RE: MICROBALLOONS?
It would depend upon what you were using to measure the talc with--volume, or mass. Using volume, and talcum powder, then you'd get the same amount of entrained air that is present within the bottle.
Talc itself (as found in the stone state) may well be that dense, but we aren't talking about using talc stone, we're talking about using the ground up stuff--with all of the entrained air present. At least, that's what I get from the thread.