What is the finest Arkansas Stone? Disagreement from the suppliers

[Andrew Pitonyak]

In this post, I list suppliers opinions from Best, Dan's, and Preyda

https://sawmillcreek.org/showthread.php?276528 and here is the list:

Brand	Type	Density	Grit	Grit	Comment
Preyda	soft	Medium	400	600
Preyda	hard	Fine	600	800
Preyda	hard black	Extra Fine	2000	3000
Preyda	translucent	Ultra Fine	4000	6000
Preyda	surgical black	Extra Ultra Fine	8000	1000
Dan’s	soft	Medium	400	600
Dan’s	hard	Fine	600	800
Dan’s	true hard	Extra Fine	1200	+	Same as Translucent
Dan’s	translucent	Extra Fine	1200	+	Same as true hard
Dan’s	black	Ultra Fine	1200	+
Best	soft		1200		12 micron
Best	hard		1500		10 – 11 micron
Best	Black Surgical		2300	2500	7 – 7.5 micron
Best	translucent		3500	4000	5.5-6 micron

When Dan's says "Black", that seems to correspond to "Surgical" from Best and Preyda. In some of their literature, Best simply uses the term Black.

It gets worse, Dan's and Preyda list 5 stone grades. Best lists 4.

Dan's and Preyda indicate that translucent is before "Surgical".

Best, however, has a different take (opinion).

https://www.danswhetstone.com/inform...ne-grades-101/

https://www.bestsharpeningstones.com...ng-stone-grits

As a reminder, they grade Arkansas stones by looking at the Specific Gravity. Higher is better (in theory). Best lists these numbers:

Soft Arkansas - Specific Gravity 2.22 | 12 micron | .00047" | Grit Equivalent: 1200. The Soft Arkansas is close to the 12 micron lapping film but clearly finer than the 800 grit diamond stone.
Hard Arkansas - Specific Gravity 2.36 | 10-11 micron | .00041" | Grit Equivalent: 1500. It is a little coarser than the 9 micron lapping film but finer than the 12 micron film.
Black Arkansas - Specific Gravity 2.55 | 7-7.5 micron | .00028' | Grit Equivalent: 2300-2500. While the Black Arkansas did have a few larger scratches, overall, it is a little finer than the 9 micron lapping film.
Translucent Arkansas - Specific Gravity 2.53 | 5.5-6 micron | .00023' | Grit Equivalent: 3500-4000. It is clearly finer than the Black Arkansas. Most closely resembles the 5 micron lapping film.

Dan's lists their lasts three stones as having a specific gravity of 2.55+ and states that their Black (surgical black) is the finest.

If you look at Best, They show that their Black has a higher density than their translucent, but, then they show high resolution images of the scratch pattern from their Black compared to their Translucent Arkansas. Best claims to base their grit equivalent (micron equivalent) based on comparing the scratch pattern to graded abrasives. Their result is that the Translucent has the "finer" edge.

If you are still with me, I had some general assumptions.

1. Any stone from any supplier will have variations, so, from the same supplier, I expect that I will find stones that will produce results that are out of order, especially for their finest stones.
2. Some kind of consistency between suppliers based on grading. For example, if Translucent usually produces the finer edge from one supplier, I would expect that from another.

Dan's directly states that the specific gravity is pretty much the same for their finest three stones and that stones #2 and #3 are essentially equivalent. In other words, no reason to buy their Translucent because it should produce the same edge as their "true black". But buy their black because it will produce the finest edge.

Best states that although the Translucent does NOT have the highest specific gravity, the produced scratch patterns are smaller.

I have been focused on finishing a project and shop clean-up lately.... and I am not sure if my current skills will allow me to obviously state which produces the finer edge and I do not have the tools to check patterns. part of this is strictly academic I suppose, but I have some practical uses.

I own tools specifically designed to sharpen knives, probably more than is reasonable. I have a few knives that resisted a sharp edge off one of my belt sander knife sharpeners, but after proper rehabilitation with the belt sander sharpener, it took a wicked edge off the Arkansas stones. For the record, I do not shape, repair, or restore edges with the Arkansas stones.

So, any opinions on (surgical) black versus Translucent? (especially with respect to different suppliers).

[Jim Koepke]

[edited]
As a reminder, they grade Arkansas stones by looking at the Specific Gravity. Higher is better (in theory). Best lists these numbers:

If you look at Best, They show that their Black has a higher density than their translucent, but, then they show high resolution images of the scratch pattern from their Black compared to their Translucent Arkansas. .

Any stone from any supplier will have variations, so, from the same supplier, I expect that I will find stones that will produce results that are out of order, especially for their finest stones.
Some kind of consistency between suppliers based on grading. For example, if Translucent usually produces the finer edge from one supplier, I would expect that from another.

Dan's directly states that the specific gravity is pretty much the same for their finest three stones and that stones #2 and #3 are essentially equivalent. In other words, no reason to buy their Translucent because it should produce the same edge as their "true black". But buy their black because it will produce the finest edge.

