This is a very interesting source for CrOx.
Here is or link to the product data sheet:
http://kremer-pigmente.de/shopint/Pu...les/44200e.pdf

I also find this Fe2O3 pigment interesting:
Iron Oxide Red 130 B - Iron Oxide Pigments - Kremer Pigmente GmbH & Co. KG

Iron oxides cut faster than CrOx. The particle size of 0.22 um would be ok.