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polishing carbon fibre
RK - 12/1/13 at 06:37 PM

I have made a lot of carbon fibre pieces over the years, and I have a problem. They only polish up to a dull finish, even after polish, then wax. I am beside myself! I cannot get it to shine like you see on road cars.

This is what I have done:

sanded up through the grits to 2000
wiped on a layer of polish (autoglym).
waited til went dull
polished off with a rag
did the same with car wax.

NO improvement!!!

I have made every mistake there is in building my car, but this takes the cake as far as I'm concerned. I am seriously eyeing a track only Nissan Sentra race car to replace this. Total outlay would be ONE third of the cost of this.

[Edited on 12/1/13 by RK]

blakep82 - 12/1/13 at 06:50 PM

Description
Description
gave mine a coat of clear laquer

[Edited on 12/1/13 by blakep82]

snakebelly - 12/1/13 at 06:53 PM

Any pics? Sounds to me you might have sanded a bit too far in, do the parts have a clear gell coat or just bare resin parts? As already said you may have to lacquer to get the finish your after by the sounds of it

ashg - 12/1/13 at 07:01 PM

you ned farcela g3 and an electric polisher.

flibble - 12/1/13 at 07:17 PM

quote:

you ned farcela g3 and an electric polisher.

+1 Bit of warm soapy water and G3 worked for me

umgrybab - 12/1/13 at 07:32 PM

I think you're polishing way more than required. this could possibly become a problem in structural parts where you remove too much material. I've gotten perfect shine with only 300 grit but as above, clear coat or laquer is how you get it.

RK - 12/1/13 at 08:12 PM

When I recoat with resin, it comes out with little pits that I can't get rid of. I'm going to put another thin coat of resin on and call it a day (once I get the wax off). What is g3?

blakep82 - 12/1/13 at 08:22 PM

Not resin, but a can of laquer paint, thats what I did, sprayed it al over and it looks good

umgrybab - 12/1/13 at 08:26 PM

quote:
Originally posted by RK
When I recoat with resin, it comes out with little pits that I can't get rid of. I'm going to put another thin coat of resin on and call it a day (once I get the wax off). What is g3?


Are you using a male or female mould? If you are using a female mould I have gotten spectacular finishes with no post work by simply painting some resin on the mould first and letting it tack up a bit before setting the first ply down. It got rid of all the air bubbles you sometimes get on the first ply.

RK - 12/1/13 at 08:30 PM

No! Lacquer turns out awful! I've tried to paint a guitar MANY times, with the same smelly, terrible results. i clearly (ahem...) just don't get it. I've tried cans, and a spray gun.

I am skinning. The other bits (all flat) done on glass turn out smooth, but very dull and scratchy.

I've watched a hundred videos on how to do this stuff, am on here every day, but when I go to do it, it turns out really, really badly. My car has been built and rebuilt at least 4 times, with 3 engines, two of which worked for about an hour each (yes folks, I am persistent), and I've painted a guitar 3 times. If there was a course to take or something, on how to paint, I would do it.

I appreciate all the encouragement though; but that's life.

[Edited on 12/1/13 by RK]

umgrybab - 12/1/13 at 08:53 PM

quote:
Originally posted by RK
No! Lacquer turns out awful! I've tried to paint a guitar MANY times, with the same smelly, terrible results. i clearly (ahem...) just don't get it. I've tried cans, and a spray gun.

I am skinning. The other bits (all flat) done on glass turn out smooth, but very dull and scratchy.

I've watched a hundred videos on how to do this stuff, am on here every day, but when I go to do it, it turns out really, really badly. My car has been built and rebuilt at least 4 times, with 3 engines, two of which worked for about an hour each (yes folks, I am persistent), and I've painted a guitar 3 times. If there was a course to take or something, on how to paint, I would do it.

I appreciate all the encouragement though; but that's life.

[Edited on 12/1/13 by RK]


Go down your local Canadian Tyre and buy yourself a can of clear laquer then apply it to your CFRP part sanded to no more than 300 grit and you can have a fantastic finish like this. Description
Description
One thing you may need to do is make sure you're applying it thick enough. If you skimp on aerosol application you can easily get misses or if you're too far away and not careful you can get overspray where dried particles are depositing in the surface of the damp laquer causing a pebbled or cloudy appearance. You can usually get rid of this with some wet clay polishing though.

RK - 12/1/13 at 09:01 PM

I know people think I am crazy, but it seriously comes out lumpy and horrible, every time. All sorts of different ambient temps too. I won't use lacquer anymore due to the smell.

ashg - 13/1/13 at 12:34 AM

g3 is a professional polishing compound

http://www.farecla.co.uk/products/g3-premium-range

its not possible to go from 2000grit paper straight to autoglym its nowhere near abrasive enough. if you polish it about 500times with autoglym you may eventually get it to shine if your hand doesn't fall off.

so to reiterate you need a proper electric polisher and proper polishing compound to get it shiny, which is what 99% of people do on gelcoat to get a good deep shine, principal is exactly the same for CF.

RK - 13/1/13 at 01:04 AM

thanks ash, starting to make sense now!

Carbonman - 13/1/13 at 07:27 AM

A lot depends on what Resin you used Epoxy,Polyester etc.
If when you wet sand the water turns grey/black then you have gone too far. You have gone through the resin and into the reinforcement (Carbon). Once this happens you will never polish to a gloss. You will either have to apply more resin or clear coat.
If you have already tried polishing the part then polish/silicone etc will be impregnated into the fibres of the cf and you will never get it out even with degreaser/panel wipe. This will leave pin holes in the surface of whatever coating you now try to apply.

fullpint - 13/1/13 at 08:07 AM

When I was at Dymag they used G-3 as a final buff. It can help if the mould is polished first prior to seal release going on.
The carbon car wheels also has a clear final coat applied. Using a very expensive laquer thats used on carbon fibre boat hulls.. Results were awesome though.

40inches - 13/1/13 at 11:56 AM

I have had very good results using G10