Originally Posted by
Jerrybass
Ed, thanks for the link to the crox. I notice that this crox is apparently mostly used as a pigment (as are many of the others I see online). I am not positive, but I think that if you look at the spec sheet at the link you provided, you will see a Chemical Accession Number (CAS-No.) which in this case is 1308-38-9. Someone more knowledgeable than me on this may be able to verify that this number is pretty much a unique identifier for the material. I bet if we look around a bit, we can find a U.S. distributor of material having the same CAS number for use in paints or cosmetics or the like if not specifically as an abrasive. If that is the case, it may open up a few new sources for this stuff.
BTW, the spec sheet for the Kremer crox says that the purity is 98.5% to 99.5% Cr3O2 with predominant particle size of .3um. There is no maximum particle size specified, but if I read it correctly, up to .02% could be trapped in a .045mm (=45um) sieve. This suggests to me that this powder could include particles with a dimension greater than 45 microns in some direction. I am by no means a chemist or expert on this type of thing, but I have a client in the nanotechnology business dealing primarily with nano-carbon particles. If there is any similarity, it is possible that the larger particles are actually agglomerates of smaller particles which when spread on a strop might well break down quickly and disburse into the basic particles averaging .3um in size. (incidentally, the definition of particle size for irregular particles appears to be a little fuzzy, but often means the size in the longest direction, but there are other definitions too!) If people are successfully using the stuff for stropping, the possible presence of larger particles is probably a non-issue. But just couldn't keep the engineer in me beat back :) .