CFRP Mudguard Restoration
Figured I'd post up my amateur attempt at restoring the carbon fibre rear mudguard on my bike.
Full disclaimer though. I am no composite experts or paint guru, just some schmuck with some sandpaper and a few rattle cans so take this with a pinch of salt.
When I got my bike, the mudguard was already pretty degraded with cracks and UV damage across the entire piece.
My hope was that the damage was confined to the clearcoat and that the resin matrix underneath was still okay.
Bits and bobs used:
- Various grades of wet/dry sandpaper 120 grit - 800 grit (I believe higher finishing grits will yield better results but that was what I had available)
- Acrylic clear lacquer spray can
- Latex gloves
- Bucket of water
- Lint free cloth
I started off with 120 grit, trying to avoid any parts where the resin was exposed as much as possible. Just looking to get most of the clearcoat off.
Every few minutes I'd stop sanding, wiping all the residue off and drying the part so I could see how I was progressing without the water blending all the imperfections out of view.
Feeling that 120 grit was too aggressive, I pretty quickly switched I switched to 240 grit then to 400 grit (then back to 240 grit for bits that I missed.
At this point it was not pretty, bits of the clearcoat were flaking off and I was starting to see the carbon fibre weave starting to come through on exposed bits(little black spots). UV damage was pretty evident in several places (Yellowish patches) but at least the cracks were going away.
I continued until I had got rid of the flaking sections and the remaining cracks in the clearcoat were just hairlines. At that point I decided that caution was the better part of valor (at least that's my excuse for laziness and I'm sticking to it).
After giving the mudguard a good wash and wipe down with some spirits, it was then treated to a light coat of lacquer. The lacquer was left to set for a few hours then lightly sanded down with 800 grit to try and get rid of any overspray and the obligatory curious insects.
This process was repeated with 5 more coats. As I didn't have any really high grit sandpaper or a rotary buffer the final coat was left to cure then just given some elbow grease with some polishing compound, so if you look close you can see some orange peel.
Overall I'm fairly happy with the result. It's stood up to over 2,000km of riding so far without any cracking and it no longer looks like spiderman jizzed all over the back of my bike.