over the past months, I've become very used to painting with extremely thin paint. GW colors mixed with lots of water (milk consistency), applied in layers, or straight ink.
I could not get this to work with the metallic colors though. If I thin them with water, they don't really get thinner, but the individual specks of metal just get spaced farther apart, giving a very unsatisfactory result. Even when applied in multiple layers.
Additionally, the metals seem to dry very very quick - if I use them un-diluted, they seem to dry on the way from the pot to the mini, giving either a spotty look on the mini, or a damaged brush, or both. If I add only very little water, just to keep them from drying so quickly, they still seem to try very fast on the surface, creating some sort of "skin".
I have tried water and some "metallic thinner" stuff, with comparably bad results.
Any hints on the metallic colors? How do you work with them? Do you know what I mean? Do you use other colors maybe (not GW ones)? Is that normal, and NMM is the answer?