# carbon painting... primer ?



## eric_syd (Nov 10, 2005)

I bougth a carbon frame and I want to paint it.
First I need to sand it but do I need to use a primer ?
I thought the primer was used to a interface with the metal.
Second question which will be common to all painting.
I'm going to use rattle can paint. Do I need to sand between layers ?


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## flynfrog (Feb 4, 2011)

Sand it with 240 grit shoot it with a high build filler primer. The longer you can let this cure the better. It will shrink as it cures revealing you weave under the paint. Wet sand your primer with 400-600 grit use a guide coat. if you are rattling it it just shoot a few wet coats and leave it at that.


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## eric_syd (Nov 10, 2005)

flynfrog said:


> Sand it with 240 grit shoot it with a high build filler primer. The longer you can let this cure the better. It will shrink as it cures revealing you weave under the paint. Wet sand your primer with 400-600 grit use a guide coat. if you are rattling it it just shoot a few wet coats and leave it at that.


Thanks for your help Flynfrog.


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## dbohemian (Mar 25, 2007)

Actually you may not need a primer, especially a high build type.

Most carbon frames are finished with a clear coat from the factory so you should sand this down to get your next coats to bond. 

Like a lot of things it depends on what you want to do. If you want to cover a lot of stuff you should use an epoxy primer (i.e. the composite is epoxy and carbon) so you will get great adhesion this way. If you want to maintain the carbon look, just sand with 320-800 depending on whether you are shooting solids, pearls or metallics. Shoot color, clear again and you should be good to go.

Painting bicycles could be a forum in and of itself. The techniques are quite varied and the raw materials can be very expensive. Often, like many things it may be cheaper to have a pro do it.


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## eric_syd (Nov 10, 2005)

Thanks Dbohemian,
I thought the same initially and that's why I started this thread. The frame is clear-coated so the fine sanding should make the surface quite smooth. I'm actually more concerned by the ability of the painting to "cover" the black colour of the carbon and to adhere to the epoxy.
I've made multiple carbon-kevlar=epoxy windsurf boards decades ago but I was clear-coating them with resin only.


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## TrailMaker (Sep 16, 2007)

Hey;

Paint is more "brittle" than primer, and does not adhere to hard surfaces that well. Speaking of catalyzed urethane enamel, the only bond it will generally obtain to harder surfaces is mechanical, gained from sanding and roughing the parent surface. The rougher the surface, the better the adhesion. However, this obviously comes at the expense of surface quality of the final finish. Primer is more "flexible" and porous and gives a better "open" surface for the paint to bite into, like a sponge. The bond is still essentially mechanical unless the paint is sprayed while the primer is still, to some extent, "green."

There are vast differences in the properties of spray paint, but in general you won't gain a lot by trying to put too fine a point on it. If you want great paint, there's only one way, and that is all in. Rattle can, not so much. It may give you a good "ten foot finish" but it won't likely look as good as real paint. The rule of thumb regarding any finish is use as little material as possible to create the desired look, especially on the substrate. The more material there is, especially the "soft" primer, the easier it will chip and flake off. For what it is worth, although the color selection is extremely limited, about the toughest rattle can paint I have found is WalMart branded stuff. It sticks so well to sanded bare metal that I have to mechanically remove it with a scuff pad and thinner, and it takes a good while at that. it is very easy to spray and covers very quickly. The opposite end of that spectrum is Krylon, which scratches VERY easily, liquefies immediately with just a rag and thinner, is very thin and runny, and scratches very easily.


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## Sagnak (Jan 26, 2012)

eric_syd said:


> I bougth a carbon frame and I want to paint it.
> First I need to sand it but do I need to use a primer ?
> I thought the primer was used to a interface with the metal.
> Second question which will be common to all painting.
> I'm going to use rattle can paint. Do I need to sand between layers ?


Yes you need primer as it holds the frame and paint together and paint itself wont hold frame well it will come of.

well dont use those as they are not the best quality paint around use any acrylic car paint and if you need better quality and scratch resistance get AwlGRIP polyurethane paint.:thumbsup:


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