My take, after thinking about things for a while is this:
Everyone loves BlackFire at first, because it shines like crazy and has that warm glow, right? But then, for reasons unbeknownst to anyone, the beading goes away and the water sheets or sticks to the panel, right?
I believe that the abrasives in BF abrade the clear coat on a very minor level (not quite microscopic, but close). The fillers (oils) then hide the abrasions, and the result is a shiny surface that beads water.
Note: when I first looked at the CD's, prior to the Dawn wash, the BF'd cd's looked pretty good (other than the marker being worn away) - a result of the oils and fillers hiding the abrasions.
Then, after a wash or two, the oils go away, and the abraded surface is left behind, exposed. The abrasions (peaks/valleys) "grab" the water, which causes the water to cling rather than sheet or bead.
This would explain why on that 2002 E430 that I detailed with BF that the paint stopped beading after the BF wore off; fresh unprotected paint will bead water until it is abraded enough.
I agree that CD's are not the same as clear coat on a car, but they do offer some insight as to a relative abrasiveness (sp?) of a product. I did this for comparison purposes only and not as a means to say that product X *will* scratch your car, etc.
Just some food for thought...
