Special Effect Paint Sticks are super-concentrated encaustic paints, especially useful when creating encaustic monotypes.
Violet Bronzing is warm violet metallic shimmer.
On raw paper on a hot palette, the mass tone lands and around that a halo sometimes forms of the contrasting color, in this case a cool gray.
The reason these are separate from Metallics is that I don't think people should use them for brush painting on panels. If that gray can't flow onto the paper, it has the potential to rise to the surface over time and look rusty. It is actual metal, after all. The bleed on paper removes any chance of that rusty look on the surface.
-- H. Evans, paint maker