Hi, I am skinning an item in carbon fibre.

I have laid the carbon and sealed it with 3 layers of resin which is fully cured. I always use 400grot paper here to completely flat out the surface before one final thin  coat of resin.

I have been unable to sand out some of the low spots with 400grit. My question is, how low can I go in terms of sandpaper grit here? Will a coat of resin hide the scratch marks of a 200grit or maybe even a 120grit paper?

Thanks in advance for any help you can give.

Whilst trying to find the answer to my own question. I have come across a statement that generally I need to do a coat of lacquer over the top to ensure that I the parts do not discolour yellow over time. 

Is this the case with XCR resin? Will I need to lacquer it to keep it looking new?

You can go quite coarse, eg 240 grit, as long as you work your way back up the grits if you want to lacquer or polish it.  The XCR has a high level of UV resistance but is not 100% UV stable so in very sunny climates with high UV exposure, you may want to consider a UV stable lacquer.

Also remember you might want to do a post cure if said environment is warm too.  On a hot sunny day, the resin can soften if you don't do a post cure.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant