I decided to email Tandy about their white rouge, they sent me a copy of the MSDS and this is what it said
SECTION 1. IDENTIFICATION OF THE SUBSTANCE/PREPARATION AND COMPANY
PRODUCT IDENTITY:
WHITE ROUGE
COMPANY IDENTITY: THUNDERBIRD SUPPLY CORP
SECTION 2. COMPOSITION/INFORMATION ON INGREDIENTS
85-95% ALUMINUM OXIDE
I made a call to Thunderbird and asked about the grit size, (they first had to call someone else) , they told me the best that they could find out was that it is some where between 1 and 5 microns. Must be what they call quality control
Looking on the web I found this Grit to Micron chart that says it could be between 4500 and 14000 grit.
http://www.facetingmachines.com/grit-mesh-micron.shtml
I suppose that each bar could be checked to see what it does under some magnification to see if its useful. Right now it seems my Silver Steel blade is the only one that responds to it.
Bob