Another whats under the stone post.

[swagman]

Received this 2nd hand natural sharpening stone from the U.K this morning.

Under all that old oil and grime there are features that indicate its most likely crystaline novaculite in structure, an oil stone, either Washita or Arkansas.



The same stone after being flattened reveals much more of the stones natural features.



During the flattening process, indications are, its a hard stone, slow slurry releasing, most likely pointing to its identity as being Arkansas.

To validate that fact, requires some mathematics to work out the stones specific gravity. (SG)

Weight of the stone = 515 grams.

Mass ( 20.1 cm x 4.7cm x 2.3cm) = 217.28 cm3

515/ 217.28 = 2.37 g/cm3

SG = 2.37.

Using the following site as a reference; http://www.danswhetstone.com/stone_grades_101.htm.

It identifies the stone as being within the Hard Arkansas range of 2.30 - 2.45 SG / 800 - 1000 grit.

Stewie;

 

[swagman]

A few comments on the sharpening box that the stone was made for. Its stamped J.SMITH. The wood chosen looks to be English Rosewood so that was good choice. The mortising out was done to a high standard using a brace and bit, followed by chiseling out of the waste, and further refined by the use of a router plane to true the depth of the mortise floors, (missing the spacer blocks). A beveled edge was then applied to the top lid of the box, as well as the outer edges of the internal mating surfaces. Dowel feet were recessed under the base of the box, and then glued and trimmed off to a 1/8" elevation. The only criticism of J.SMITH, is that he could have taken a little more care to avoid, or address the tear out that's quite evident on the top primary surface of the lid. That being the show piece of the box itself. Was J.SMITH a Carpenter, a Joiner, a Carpenter and Joiner, or a Cabinet Maker. The passing of time will likely suggest we will never find out.

Stewie;

 

[custard]

The wood chosen looks to be English Rosewood so that was good choice.

I wish! But we don't really have the climate for Rosewood.

 

[swagman]

The reference chart I used to determine the grit size of this stone is based on the U.S ( ANSI ) Standard. http://www.danswhetstone.com/stone_grades_101.htm

To compare (ANSI) to the Japanese (JIS) Standard, I came across the following conversion chart. https://www.fine-tools.com/G10019.html

 

[MIGNAL]

Laburnum. I think that's the nearest we get to rosewood.

 

[D_W]

You're on a real bender, Stewie. I've stopped buying stones, so they should be a little cheaper for you to get.

 

[swagman]

DW; I have 1 more stone on its way from the U.K. . No plans to purchase any more as its an overly expensive hobby, and impractical to have too many stones in the workshop. The main reason I started this journey was to better understand the benefits these earlier mined stones can still offer todays woodworker. I am unsure natural stones will continue to see much favour in the future, as there is a continual ongoing trend by modern woodworkers towards man made ceramic stones, and harder and harder alloy steels by the tool manufacturers.

Stewie;

 

[swagman]

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.

Stewie;

 

[swagman]

Having had more opportunity to better understand the design of this sharpening box has lead to me to believe that a spacer block may not have been intended within this box design. Bearing in mind that the mortising out within the bottom half of this box is longer than the stone by 3/4s of an inch along its length. The stone itself can only be fitted, starting from 1 end of the mortise, regardless of how you try to orientate the stone. The side walls of the mortise have been cut to a tolerance to allow for the natural expansion of the wood allowing for seasonal movement. But as you get to the approach the last 1/2" of the mortise length, the side walls begin to taper slightly to a locked fit. In practice, you would install the stone from the non tapered end, then push the stone forward so that it locks in place with just under 1/4" of mortise remaining. To then release the stone, the stone is then pushed towards the non tapered end. If that was the intention of the maker, its a rather ingenious design.

Stewie;

 

[bugbear]

The same stone after being flattened reveals much more of the stones natural features.

The pattern/structure/colour of that look more Washita to me; all the Arkansas I've seen are quite homogeneous.

I will gladly defer to our USA-ian friends on this if they chip in - they see a lot more of these than UK/AUS denizens on finite budgets are ever likely to.

