Thread: Another whats under the stone post.

I have a Washita that is similarly colored. Great stone for me.

Stewie may be right in this case. The volume (not mass, as he inadvertently labeled it) of the stone if it's a Hard Ark or Washita would be less than his calculated volume, because Hard Arks and Washitas are somewhat porous (not to mention any missing volume due to chamfers, corner rounding etc). Less volume means the density would actually be slightly higher than his calculated density. Thusly it would pretty much have to be a Hard Ark if it's really from the Ark family of stones.

Had the opportunity to test this stone out to form a secondary bevel on 1 of my workshop chisels. The stone itself retained a good level of oil on the top surface of the stone, and there was no need to add further oil while working the stone. Fairly impressive given its a rather hot day outside, and a few degrees hotter within the workshop. The stone is a very slow release stone, with little sign of slurry release. The top surface of the stone is what I classify as hard to very hard. As noted within my opening post, using the ANSI Standard, based it suggests the range of grit at 800 - 1000. I have some slight concerns with how the ANSI and JSI Standards vary greatly from that being stated by a lot of natural stone suppliers. Japanese nat stones being a relevant example. Based on what is being declared by these Japanese nat stone suppliers, I would rate this stone equivalent to 8000 grit. This is to large extent based on the level of sheen left on the steel after being worked by the stone. The finer the scratches, the higher the grit, the change in sheen to reflective shine. Some alloy steels such as A2 and PM may vary slightly from this principle. Moving on to the photo's, the 1st photo shows the secondary bevel after being worked by the stone. The 2nd photo shows both the primary and secondary bevels after a dozen strokes on the pure chromium oxide impregnated leather stropping block. The end result is a very sharp cutting edge.

regards StewieS;

Of interest, if I were to reduce the total weight of this stone by 25g (4.8% of its current weight), it would still be borderline high of a Washita's range of SG. (2.25 or under)

StewieS;

Originally Posted by StewieS

~~~~ using the ANSI Standard, based it suggests the range of grit at 800 - 1000. I have some slight concerns with how the ANSI and JSI Standards vary greatly ~~~~~ I would rate this stone equivalent to 8000 grit.~~~~~

Yep that is how Ark's work, Dan's appears to be the cause of these inaccurate grit ratings, my opinion (not fact) Dan seem to rate his Ark's based on what the grit would be if you could remove a quartz crystal from the stone and measure it, which is just not reality on the hard ark's as they don't release slurry unless your doing something crazy like sharpening an axe with lots of pressure and gauging out bits of rock, I might also mention not all quarry's are the same.

Also burnishing of hard/translucent/hard black(SB) can bring them up into the 15k to 20k+ range on some stones when honing with light pressure such as a razor, it is more about how they work than any grit rating, so in effect I am saying my prior sentence about 15-20k is bad form as well, I would prefer to never even mention a grit rating on Ark's but people like numbers.
I would really like to just call them as Washita = medium, Translucent/SB = finisher and polisher etc.

my .3 cents.

That stone is loaded with oil, so how it looks can change. I have remove all the oil from all my Arks and use them with water and Smith’s water soluble Honing Solution. Removing all the oil can take some time, it took years of soaking in dirty swarf and oil to look like it does.

All that counts, is how it performs. If you have other Arks, compare it to them to see where it will fit in your progression.

You cannot grit rate natural stones, but you can compare them to known grit stones, and even that can change from one side to the other. A shiny bevel and especially one stropped, on Chrome Oxide, tells you nothing about the stone.

What the stone is called, or looks like, does not matter as much, as how it performs. If you are going to hone razors, on that stone, I would use one side for tool and a smooth prepped side for razors.

I doubt it is a finisher for razors. Blacks and Tranlucent’s, are much better finishers for razors.

Euclid; you may want to refer to work of the late Henk Bos, who applied a grit rating to the natural stones featured within his website. https://bosq.home.xs4all.nl/info%202...ing_part_3.pdf

StewieS.

Yup, familiar with their work.

They give estimates… of 2-3k spread.

You cannot grit rate a natural stone, they were made by nature, over hundreds of thousands of years, there was no quality control.

Another stone I recently purchased from the U.K. (Most likely the last honing stone I am going to purchase.)



The top surface of the stone showed no obvious signs to its origin.



But the underside was quite different, and the primary reason I chose to bid on this stone. The grain pattern indicated a natural stone, and not a man made stone.



Flat sanding with 220, followed by 400 grit w & d, highlighted it as being a quick release slurry stone, of a soft to medium hardness. The swirly grain pattern was now much more obvious to see after a light spray of water.



The next photo shows the sedimentary layering within the stones side grain.



Additional information;

Dimensions; 20.1 cm x 5.3 cm x 2.5 cm. (266 cm3)

Weight; 740 grams.

Specific Gravity (SF) = 2.78

Conclusion; the stone appears to be a highly featured Scotch Dalmore Blue. Possibly better suited to water as a lubricant than thin oil. A quick release slurry stone, suggesting a fast cutting stone. A high range in SF, indicating a large % of fine particles within its make up.

I would rate this as a high value/ high quality honing stone, purchased at a remarkably cheap price.

StewieS.