mm bike tube though.

 

[andrewl]

Geoff,

From the photo it looks like poor surface preparation prior to powdercoating is the biggest issue you have there - along with the band causing a break in the coat.

As a minimum put some auto rust converter on the mark to protect the metal. If you do decide to repaint in the future a wet spray will give a lot better an robust finish if done properly.

 

[Anthony]

I see what you're saying, but if it's as bad as all that, how does it come about that powdercoating is the standard paint treatment for industrial plant that's left out in the open 24/7/12?

Because it's cheap and effective until the outer skin is damaged. Usually the sun degrades it and then it cracks and flakes after about 10 years.
When you also consider that it is on heavy duty steelwork, then limited surface rusting is no big problem. There's a big difference between a rolled steel joist and 0.6mm bike tube though.

I understand that, but it still doesn't make me think that enamel is better for mountain bikes than powder.

I think there's a lot in what Andrew says, that you need to get the powder coater to put more care than usual into preparing the surface in order for powder coating to work on a bike, even if that makes the job slightly less cheap. The fact that the paint is very stiff and hard obviously means you need a very smooth surface for it to stick to. But if you achieve that and take care with the fm clamp, I don't see why powder shouldn't last a good long time, and in the meantime keep its looks better than enamel.