Black spots on carbon frame?

[nmoerland]

I received a frameset from a reputable Chinese manufacturer. When inspecting the frame there are visible black spots (in particular on the rear end triangle and bottom bracket) trough which no carbon fiber is visible. Do any of you know what this is? Possible black resin, filler or even carbon fiber?

Seems they didnt sand it away on purpose, because halfway the rearstays it's sanded down to the carbon. However I would love to do a naked carbon painting, which wont turn out so nice with these black spots I'm afraid.

[patliean1]

It's likely paint primer overspray. I ordered my Dengfu R12 in raw carbon and the factory still applied some sort of primer.

Not sure how many companies offer "true" raw carbon, in order to preserve the integrity of resin.

[St0mpB0x]

Most commonly these manufacturers paint some or of all the joints black. I'm not totally sure why. I suspect part of it is because it's typically where frame sections are bonded which don't always look super pretty so they do it to avoid people going "omg you sent me a broken frame". Nope, thats just where the sections are glued together. Its very likely you can just sand the black paint off but you won't know how pretty it looks underneath until you get in there.