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Old 08-11-10, 09:42 AM   #1
ClarkinHawaii 
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clearcoating raw carbon fork

Recently I ordered an extra carbon fork from the factory in China. I don't really know if it's going to be clearcoated or not.

If not, what's the best way for me to apply a clear finish? I don't have a dust-free indoor paintroom nor do I have spray equipment. So if I'm going to spray, it has to be outdoors hanging from a tree

So there's probably a rattle-can clear paint. Is it possible to use a brush-on clear "paint" (lacquer?) of some kind, applying several layers with steelwool or such in between to give a nice deep glow? Perhaps rattle-canning just the top coat. I seem to lack the ability to spraypaint without runs.

What would the typical auto body shop charge for this service?
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Old 08-11-10, 09:57 AM   #2
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CF forks aren't really clear coated. Like fiberglass, the CF fibers are in an epoxy resin that will have a smooth, glossy finish. No need to do anything else unless you want to color them.
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Old 08-11-10, 10:11 AM   #3
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The clear coat on carbon is for more than just looks. It's there to provide a first line of defense from scratches and shallow dings that would otherwise cut into the carbon fibers themselves and compromise the fork's stregth. So if the fork you get is truly raw then you need to put something on there that has some significant thickness. Ideally that would be a thin coating of some epoxy resin that is resistant to scratches and dings to act as an armor coating. This can actually be done but it's a crap shoot when you don't know which resin was used for the carbon layup so that they would be compatible to get a good bond and to coat it evenly. All steps that sound a bit tough given your stated troubles and lack of gear.

So in this case I'd suggest using about 5 to 8 coats of an oil based polyurethane clear varnish. If you get the semi gloss version it'll give you the sort of matt sheen that it sounds like you're after. If it's too dull you can mix gloss and semi gloss to achieve whatever final look you want and since you need to build up the protective coating with multiple coats you have some room to experiment on the first coats to get the sheen just right.

Use an oil and wax autobody prep solvent to clean the carbon layup before applying the first coat and do not even touch the carbon or in between coats without wearing latex or nitrile disposable gloves from that point on until all the finishing is done. A good quality varnishing brush will do just fine for applying the varnish. Adding about 10% mineral spirits to the varnish to thin it will allow it flow out so it's smooth like glass. From there you just need to learn to brush properly. I'm sure there's some guides around on the net about varnishing boat wood "brightware". Look them up. In any event the key is to lay the varnish on and even it out and not to suds it up with excess vigorous brushing. Done right the results will look like they came from a spray gun handled by an expert. To deal with the inevitable dust spots wait for a couple of days before the last coat for the varnish to harden up well and then wet sand with 400 grit to remove the dust bumps and to lightly dull the rest of the varnish. Then lay on the final top coat in as dust free a location as you can.

Because you'll be brushing the varnish on you could actually clean up a room top to bottom in prep for this by wet toweling the wallsm ceiling and floor to remove all the dust. Wet rag the furniture or remove it as well. And obviously no rugs or stuffed furniture in the area. Wear freshly cleaned clothing and don't scratch your head... When in the room move slowly so you don't stir up the air. Do all that and you may well not need to deal with any dust or at least it'll be only a very few spots.

The varnish is going to take some time to dry to full hardness
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Old 08-11-10, 10:34 AM   #4
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Originally Posted by CACycling View Post
CF forks aren't really clear coated. Like fiberglass, the CF fibers are in an epoxy resin that will have a smooth, glossy finish. No need to do anything else unless you want to color them.
Exactly right.
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Old 08-11-10, 11:16 AM   #5
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Originally Posted by BCRider View Post
The clear coat on carbon is for more than just looks. It's there to provide a first line of defense from scratches and shallow dings that would otherwise cut into the carbon fibers themselves and compromise the fork's stregth. So if the fork you get is truly raw then you need to put something on there that has some significant thickness. Ideally that would be a thin coating of some epoxy resin that is resistant to scratches and dings to act as an armor coating. This can actually be done but it's a crap shoot when you don't know which resin was used for the carbon layup so that they would be compatible to get a good bond and to coat it evenly. All steps that sound a bit tough given your stated troubles and lack of gear.

So in this case I'd suggest using about 5 to 8 coats of an oil based polyurethane clear varnish. If you get the semi gloss version it'll give you the sort of matt sheen that it sounds like you're after. If it's too dull you can mix gloss and semi gloss to achieve whatever final look you want and since you need to build up the protective coating with multiple coats you have some room to experiment on the first coats to get the sheen just right.

Use an oil and wax autobody prep solvent to clean the carbon layup before applying the first coat and do not even touch the carbon or in between coats without wearing latex or nitrile disposable gloves from that point on until all the finishing is done. A good quality varnishing brush will do just fine for applying the varnish. Adding about 10% mineral spirits to the varnish to thin it will allow it flow out so it's smooth like glass. From there you just need to learn to brush properly. I'm sure there's some guides around on the net about varnishing boat wood "brightware". Look them up. In any event the key is to lay the varnish on and even it out and not to suds it up with excess vigorous brushing. Done right the results will look like they came from a spray gun handled by an expert. To deal with the inevitable dust spots wait for a couple of days before the last coat for the varnish to harden up well and then wet sand with 400 grit to remove the dust bumps and to lightly dull the rest of the varnish. Then lay on the final top coat in as dust free a location as you can.

Because you'll be brushing the varnish on you could actually clean up a room top to bottom in prep for this by wet toweling the wallsm ceiling and floor to remove all the dust. Wet rag the furniture or remove it as well. And obviously no rugs or stuffed furniture in the area. Wear freshly cleaned clothing and don't scratch your head... When in the room move slowly so you don't stir up the air. Do all that and you may well not need to deal with any dust or at least it'll be only a very few spots.

The varnish is going to take some time to dry to full hardness
Thorough, as always--Thanks! Strangely, after reading all this (especially the part about wet-towelling a room) my ambition seems to have been reduced somewhat.

For a $35 fork, I'm afraid I don't have the right attitude. Slap it on as is and forget it sounds pretty good to me. But it's valuable to know how to do it , for future use!

I just installed a Winwood carbon fork (with disc brake tabs) onto another bike; and the finish is, well, awesome. Nice to know I could do that if I had to!

What I should do is contact the factory (the order hasn't shipped yet) and ask them to slap on some sort of protective coating. But the language barrier is so annoying to deal with that I'd rather wet-towel a room with 12' ceilings than attempt to communicate further with them. Be interesting when it finally shows up--I just figured for $35 I couldn't go far wrong . . . Thanks again.
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Old 08-11-10, 01:56 PM   #6
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35 dollar fork???
You sure you can trust these CF forks on your bike??
They are cheap, but who knows if they are skimping on materials that you cannot see, to be able to sell it at such ridiculous prices?? Plus there most likely no company to go to if something goes wrong. Be careful!.....
JMOs

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Old 08-11-10, 02:14 PM   #7
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A buddy did a stint in USCG in their Helicopter maintainence , as the rotors are CF ,
part of the maintainence was filling in finish flaws with more Epoxy,
and Vacuum Bagging it to get all the air bubbles out of the epoxy before it cures.

as far as a $35 CF fork goes heck they may all start out that low, in Cost,
and branding and marketing and distribution + retail all add a layer..

thats why they go to China , race to the bottom..

I'll stick to Metal myself..
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Old 08-11-10, 02:20 PM   #8
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Add, : Not any bikes but, I own a Carbon Fiber Mandolin, It's top coating is Lacquered ..
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Old 08-11-10, 06:32 PM   #9
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Be careful!.....
JMOs

Chombi
Always smart advice. I'm also getting another of the $35 forks with a full-carbon bike attached. Presumably all of like quality. I'll make a fortune taking wagers over which part will be first to fail catastrophically and result in my death.

Actually I think it's the same fork you'd pay $200 for with a big name on it, maybe a nicer finish. Over at roadbikereview forums there is a huge thread (well, now 2 huge threads) about these frames. Guys have been buying them like hotcakes since last fall and nothing has failed yet. They convinced me.
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Old 08-22-10, 10:32 PM   #10
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$35 fork received--the finish is identical, right out of the box, to the Winwood $230 fork--When the poster commented on the ridiculous $35 price, I have to disagree--I think that the $230 price is the ridiculous one. Bottom line is it's beautiful and matches up perfectly with my new Ti frame.
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Old 08-23-10, 12:01 AM   #11
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I expect the marketing and distribution chain the Winwood passes thru adds costs at every step
Its what makes america great .. out source the work and make more money shipping it and promoting it.
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