Three New Stones

[Warren Mickley]

There is sort of a one dimensional theory of sharpening which suggests that we can judge the quality of the edge by the grit number of the last medium that worked it. The reality is much more complicated, but this numerical grit theory has led to some odd consequences. One is that it has placed a premium on stones which cut fast. If one 6000 stone cuts faster than another 6000 it must be superior, no matter what kind of surfaces or edge it leaves behind. Thus we have really sharp and harsh stones like Shaptons or diamonds that leave a battered surface instead of more gentle stones that leave a more refined edge for the same grit size.

Another consequence of this simplistic grit theory is that people have struggled to come up with some abrasive that is inherent in strop leather. They cannot accept that the plain leather is doing its job without some hard particles involved. One guy thinks the horses must have silica in their sweat, one guy thinks the horse must have embedded dust when it rolled on the ground, another thinks the tanning chemicals must be doing the job.

A better method of judging edges is to look at the wood surface that the tool leaves behind. At one time Shapton 16K or maybe 15K were widely used at hand tool events. What I noticed was that even freshly sharpened irons yielded a surface on the wood which was not as fine as that from a soft Arkansas stone. Does that mean the soft Arkansas is 20K or something? I think the answer is that the Arkansas is good at polishing, while the Shapton is good at removing material. It was designed to remove material, not to polish edges.

There is a place for stones that remove material in a reasonable amount of time, although too harsh a stone will leave a surface that is more difficult to polish. The Arkansas stones are good at smoothing scratch patterns and polishing. Trying to make them act like Shaptons or diamonds or Besters will diminish their capacity for polishing.

[ken hatch]

There is sort of a one dimensional theory of sharpening which suggests that we can judge the quality of the edge by the grit number of the last medium that worked it. The reality is much more complicated, but this numerical grit theory has led to some odd consequences. One is that it has placed a premium on stones which cut fast. If one 6000 stone cuts faster than another 6000 it must be superior, no matter what kind of surfaces or edge it leaves behind. Thus we have really sharp and harsh stones like Shaptons or diamonds that leave a battered surface instead of more gentle stones that leave a more refined edge for the same grit size.

Another consequence of this simplistic grit theory is that people have struggled to come up with some abrasive that is inherent in strop leather. They cannot accept that the plain leather is doing its job without some hard particles involved. One guy thinks the horses must have silica in their sweat, one guy thinks the horse must have embedded dust when it rolled on the ground, another thinks the tanning chemicals must be doing the job.

A better method of judging edges is to look at the wood surface that the tool leaves behind. At one time Shapton 16K or maybe 15K were widely used at hand tool events. What I noticed was that even freshly sharpened irons yielded a surface on the wood which was not as fine as that from a soft Arkansas stone. Does that mean the soft Arkansas is 20K or something? I think the answer is that the Arkansas is good at polishing, while the Shapton is good at removing material. It was designed to remove material, not to polish edges.

There is a place for stones that remove material in a reasonable amount of time, although too harsh a stone will leave a surface that is more difficult to polish. The Arkansas stones are good at smoothing scratch patterns and polishing. Trying to make them act like Shaptons or diamonds or Besters will diminish their capacity for polishing.

Warren,

Thank you....For years I've said "Shinny ain't necessarily sharp", what matters is the scratch pattern of the iron. To my eye natural stones leave a "better" scratch pattern and a sharper, longer lasting cutting edge. Of course YMMV.

ken

[Patrick Chase]

Will do! There are plenty of great 12's. Bunnahabhain comes to mind, only thing that would trouble me in that regard is that I would no longer be able to lean on my favorite which is lagavulin 16.

Lagavulin... mmm, peat.

[ken hatch]

The third JNat arrived today. A Ohira Suita, from So-san's description it should be coarse for a finishing stone but will make a very good medium set up stone.

The new one is in the middle, BTW I mislabeled the small stone on the right. It is a Shinden Genseki:



Even if I can't use them for a bit, they sure are pretty to look at.

ken

[Brian Holcombe]

Brian,

So you like the smoke and peat, I've several Islay Whisky's in my rotation Including Lagavulin 16 but I've never tried Bunnahabhain 12, a must do. One of my favorite day to day Whisky's is Glenkinchie 12 it is more of a Highland Whisky but with a under taste of peat smoke.

What to me is strange, is MsBubba (should be MsMcBubba ), a native Scott, does not like Whisky but loves Tequila and what is even stranger her Tequila cost more than my 12 and 16 year olds. Go figure.

ken

Hah, that is interesting. Fine Tequila is a bit lost on me, I could try it next to something above average and probably not know the difference. Before you retire try Bunnahabhain 25, sure to change your life. If So hasn't quite ruined you with Jnats that will finish the job.

