Canadian Chrysotile Asbestos Classification and the Quebec Standard Testing Machine, Reprint from Asbestos Magazine (1951)

A three-page reprint, dated January 1, 1951 and sold for 25 cents by the trade journal Asbestos of Philadelphia, giving the "List of Standard Grades" for Canadian chrysotile set up by the Committee on Uniform Classification and Grading of Asbestos Mines Products. The committee, it says, "was formed in 1931 at the instigation of the Minister of Mines of the Province of Quebec," and the list was last revised in December 1942. It defines crude and milled asbestos, lists the milled grades in groups 3 to 9 with their guaranteed minimum shipping tests, and adds the Quebec Asbestos Mining Association's approved method of sampling and testing fiber on the Quebec Standard Testing Machine, with a photograph of the machine.

What it shows

The grades are defined by how a 16-ounce sample of fiber splits across the machine's three screens and its bottom pan after exactly 600 turns. The reprint's example: a customer buying 3K fiber of the specification 4-7-4-1 should find 4 ounces left on the top screen, 7 on the second, 4 on the third and 1 in the pan. The longer the fiber, the higher the grade and "the greater its value." These are the grade codes (3K, 4T, 7R and so on) that appear on mining companies' price lists and fiber data sheets for decades afterward; see the Quebec Standard Test. The association's testing rules carry a note that it was "Formerly Quebec Asbestos Producers' Association." Nothing in the reprint concerns health.