Best states that although the Translucent does NOT have the highest specific gravity, the produced scratch patterns are smaller.

So, any opinions on (surgical) black versus Translucent? (especially with respect to different suppliers).

The problem we may have is that mother nature cannot be expected to create all stone formations equally, even if we humans give them the same name. Different mines will have stones with different properties even if they are the same as cataloged by gem & mineral professionals.

My translucent stones from Dan's are not as smooth as one that was purchased at a gem & mineral gathering. The Dan's translucent stones also are more translucent than the one purchase at the gathering.

For me the difference between my rouge rock and my black Arkansas from Dan's is indiscernible by feel on the stones or action at work. In the less worn areas the black stone seems to be a bit more aggressive.

Just a thought, if the specific gravity is supposed to be the determinator of a stone's grit, wouldn't the empirical evidence of 'scratch patterns' counter this claim?

jtk

[Bill White]

In my shop I feel that stones are graded by the seller's view.
I just use what I have, sharpen 'till the item works, and let the result determine the quality.
I don't do surgery, but I do have a Spyderco surgical ceramic for finishing. It was a gift, works like a champ, and I could shave with the resultant edge if I was foolish enough (or drunk).

[ken hatch]

I have a number of oil stones but only from Dan's and Pike/Norton so not a clue about the other suppliers.

Even from the same supplier and from the same class of stone, each stone is slightly different. There are several Dan's Black stones and a Dan's Translucent in my kit. One of the Dan's Black stands out as the best polishing stone I've owned. Lucky for me it is a large stone where the other Blacks are smaller so it is easy to identify. The other Black stones and the Dan's Translucent are basically interchangeable. When you deal with natural stones expect to kiss a few frogs but even the frogs can have a place in your sharpening kit, you just have to figure out where,

Bottom line buy, try, return if you do not like, or find a spot for it in your sharpening kit. I usually find a spot.

ken

[Rafael Herrera]

Check out this pamphlete, https://babel.hathitrust.org/cgi/pt?...iew=2up&seq=12. It describes how the old Pike/Norton company marketed their oilstones, including Arkansas. It seems to me that you're equating stones labeled as "hard" and "fine" as being preferable to the softer stones, or that the softer stones are inferior. As I understand it, these stones had their specific uses, it was not one size fit all. If you want to sharpen chisels and plane irons (made of O1 steel), a Washita seems plenty good to me, since it's what I do. The harder stones were meant for harder steels used by "engravers, watchmakers, die-sinkers, wood and ivory carvers, surgeons, etc." The Washita stone was considered a coarse ston

Keep in mind that these stones started as the sediment of an ancient ocean about 300 million years ago, even before the dinosaurs existed. These sediments turned into rock and that's what these companies mine, it's not an homogeneous rock it varies from place to place. They strive to produce stones within certain parameters, but you're never going to get precise numbers from any company as you do for manufactured stones.

Perhaps someone here with more experience can comment about it, but I think that a super fine, mirror polish, shave your hair, kind of edge on a woodworking tool will wear out soon after it hits the wood, so the focus on translucent and surgical blacks is not very productive, although it can be fun to get these edges.

Rafael

[Nicholas Lawrence]

I have a hard and a black from Dan’s. Before switching to oilstones I used a 1000/8000 combination stone from Norton.

The “hard” is a little more aggressive than the 1000 Norton Waterstone, but not a lot. The black is a lot finer. It does not act anything like what I imagine a 1200 waterstone would feel like.

I have an india for faster removal, but mostly I just use the two From Dan’s.

My sample size is precisely one, so if there is significant variation I am not in a position to comment on it.

[Mel Fulks]

Rafael, The washitas were considered coarse ....for a natural stone. Since it was widely used as only stone ,I don't think
users thought of coarse the same way commonly understood today. The Washitas were graded and "coarse" was a grade.
It was pretty common ,at least into 1960s , for a cheap carborundum type stone to be considered coarse even when it
was a tradesman's only stone. In the mid '60s I worked with a great cabinet maker from Lithiwania who only used a
carborundum stone even when hand planing large banquet tables. I wish I had paid more attention to how he sharpened.
All I remember is grinder and the cheap carbo.

[Adam Cherubini]

The problem we may have is that mother nature cannot be expected to create all stone formations equally, even if we humans give them the same name. Different mines will have stones with different properties even if they are the same as cataloged by gem & mineral professionals.

My translucent stones from Dan's are not as smooth as one that was purchased at a gem & mineral gathering. The Dan's translucent stones also are more translucent than the one purchase at the gathering.

For me the difference between my rouge rock and my black Arkansas from Dan's is indiscernible by feel on the stones or action at work. In the less worn areas the black stone seems to be a bit more aggressive.