There is sort of a one dimensional theory of sharpening which suggests that we can judge the quality of the edge by the grit number of the last medium that worked it. The reality is much more complicated, but this numerical grit theory has led to some odd consequences. One is that it has placed a premium on stones which cut fast. If one 6000 stone cuts faster than another 6000 it must be superior, no matter what kind of surfaces or edge it leaves behind. Thus we have really sharp and harsh stones like Shaptons or diamonds that leave a battered surface instead of more gentle stones that leave a more refined edge for the same grit size.

Another consequence of this simplistic grit theory is that people have struggled to come up with some abrasive that is inherent in strop leather. They cannot accept that the plain leather is doing its job without some hard particles involved. One guy thinks the horses must have silica in their sweat, one guy thinks the horse must have embedded dust when it rolled on the ground, another thinks the tanning chemicals must be doing the job.

A better method of judging edges is to look at the wood surface that the tool leaves behind. At one time Shapton 16K or maybe 15K were widely used at hand tool events. What I noticed was that even freshly sharpened irons yielded a surface on the wood which was not as fine as that from a soft Arkansas stone. Does that mean the soft Arkansas is 20K or something? I think the answer is that the Arkansas is good at polishing, while the Shapton is good at removing material. It was designed to remove material, not to polish edges.

There is a place for stones that remove material in a reasonable amount of time, although too harsh a stone will leave a surface that is more difficult to polish. The Arkansas stones are good at smoothing scratch patterns and polishing. Trying to make them act like Shaptons or diamonds or Besters will diminish their capacity for polishing.

What was really eye opening to me when I began with Japanese natural stones (and my continuation into Arkansas stones) is how fine of an edge they leave at their respective 'grit'. I certainly agree that getting caught up in the numbers doesn't show anywhere near the real picture as it's been my experience that natural stones (of which a real grit number of 8000 is about as fine a grit as you can find in natural stones) often produce a much more refined edge than synthetics that are even considered much finer in terms of grit.

[Brian Holcombe]

The third JNat arrived today. A Ohira Suita, from So-san's description it should be coarse for a finishing stone but will make a very good medium set up stone.

The new one is in the middle, BTW I mislabeled the small stone on the right. It is a Shinden Genseki:



Even if I can't use them for a bit, they sure are pretty to look at.

ken

Send them to NJ for a few weeks The Ohira is probably pretty close to my Yaginoshima in terms of finish.

[Patrick Chase]

Warren,

Thank you....For years I've said "Shinny ain't necessarily sharp", what matters is the scratch pattern of the iron. To my eye natural stones leave a "better" scratch pattern and a sharper, longer lasting cutting edge. Of course YMMV.

Natural... you mean like "DNats"?

See the bottom product on that page - it's a "natural", but would likely leave the harshest scratch pattern of all as it's significantly harder and more aggressive than the synthetic diamond used in most plates and pastes.

Seriously, I suspect that your underlying preference is for softer abrasives like Silicon dioxide (as found in both JNats and Arks).

EDIT: Amplex == Norton (both subsidiaries of St Gobain)

[ken hatch]

Send them to NJ for a few weeks The Ohira is probably pretty close to my Yaginoshima in terms of finish.

Brian,

I should, it is killing me to let 'em sit but MsBubba will kill me if I don't.

So said for awhile this Ohira was his normal finish stone. It has already been lacquered and feels ready to go. When I return from Mexico lacquering the sides and bottoms of the other two will be first up.

I'm with you on Tequila, the "good stuff" is only a year old, you might as well be drinking 'shine but she likes it and likes it "neat" so she must be able to tell the difference and as always.... You know the correct response...."Yes dear o' light of my life, whatever you want ".

ken

[ken hatch]

Natural... you mean like "DNats"?

See the bottom product on that page - it's a "natural", but would likely leave the harshest scratch pattern of all as it's significantly harder and more aggressive than the synthetic diamond used in most plates and pastes.

Seriously, I suspect that your underlying preference is for softer abrasives like Silicon dioxide (as found in both JNats and Arks).

EDIT: Amplex == Norton (both subsidiaries of St Gobain)

Damn engineers, I guess that "natural stones" should be "naturally formed stones".

Busted, I like HC steels like O-1 and the Japanese White Paper steels which in turn work better with softer abrasives. Warren said it better than I could, the harder abrasives are good for removing metal, the softer ones are better for polishing.

BTW, I've never really understood the "why" I like HC steel and natural stones until reading some of the replies on some of the sharpening threads. Now I understand, where before the preference was just from experience of what worked to give the best balance between sharpness, longevity, and effort.

ken

[Brian Holcombe]

So likes a medium finisher, which often times that works all the same for me as well. Though I tend to only work the backs with a Nakayama since I dont want them to wear away any quicker.

I just finished the Nakayama in cashew lacquer finally after so long, I had previously only shellacked it. The cashew lacquer is really thick and takes forever to cure, so your probably right to do it now while you can't use the stone.