Stone Grades 101

>>Stone Grades 101
Stone Grades 101 2018-05-17T13:11:16-06:00

Welcome to Arkansas Stone Grades 101

Natural Arkansas Whetstones are available in various grades and classifications.  Users should be aware that color is not the determining factor in grading Novaculite.  Some users have been defining whetstone grades by color, but the same colors may be seen in more than one grade and classification.  Different grades of Novaculite also have a noticeable difference in texture.  The softer the stone, the coarser the surface of the stone feels; harder stones, such as the True Hard and Translucent, have  a smoother glassy feel.

How to Choose an Arkansas Stone Grade to Suit Your Needs

Soft Arkansas
(Medium) is the most popular of the grades of Novaculite.  It is an all-purpose stone used by woodcarvers, sportsmen, butchers, commercial knife sharpeners and even housewives.  This stone is used by people who desire keen, sharp edge on their knives and tools in a minimum amount of time.  Soft Arkansas stones may be  white, gray and black, or pink and gray in color.

Hard Arkansas (Fine) is most suitable for fine polishing and the maintenance of a fine edge on knives or tools.  Hard Arkansas is often referred to as “White Hard.”  However, users should be aware that Hard Arkansas often has color variations also.  To our knowledge, this color does not interfere with the honing process by any means.  Hard Arkansas stones are popular among woodcrafters and a variety of industries including the dental industry.

True Hard Arkansas (Extra Fine) is the finest grade abrasive available today.  It is most commonly used for industrial applications where an extremely fine polish is required.  True Hard Arkansas stones are often referred to as Multi-Colored Translucent; colors, both opaque and translucent, are random and may include black, red, white, and gray–often within the same stone.

 Translucent Arkansas (Extra Fine) stones are classifications included in the True Hard Arkansas grade category according to specific gravity under density standards.  The reason there is a classification in this grade is because of color preferences by customers.  Translucent stones may be a uniform, translucent shade of gray white yellow, brown and sometimes even pink.

 Black Arkansas (Ultra Fine)  Black Arkansas stones are black or blue-black in color.  This crypto-crystaline novaculite structure is the most dense and therefore has the properties to achieve the finest polished edge possible.

           Dan’s Whetstone Company has TRUE HARD, TRANSLUCENT and BLACK stones available in all published sizes and shapes.

 Arkansas Stone Grade Table
* This table does not reflect manmade stone grades*                                                                     

Who they are: How They Grade Natural Arkansas Stones:
Arkansas Geological Commission Washita Arkansas
A Leading Stone Manufacturer Soft
(referred to as Extra Fine in regards
to manmade stones)
(referred to as Ultra Fine in regards
to manmade stones)
A Leading Bonded Abrasive Manufacturer Very Soft Semi-Hard
(incorrectly refers to this as flawed Ultra-Hard Stone)
U.S. Federal Government
Soft Hard
U.S. Federal Government
Soft Hard
Dan’s Whetstone
Company, Inc.
How Dan’s Whetstone Company, Inc. Grades Natural Arkansas Stones:
(limited availability)
Soft Arkansas Hard Arkansas True Hard Arkansas Translucent Arkansas Black Hard Arkansas
How Fine Coarse Medium Fine                                     Extra Fine                                                      Ultra Fine
Related Grit Size 400-600 600-800 800-1000 1200+
Specific Gravity 2.25 or less 2.25-2.30 2.30-2.45 2.50 or more
Colors(not all inclusive or limited to any particular grade) WhitePurple, White & Orange Gray, White,Black & GrayGray & PinkBlack & WhiteWhite, White & Pink
Black, Gray, White, Red
(combination of two or more colors occurs frequently)
Translucent Gray
Translucent Yellow
Translucent Brown
Translucent Pink
Black, Blue-black

Ever Heard  “Don’t Judge a Book By Its Cover?”
The same is true when it comes to your stones.  The texture of the finished stone surface may vary from the natural texture of the stone because the stones are produced using fine grit to lap, or finish, the stone.  After using the stone one may notice a slight change in texture as the surface finish is worn and the true abrasive quality of the stone surfaces.

Does Dan’s Arkansas Whetstones Meet Federal Standards?
Although there may be only a slight difference in grain size from one grade to another, the effective abrasiveness of each grade is related to the density, or compactness, of the individual, bladed quartz crystals that compose Novaculite.   The U.S. government measures the specific gravity of Novaculite and assigns density ranges for the Soft and Hard classifications.  Dan’s Whetstone Company, Inc., follows these standards for Soft and Hard stones.  We also further define Hard grade Novaculite into the True Hard, Black, and Translucent categories.

Density Standards

Soft Arkansas
Hard Arkansas
True Hard Arkansas
….Colored Translucent
….Black Arkansas
2.50 +
2.50 +
2.50 +
2.50 +
Specific Gravity
Specific Gravity
Specific Gravity
Specific Gravity
Specific Gravity
Specific Gravity

 Please note that as the table indicates, the specific gravity of Novaculite will vary from stone to stone.   Every stone is not measured—the costs involved that would have to be passed on to consumers are too great for that.

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