Just a thought, if the specific gravity is supposed to be the determinator of a stone's grit, wouldn't the empirical evidence of 'scratch patterns' counter this claim?

jtk

I don’t understand the relationship between specific gravity, essentially density, and cutting ability. Feel like at some point, the stones are so hard, they aren’t really cutting. More burnishing.

FWIW, my finest stone is a translucent Norton I bought from Joel.

[Rafael Herrera]

Mel, yes, that's how the washita is described in the pamphlet above, a stone to be used by itself for blade maintenance, assuming you didn't have to remove chips or re-bevel. I remember my dad using a double sided 6" fine/coarse carborundum stone for all his sharpening, his chisels were sharp. I don't remember him using natural stones. I also didn't pay attention either, he didn't really teach me, these are boyhood memories of me watching him work. I don't know if he would have cared for all the types of oilstones, he would have been more excited about trying new woods or figuring out how to build a particular piece out of a picture when he came to visit me when he was still around.
Raf

[Tom M King]

My "black" stone, an early '70's from Smith's, is about comparable to between a 6k and 10k Sigma waterstone. It's much finer, and puts on a sharper edge, than the mid '90's black stone from Dan's. That stone is not any finer than the 6k Sigma. I have, and use all those stones, and have a lot of experience with them, but it's still just my view on them.

I always thought it strange that the Smith's black was so uniformly black for a natural stone. I had never washed it, for probably four decades of use, but at some point not long ago (some few years), I decided to clean them all. I used carburetor cleaner. All the "black" came out of that old Smith's black stone, and it is definitely translucent. Held in front of a light bulb, you can see the light transmitted. They had coated it with some sort of dye. It's a great stone.

These are the only "black" stones I have any experience with in my hands, and under my tools.

All the old guys that worked for me back in my early days in the '70's, and 80's also used nothing more than a carborundum stone, and did fine work with the tools they sharpened with them, but they absolutely marveled at the edge my Smith's Arkansas stones produced, and never used their old ones when mine were available. They did do better work with sharper edges, and I heard them comment on it many times.

[Warren Mickley]

A few notes:
1) You can throw out your grit comparison charts. They were designed to sell waterstones. If you expect a soft Arkansas stone to abrade like a 1000 grit stone you will be sorely disappointed. And if you expect a 1000 grit stone to polish anything like a soft Arkansas stone, you will be disappointed as well.

2) Synthetic stones were first introduced around 150 years ago. Coarse natural stones (rub stones) and medium natural stones (rag stones) were waterstones. Washita stones were not considered coarse except in comparison to other novaculite stones.

3) The various dense Arkansas stones are not very different from each other. It is much more profitable to work on your technique and your discernment, id est your ability to notice subtle differences in edge performance.

[Andrew Pitonyak]

Wow, that was a lot to digest.

I had expected that universally the stones would be graded very similar. They seem to be on the "courser" side, but not on the finer side.

Based one what I read here, not will I probably find stones from the same quarry that differ, but it is natural that different quarries will have different stones with different expected rankings.

I do not consider the finer stones better, it is just that they order the same on the coarser side.

I think that Best does a good job in their description when they discuss how they chose a "grit" with respect to their stones (scratch patterns under magnifications).

I need to read all of that over again. I learned much, but now I need to read it again.

[Andrew Pitonyak]

I don’t understand the relationship between specific gravity, essentially density, and cutting ability. Feel like at some point, the stones are so hard, they aren’t really cutting. More burnishing.

FWIW, my finest stone is a translucent Norton I bought from Joel.

I assume (meaning I am guessing) that a higher density means that either something is packed tighter (less space between whatever so there is more of something), or there is a higher percentage of of something heavy.

I cannot directly comment on burnishing versus cutting, but apparently the Novaculite (Silica Stone) is hard so it can affect (cut) even some pretty hard metals. So, even though I was told by one person that it simply cannot actually cut the metal (so I should use only diamonds for sharpening). I currently believe that to be untrue. I have raised a burr from even the finest stones that I own but I have only tried this on:

• Some old Stanley chisels
• Some newer cheap Stanley chisels
• Modern Case knives
• Some older knives
• Older and modern Buck knives

I bought a knife with some hard super steel just to test it, but it came so sharp I did not bother to do any testing with it yet; figure I will wait until it dulls.

[Andrew Pitonyak]

Just a thought, if the specific gravity is supposed to be the determinator of a stone's grit, wouldn't the empirical evidence of 'scratch patterns' counter this claim?

For certain that is true, and Best specifically notes this difference. Frankly, I preferred how they documented this on their web site compared to other places. Dan's did a good job as well, but, they did not show any tests images. I like pictures!

[Warren Mickley]

For certain that is true, and Best specifically notes this difference. Frankly, I preferred how they documented this on their web site compared to other places. Dan's did a good job as well, but, they did not show any tests images. I like pictures!

Here are some razor edge pictures by Zowada:

Translucent Arkansas
ZowadaTransArkSm.jpg

Shapton 15000
zowShapton15kSm.jpg