BugBear

 

[swagman]

That's okay bb; while your at it you can also question the knowledge base of Danny Kirschman who provided the source on SG identity, to tell the difference between an Ark and a Washita. http://www.danswhetstone.com/whychooseus.htm

regards Stewie;

 

[essexalan]

Must admit I have walked past a number of stones looking like that thinking they were Washitas. Never knew Arks came in that pattern or colour but the SG can't lie can it? I wonder if it could be a hard white Ark given the oven treatment or just badly stained but as long as it performs it does not matter much. Suggest you exchange mass for volume above and I think I would measure the volume using water displacement if I could get one of my Washitas out of the box that is. Very hard to give an objective grit rating to natural stones but they do perform quite well with most steels.
The rosewood box seems to say cabinetmaker who did not know about CBs but we will never know.

 

[swagman]

Hi Essex, point taken on mass vs volume. Not sure I would bother with water displacement given the sharpening stone should have a regular geometric shape to measure.
http://www.harpercollege.edu/tm-ps/chm/ ... solvol.htm

regards Stewie;

 

[swagman]

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).

 

[D_W]

There is some overlap on that chart (washita vs. arkansas). I'm not sure where it came from (as in, if Dan's is the origin, or if someone else is).

Generally, the very soft lilywhite type of washitas are about SG 2.0 or 2.1 and some of the finer ones are up from that a bit past the range that's described by Dan's.

(very soft is relative, that's what pike called them - but soft has more of a meaning of not dense).

There are two separate meanings that people use with washitas - one (the vintage definition) is stones that are from the pike mine that is now closed. The second is the modern meaning of just very low density arkansas stones (that were probably not marketed historically because they're fragile when they are very low density).

I can't tell what the stone is that stewie showed (ark. vs washita), but the best judge is probably how sharp the resulting tool is. Washitas pass the shave test a little easier for a given cutting speed. From what I've been able to tell by buying a bunch of them, washitas from the pike mine have a structure that looks like a matrix with little holes in it. Arkansas stones (which is everything new now, and some of the old) look like the inverse - a bunch of individual particles stuck together.

 

[D_W]

DW; I have 1 more stone on its way from the U.K. . No plans to purchase any more as its an overly expensive hobby, and impractical to have too many stones in the workshop. The main reason I started this journey was to better understand the benefits these earlier mined stones can still offer todays woodworker. I am unsure natural stones will continue to see much favour in the future, as there is a continual ongoing trend by modern woodworkers towards man made ceramic stones, and harder and harder alloy steels by the tool manufacturers.

Stewie;

You're darn right it's expensive, and right that it's impractical, too. But it's fun to go through a few, and when you do that and keep and use the ones that are the best, they're really satisfying.

I've got a washita that is my favorite that came in a carved box and that was used by a carver in a furniture factory. It is a strong cutting stone and cuts strongly no matter how little it's been abraded on the surface, it's bowed on one side because the carver used it along it's thickness for flat tools (the carving tool marks were in the surface for various tools).

They have a ton to offer woodworkers, but they'll never be the stone of choice for instructors just because new students get mixed results with freehand methods, don't really understand the wire edge (thus a stone that doesn't really leave one is easier for them to use) and there's no constant source for the stones.

I have a lot of stones, and without trying to start a fight, I have very few modern synthetics left - the older stones are more practical for day to day work (practical meaning acceptable results and less time spent sharpening, and there is a side benefit that is not practical - the sensory element is nicer with the older natural stones).

 

[bugbear]

...don't really understand the wire edge (thus a stone that doesn't really leave one is easier for them to use).

Ok. I'll bite, even if I live to regret it.

What's to "understand" about a wire edge, apart from the need to remove the damn thing?

BugBear

 

[Trafalgar]

Merlot, anyone?

 

[D_W]

Merlot, anyone?

Surpringly good choice.

 

[D_W]

...don't really understand the wire edge (thus a stone that doesn't really leave one is easier for them to use).

Ok. I'll bite, even if I live to regret it.

What's to "understand" about a wire edge, apart from the need to remove the damn thing?

BugBear

Most of the modern sharpening regimens don't talk about it because they use stones that don't allow much of an organized wire edge to persist after sharpening.