Natural Japanese waterstones

[wilburpan]

Studley....it's nice to go above #8000 but there are limited options available. In synthetic waterstones Naniwa go to #12000 and Shapton have #16000 and #30000 and they start getting to be quite expensive, the last costing over $500 for the professional series.

The other option is to go with natural finishing waterstones above #4000 or #6000, but it's a tricky road to go down. I have noticed a few members of this forum have and use them. I have a few and I'm still finding my way with them. There are many pros and cons for going with this option. Is there enough interest from members to start a new 'elementary' discussion on natural Japanese waterstones?

Neil

Thought I'd start a new thread for this. I've been giving natural waterstones a try for a little while now, and I'd like an elementary discussion as well. I figured it would be easier to start a new thread than hope that people pick this up on the fourth page of a chisel edge thread. :wink:

[yojimbo]

Well done, Wilburpan.

Just to start somewhere, I mostly use only natural waterstones. I have a water-cooled Jet grinder -- no heat; waterstone wheel -- and some man--made stones for rough work. But once I've got an edge to where I want it, I much prefer the natural stones. My understanding is that the longer you work the edge, the more the grit compresses, thereby becoming finer. So I have one rough stone (no idea grit comparison, but it cuts about as quickly as my man-made 220 stone, though I'm sure the grit is higher) which I know only as "zebra stone." And a couple of medium and fine stones, though I rarely need the fine if I've cleaned up a blade nicely the first time: a healthy touch-up on the medium (probably around 8000?) and good go on a suede strop with green rouge, and it's in fine fettle.

Becky

[Sheets]

I wanted to be able to go from rough to finish on natural stone. So collected a few of the various stones available (mostly from ebay).
In my opinion, (thus far - am no expert), man-made water stones do a faster job in the rough grits (200ish), faster in the lower mediums (800-1000) and about the same in the finer mediums (1200). These are the man-made grits I have.
I'm still playing around with binsui, iyoto and aoto to see where they seem to fall grit-wise compared to man-made 4000 and 8000. Compounding the problem, of course, is the variation in steels I have amongst various tools (none of them I know for sure what kind of steel - can make an educated guess that chisels are going to be white steel. I have one kanna that is supposed to be tamahagane). I have a variety of fine finish stones, but have still not used them often enough on all the tools to know which work best and when I can go from medium to finish (when its optimum). Regardless, I get my edges sharp eventually.
The natural stones enhance anything visible in the steel, which I like to see.
No question about the best edges from the awase-do, though.

Steve

Stolen from the ground
My tools grinding at the stone
All are worn away

[NeilS]

Ooops - I have also just started a new thread on this topic. As this thread is already underway (by over an hour..apologies, Wilburpan) I will cross link that thread to this one. If you would like to see what I posted, here (http://www.woodworkforums.com/showthread.php?p=810435#post810435) it is.

Neil

[yojimbo]

Neil:

Since yours is the only post so far on the other thread, how about reposting it here? That way we can keep the whole thing in one place?

Regarding your post, as said above, I use natural stones almost exclusively. I took a chunk of money and made some nearly random purchases, and I'm pretty happy with the results. And So is right:
"Using natural stones will enable you to plane thinner (more sheen on the surface of the wood) and at the same time it will make the edge last longer."

That's certainly been my experience. And his explanation supports my (limited) understanding: that the material on the natural stone compresses and gets finer and finer as you sharpen, so that you can achieve with one stone what you would have to use two, maybe three stones to accomplish with man-made.

I've tried to write the names of the stones I buy/have bought on the sides of them -- unfortunately, they're out in my shop right now -- so as to keep some sense of, well, what the hell I'm using... but the truth is I just don't seem to retain it. I just reach for the stones I've learned are best for a given application, and go to work.

It does take time, and a bit more finesse. Most of these stones need careful truing before use, and are very fragile. I bought a hunk of what I referred to in upthread post as a "zebra" stone (all I know of it) -- which is a very effective coarse grit -- and dulled a number of saws cutting it down. Then trued the piece I cut. Within a few days, a crack appeared in the stone. Right across it.

I've reinforced the sides with water-soluble lacquer to try and hold its integrity, which so far is working, but it really is maddening to work so hard to cut the stone, true it, and days later find a crack.

All that complaining aside, now that I've gotten comfortable with these stones, they're my absolute favorites. I tend to use the man-mades on my Western tools, and save the naturals for my Japanese tools.

Not so much because of the like/like factor, but because I tend to sharpen the Western tools with far more haste.

