Just wondering, can carbon be sand-blasted or etched?
Basically I have just bought a CFRP monocoque chassis.  I got it at a substantial discount as while it is structurally sound, it is cosmetically flawed due to being post-cured at too high temperature, causing some rippling in the surface in a few areas.  I need to decide on the best way to smooth the surface ready for painting.  If I was to sand the ripples off with normal abrasive paper until the surface was smooth I fear I would be weakening the structure, as I'd be sanding down into the fiber before I got down to the bottom of the ripples.  Another option I have considered is to put filler in the ripples, however sanding into the bottom of the "valleys" would be awkward with normal sandpaper in order to give the filler a key to bond to.  So I was wondering, is there anyway I could lightly sandblast these areas in order to get a nice key for applying filler in the low spots, or alternatively, is there some chemical I could apply to the surface to lightly etch the surface of the resin in order to give a key to body filler?

May thanks, lee.

kind of interested in this topic as well, just know if you could sandblast before clearcoat (to save some time sanding) 

Hi whats the chassis for ? and any chance of pictures of the "rippling"

Not planning on using it in anger are you ? hard to tell till we know more but I have probably made 250 tubs for f1,le mans,f3 etc  and I have never known  a finished chassis to be post cured

If it has been I would be going round tappin g looking for delams

Depending on what media you use to sandblast, I would be afraid that it would be aggressive like stated above. I often sand blast motorcycle frames and other parts to prep for paint. I always have to spray primer (obviously for the paint to stick) but also cause the surface is to rough to just spray paint and clear over. The primer is put on in several layers then sanded smooth. Unless you are going to prime paint, then clear I would think it would turn out terrible. Good surface for filler to adhere to though depending on how deal they are and other can chime in on this. could you take a red scotch bright pad, stuff the valleys and ripples up and recoat with resin and sand smooth. Then scuff up the whole thing once level and reclear that way?

I would like to have a play around with a sodablaster one day, snap on do one ...

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David Stevens
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RC Car Touring Body 1/10 Scale

When I've prepared composite parts or inserts for bonding, we usually use a vapormat machine, which is effectively a wet sand blaster.

I normally just use a brass/bronze bristled brush .. for larger areas I use one of the ones you buy to clean your barbeque grill ...  It gets into the low spots no problem, and if you're carefull, it will just lightly abrade the surface, just enough to get a good bond ..

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