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Asbestos: how was asbestos material classified for purposes of manufacturing asbestos-containing products: classifications of raw or mined asbestos ore, fibers, or dust. Here we describe the standard asbestos product material classes that were based on fiber length and other properties.
This articles series about the manufacture & use of asbestos-containing products includes detailed information on the production methods, asbestos content, and the identity and use of asbestos-containing materials.
Grading of asbestos is generally (lone on the basis of
length rather than on quality. The qualities winch are important
to the fibers are flexibility and fineness. The more
flexible and fine fibers are used for spinning and weaving
textile products. The shorter milled fibers are used in such
varied products as asbestos-cement and tile.
[Click to enlarge any image]
The Canadian Asbestos Producers' have set up what is
referred to as the Quebec Standard Asbestos Testing Machine
for classifying milled asbestos. This method is based
on the mechanical sieving of fibers. There has been a general
trend to adopt the Canadian Standards Classification;
however, many of the mines in Canada still retain their own
methods which are specifically tailored to their customers.
The classification divides chrysotile into two main classes—
crude and milled asbestos.
The crude asbestos consists of the hand selected crossveining
material essentially in its native or unfiberized form.
Its length can be determined by combing. Milled asbestos
consists of all grades produced by the mechanical treatment
of asbestos ore. These two main divisions are subdivided into
different groups ranging from group No. 1 to No. 9. Some
of these groups are listed in Table 1.1. [Click to see an enlarged, detailed version of this table]
Table 1.1. Classification of Some Types of Chrysotile Asbestos According to Groups
The Quebec Standard Asbestos Testing Machine consists
of three stacked screens and a pan which rests on a
table. See Figure 1.3. These screens are driven by an eccentric
gear so that an elliptical motion is produced on the screens. Each screen measures 24½ in. by 144 in. with each
of the boxes being 3
1/2 in. in depth. The top box which is
identified as box 1 consists of a wire screen with
1/9 in. openings,
box 2 has a 4-mesh wire, box 3 has a 10-mesh wire
and box 4 is a closed receptacle which collects all matter
filtered through the other three boxes. The motion of the
boxes and the time that the fibers are subjected to that motion
The test procedure is such, that it introduces 16 oz. of
asbestos on the top tray. After two minutes of motion, the
fiber in each tray is weighed. The more fiber retained on the
first screen and the less fiber falling into the pan the higher
the grade of product. As an example Group No. 3D specifies
The greatest increase in the use of fibers has been in the
shorter lengths that comprise approximately 50 per cent of
Canadian asbestos production. The classification of shorts
and floats follows the same principle of the shaker test;
however, other factors such as bulk, grit percentage, and
viscosity are involved.
The term refuse is a railway freight
classification; it does not mean that shorts and floats are
byproducts of asbestos milling. As the names imply, floats
and shorts are fibers so fine and light that they are collected
by air flotation. They are precipitated into float chambers
by gravity settling or collected by filtering media.
Shorts and floats have shown a remarkable increase in use
for several reasons. Quality improvements have developed
new uses; improved finished products have resulted in the
shorter fibers supplementing some of the longer fiber applications.
Markets have expanded for such relatively new or
growing industries as the vinyl tile, plastics, asphalts, and
Other methods of classifying fibers have different identifications depending upon the type of asbestos, length of fiber,
fiberization, and other characteristics. In some cases, the
mines add additional letters or numbers to the Quebec Standard
Testing Machine nomenclature for these products.
Asbestos designations by other methods do not tally with
the Quebec. Classification. Other asbestos classification methods are reviewed in
Table 1.2 shown below.
