Not sure on the grain yet, just ordered last night :-)
So you would spray the black candy over a solid grey? or over a grey primer?
The IC-1 doesn't have a binding so phew! It was time consuming (but worth it) when i did that on my PBG Tele.
I don't have a spray gun or air brush so looking at how to do a thin burst with spray cans (not the wisest choice but....)