Devcon two part waterproof and uv resistant 2ton epoxy, mix and let thicken for 5-7 min, then use a tooth pick to pick up epoxy and coat grooves (clean with 70%isopropanol first), after 12 hrs sand with 110 then 220 then 440 sandpaper until nearly flush with surface, after 24 hr polish with 600 and 1200paper to a flush finish. The original surface is harder than the new epoxy, so by applying careful pressure with sandpaper and a block of wood you will not remove it. Now it helps if the wing was cured under pressure and heat like AFS solid wings, that makes it really hard to sand off the original surface.

Adding black pigment/graphite sounds like a great idea. I used marine tex and it dries gray, which didn't look as good at black. A soft sanding block, from a auto paint store helps reforming damaged edges. I tried a brushed on laminating epoxy clear coat after the repair. First a laminating epoxy that ran, then a thixo epoxy that didn't run but humped up due to surface tension. Maybe others have had success with clear coating, but I just had a mess. In the end the epoxy clear coating sucked up a lot of time and produced mediocore results. I would have been better off with pigmenting my marine tex and forgetting the clear coat.

thanks for all the advice will be experimenting on this wing as I have just bought a new one from Patrik