Be seeing you
Their recent Science of Paint article claims "Some contrast paints are suspensions, while others are actually dyes", so it's probably less one universal approach across the whole line and more "A bunch of different solutions for different colors depending on different pigment behaviors, designed individually so they all behave close to the same even though the science might differ depending on which color you're looking at."Huh. Any pigment light / small enough to float up would also float over the heavier pigment in thicker bits in the recesses. So this would need to be a totally transparent pigment, or else the lighter would “overwrite” the heavier.
It sounds most likely to me to be a transparent paint with a carefully calibrated viscosity and probably a certain amount of sales hype.
Which probably means some Contrast paints will be really useful and some will kinda comparatively sucks, though I don't doubt GW will have put a lot of dev into ensuring none of them such too much.
Leaked stock lists suggest this is going to be bigger than just the release of the Contrast line -- GW is also re-launching all the formerly-thought-discontinued ForgeWorld specialist paint for general distribution, including their clear colors, which are designed to be even more transparent and look even better over metallics than that.Thanks for sharing that video, the black over metallic looks gorgeous :O
(They're also replacing their white paint with a better one. Again.)