Sanding down to raw carbon

[Jacoo]

Ive got an old leggera carbon road bike and im in the process of building it up. Its not a bad looking frame, but the decals are just ruining it for me. The frame as visible carbon throughout, with leggera decals under the clear coat. I want to embark on the tedious journey of sanding through the clear coat to get the decals off, but im still hesitatant - i dont want to ruin it. I understand that if i sand through the top carbon layer it will look terrible and theres no going back from there.

So 2 questions. 1, has anyone here done this before and is it easy to accidentally sand too deep? And 2, do i absolutely need a new clear coat, or could i give it a wax coating with car wax every couple of weeks?

[Me rida my bicycle]

If you do it correctly you don't need new clear coat . But use smooth sanding paper start with 400 and move up to 1200. If doing it this way you can polish with normal car polish for a shiny finish. Have only done a bar and rear triangle never attempted a complete frame.

Edited March 7, 2019 by Me rida my bicycle

[Me rida my bicycle]

Here's the bar. Be warn there's no shortcut once you have started you have to be committed. You don't want to look at something you did not finish or have it resprayed.

[Jacoo]

That looks cool! Was that painted before or clear coat? Ive heard that carbon frames and parts that are painted over often have quite messy carbon weave since they dont care about how it looks under. That swirly look is nice though i like it. If i sand too deep in an area and expose the 2nd layer i might as well do it all over, create some patterns. But ideally i still want a nice even finish

[Me rida my bicycle]

It's quite easy to know if you are on carbon or clear coat when sanding. The carbon feels smooth and the clear coat feels "sticky".

Don't think you have to worry about going through the layers to much.

 

The bar was clear coated. For some reason clear coat and carbon never work it always starts to bubble or chip very easily especially if it's couple years old.

[Pulse]

Just keep in mind that most frames, especially the older designs have loads of fillers. Typically around the joints at the BB, Headset, etc.

 

You won’t be able to get a full exposed carbon look. As you sand away the paint in these areas you’ll end up at the black fillers.

 

You could have the centre sections of each tube exposed carbon, abd then repaint the joints.

 

Don’t worry too much about going into the carbon, you will see and feel the difference.

 

Also note that the older resins used are not UV stable, and if not protected by a UV protective layer will degrade and yellow over time with loads of sun exposure. There are many waxed that are UV protective, so not a big deal.

[Stall_Gear]

It's VERY easy to go a layer or 5 too deep, affecting structural strength!

 

From experience, I found wet sanding to have less of an impact on the carbon layers vs dry (and wet seems to be recommended by the experts anyway)

[Pulse]

It's VERY easy to go a layer or 5 too deep, affecting structural strength!

 

From experience, I found wet sanding to have less of an impact on the carbon layers vs dry (and wet seems to be recommended by the experts anyway)

Unless you are using a powered sander, using a fine grit sandpaper, I cannot see how one can go through several ‘layers’ of carbon without realising it

[Steven Knoetze (sk27)]

When the dust goes black you have gone too far.

I do a bit of carbon fibre skinning, seeing that black residue is heart breaking.......

[MrJacques]

Wear a mask / ventilator, you don't want to breathe in the particles, although, like Steven said, you shouldn't be sanding it down that much.

[Steven Knoetze (sk27)]

Wear a mask / ventilator, you don't want to breathe in the particles, although, like Steven said, you shouldn't be sanding it down that much.

 

100% agree on the mask, regardless of how much you will or won't be sanding..........

[JA-Q001]

You can also use a sharp Stanley knife blade and scrape the clear coat off. The carbon is a lot harder than the clear coat, so keeping the blade at a slight angle, you should be able to basically shave/chip the paint off. This works a lot faster than sanding. Then just finish with a very fine grit and check that you have a black residue evenly everywhere, then all clear coat is off.

[Pulse]

You can also use a sharp Stanley knife blade and scrape the clear coat off. The carbon is a lot harder than the clear coat, so keeping the blade at a slight angle, you should be able to basically shave/chip the paint off. This works a lot faster than sanding. Then just finish with a very fine grit and check that you have a black residue evenly everywhere, then all clear coat is off.

I agree with this, jist be careful at areas where joints have fillers. The fillers tend to be much softer than the carbon

[Goodbadugly]

When the dust goes black you have gone too far.

I do a bit of carbon fibre skinning, inhaling that black residue is health breaking.......

[WR 1.0]

Used a Stanley blade to first strip of the clearcoat. (slow and steady hands) Then switched to waterpaper sanding. Used this on a SRAM Red crank and a carbon handlebar.

[Skinnyone]

Sand it using wet paper....no dust to worry about - also results in a smoother finish.