carbon fiber repair

Gene Cassone said:

I am looking for help in repairing superficial scratches on carbon fiber pieces. Scatches show as white streaks against the black carbon fiber. One is through the outermost coat but not to the carbon weave itself. Can the scratches be filled and polished in place?

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Depending on the severity they can usually be wet sanded and polished out by hand.. Use 400 - 600 grit wet .. followed by a light wax / polishing compound and a wool buffing wheel at low speed.

Gene Cassone said:

I am looking for help in repairing superficial scratches on carbon fiber pieces. Scatches show as white streaks against the black carbon fiber. One is through the outermost coat but not to the carbon weave itself. Can the scratches be filled and polished in place?

Click to expand...

give Kip Ewing a call, he would likely have suggestions for CF repair.

Gene Cassone said:

I am looking for help in repairing superficial scratches on carbon fiber pieces. Scatches show as white streaks against the black carbon fiber. One is through the outermost coat but not to the carbon weave itself. Can the scratches be filled and polished in place?

Click to expand...

Hi Gene,

Funny, I just tried to repair some carbon the other day that got scratched.
I used a dremel tool with a polishing wheel and some polishing compond. But I made the mistake of spinning to fast and it seemed to melt the epoxy. Be carefull with that, I think you may want to hand polish it at he end so you don't melt it like I did. I know it can be done. I have seen carbon bicycles get badly damaged and then repaired. Good luck, don't melt the carbon!

Jake

Gene Cassone said:

Thanks for the help. Can the scratches be filled in (with epoxy?) before polishing?

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Gene,
Some CF parts use the CF resin as the finish coat. Some CF parts are sprayed with an automotive clear coat over the Resin. Typically it is best to try to fill the scratch with the compatible material. You could try some clear epoxy resin in a small area. Just make sure to clean the area to remove any wax or oil residue.

FYI there are 2 major types of resin used in CF construction. Epoxy, and polyester. The polyester has a lower temperature threshold for the most part. Most cosmetic non prepreg CF is done in polyester resin.

freeflyer said:

FYI there are 2 major types of resin used in CF construction. Epoxy, and polyester. The polyester has a lower temperature threshold for the most part. Most cosmetic non prepreg CF is done in polyester resin.

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Actually many parts in carbon fiber are done in Vinyl ester which is a modified epoxy that is used like polyester.
If you have to fill the scrathes, I would try using the automotive clear urethane. Go to a collison shop and be ready to use it there, and I am sure they would give you a small amount already mixed. Many guys actually mix up more than is needed to spray up on a vehicle and will dump out the leftovers. If you take a plastic cup and a small artists brush, you could fill the scratch and then sand and polish as stormcat said. I would be careful while wet sanding since you never know how thin the clear coat was around the area. Then polish it with a low speed wool pad and polishing compound.
Start off with 400-600 and work your way up to a 1200 grit wet sandpaper.
This will polish better. Stormcat is correct about epoxy being used on some, but the automotive clear coat is clear enough that it won't normally show.
I hope this helps!

Be careful using epoxy unless you know how yellow it gets when it has been cured for a while.