Originally Posted by open1your1eyes0
I think the problem is carbon fiber on it's own with just a clear coat would be as fragile as thin glass so they have to add some metallic powder into the mix to give it toughness from drops and cracks and such. Obviously that metallic powder would interfere on signal isolation but this is just my theory why it doesn't work, not 100% sure.
The reason genuine Carbon Fiber attenuate RF signals, is not because of some coating or the chemicals used. Carbon Fiber is INCREDIBLY strong all by itself, no need to add anything it.
It is because of the structure of Carbon Fiber itself; it is a fabric, it is constituted of a large amount of individual fibers weaved together, in essence you have a large polarized (all fibers in the same direction) shield, and then another large polarized shield rotated 90 degrees (they are at least 2 layer of Carbon fiber fabric in the final product, some time 3 or more). This is a pretty efficient RF shield.
Source: I build my own carbon fiber back covers...