Table 1.2 - Classifications of Types of Asbestos Fibers & Materials
[Click to see an enlarged, detailed version of this table or its continuation just below]
Various machines and apparatus are available for obtaining
accurate measurements of the length of asbestos. One of
these units is identified as the Bauer-McNett Classifier; it
is manufactured by the Bauer Brothers Company, Springfield,
Ohio. This apparatus utilizes four elliptical tanks, each
with a screen of different mesh. The four tanks are arranged
in cascade so that the material introduced into the highest
tank passes by gravity through the other three, and the
discharge from the lowest tank carries the finest material to
waste. Each tank has a drain at the bottom which is closed
by a stopper.
The screen in each tank holds back fibers
greater in length than the size of its opening. The coarsest
mesh is in the top tank. Screens of different size mesh are
used with the equipment.
Asbestos, Its Industrial Applications - Rosato: Text& Chapter Index 
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 Asbestos, its Industrial Applications, D.V. Rosato, engineering consultant, Newton MA, Reinhold Publishing Co., NY, 1959, Library of Congress Catalog No. 59-12535. We are in process of re-publishing this interesting text. Excerpts & adaptations are found in InspectApedia.com articles on asbestos history, production & visual identification in and on buildings.
 "Asbestos in Plastic Compositions", A.B. Cummins, Modern Plastics [un-dated, pre 1952]
 "Asbestos in Your Home," Spokane County Air Pollution Control Authority, Spokane WA 509-477-4727 www.scapa.org provides a one-page image, a .pdf file drawing of a house warning of some possible sources of asbestos in the home. The sources are not ranked according to actual risk of releasing hazardous levels of airborne asbestos fibers and the list is useful but incomplete.
 The US EPA provides a sample list of asbestos containing products epa.gov/earth1r6/6pd/asbestos/asbmatl.htm
 "Characterization of asbestos exposure among
automotive mechanics servicing and handling
asbestos-containing materials", Gary Scott Dotson, University of South Florida, 1 June 2006, web search 3/9/2012 original source: scholarcommons.usf.edu/cgi/viewcontent.cgi?article=3505&context=etd [copy on file as /hazmat/Automotive_Asbestos_Exposuret.pdf ].
 Asbestos Identification and Testing References
Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed
the basis for current work by asbestos identification laboratories.
Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone
 Asbestos in Your Home U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
 Asbestos products and their history and use in various building materials such as asphalt and vinyl flooring includes discussion which draws on Asbestos, Its Industrial Applications, D.V. Rosato, engineering consultant, Newton, MA, Reinhold Publishing, 1959 Library of Congress Catalog Card No.: 59-12535 (out of print, text and images available at InspectAPedia.com).
 "Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
 EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460 Copy on file as - /hazmat/Asbestos_in_Your_Home_US_EPA.pdf - Asbestos in Your Home - U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
Basic Information about Asbestos, US EPA, web search 08/17/2010, original source: http://www.epa.gov/asbestos/pubs/help.html
"Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
Copy on file as - /hazmat/Asbestos_in_Your_Home_US_EPA.pdf - Asbestos in Your Home - U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
[copy on file as /hazmat/Vermiculite_US_EPA.pdf/ Current Best Practices for Vermiculite Attic Insulation - May 2003, U.S. EPA
[copy on file as] /hazmat/Vermiculite_Health_Canada.pdf] Vermiculite Insulation Containing Amphibole Asbestos - September 2009, Health Canada
Managing Asbestos in Place, How to Develop and Maintain a Building Asbestos Operations and Maintenance (O&M) Program, U.S. EPA, web search 01/20/2011, original source: http://www.epa.gov/asbestos/pubs/management_in_place.html
Asbestos Strategies, Lessons Learned about Management and Use of Asbestos: Report of Findings and Recommendations on the Use and Management of Asbestos, 16 May 2003, US EPA, web search 01/20/2011, original source: http://www.epa.gov/asbestos/pubs/asbstrategiesrptgetf.pdf
prepared by the: Global Environment & Technology Foundation, 7010 Little River Turnpike, Suite. 460, Annandale VA 20003
Other US EPA Publications on asbestos: web search 01/20/2011, see http://www.epa.gov/asbestos/pubs/pubs.html
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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