Any of this coherent? Useful?

Ah, well... tired.

[derekcohen]

I have two natural stones. The first I bought about 2 years ago from Carba-tec. It is Chinese rather than Japanese. My experience has been quite negative to date. It is really hard, and I am not sure what it is supposed to be doing! Does anyone here also have one, and if so will you share your experience.

The other is a Japanese waterstone that Lee Valley had (perhaps still have) on a run out sale. It was about $45. I have only just begun using it, but so far my experience is positive - it has a soft feel compared to my Shaptons and hones quickly. I cannot say what grit is but the guys on the Japanese Tools forum speculate that it is about 20000. (if one could measure a natural stone, that is). Wilbur, I know you have one of thse as well. What do you think?

Regards from Perth

Derek

[Sheets]

Hi Derek,

I have two of those LV stones. I've only used the smaller of the two (I can't yet bring myself to erase those lovely stamps on the bigger one) and also really like it. It is fairly soft, but extremely fine grained (probably not the finest available) and puts great edges on my tools.
One of the aspects of natural stone, is the fact that they sometimes have inclusions which are harmful to the steel (areas harder and larger in size than the average grit, so make a nasty scratch). Best way to ensure these elements are either non-existent (no absolute guarantee) or pose a minimum risk, is to buy from someone who knows natural stone (pretty much everyone who has a business selling Japanese tools and such on-line. They either know stones themselves, or obtain their stock from a reputable supplier) or is honest about those that may be more risky or are known to be contaminated to some degree.
I bought two stones off ebay (both from Nakaoka-san [Mifuqwai]) which were el-cheapo because of the (as he describes it) "toxic" flaws. If you want to take the time to locate these toxic areas and remove them (just carefully dig them out to a depth slightly below the surface, same as would be required if a "safe" stone unexpectedly uncovered some) you will be rewarded with a useable finish stone. Of course, the digging out will have to be periodically repeated as the flaws sometimes extend right through the depth of the stone. I don't know how often stones like this will be available, so not necessarily an option. But its definitely worth the higher cost to obtain a natural finish stone and I don't think we will hear of many who don't find the better edge worthwhile.

Steve

[yojimbo]

Hi, Derek,

Steve's information is real good.

I also have an extremely hard waterstone (from Nakaoka-san) -- Japanese, not Chinese -- and I have to say I find it pretty useless except for a really high polish. Really, really high. It refines the edge further (though at that point, I'm just not sure, even given my compulsive nature), but you have to be so careful -- it's very unforgiving -- that it becomes quite tiresome to use. I find I can approach this quality edge by longer work on a lower-grit (still very high) stone.

Yeah, Steve -- what's up with all that gorgeous calligraphy on the stones? It kills me every time I have to lap it off. Sometimes -- usually if I don't have a whole lot of information on the stone -- I'll snap a photo of it for future reference, in case there's some crucial information there I'll need later (hasn't happened yet: just me being compulsive again).

Derek -- the other thing about those super-hard stones is you have to make sure it's abolutely flat, or you'll never get a good feel for where the blade is -- I'm sure you've had my experience of the blade feeling as though it's more skating over the surface than actually being sharpened by it.

Becky

[derekcohen]

Hi Becky and Steve

The only other person I know who has that hard Chinese stone is Philip Marcou (plane builder), and he has been exhorting me to use it as he likes it. So I am curious.

I know what you mean about "flat" being important with hard stones. The last time I flattened it with a 10" Extra Coarse DMT diamond plate. It did not make any difference. I now have a Shapton diamond lapping plate, but I doubt that this is going to do it for me.

What I want to know is whether you use a natural stone, such as the LV finishing stone, after a manmade finishing stone, such as a 8000 or 12000 Shapton, and why?

I suspect that the answer is "grit is not grit when it comes to natural and artificial".

Regards from Perth

Derek

[wilburpan]

Well, here's the rundown of the natural Japanese waterstones I have:

From mifuqwai, on eBay:

Aoto stone: This is a medium stone, probably like a 3000 grit

Okudo Asagi finishing stone - this is really hard, and dark gray in color. It's so dark that I can only tell that it's removing metal by the fact that after I'm done using it, and the water dries up, I see very fine rust colored bits on the black background. I bought this one mainly because it's big.

Ohira finishing stone - I bought this mainly because it was really cheap, since it was about half the size of a small-sized finishing stone. This was my first venture into natural Japanese waterstone, and is also on the hard side, but not as hard as the Okudo stone I have.

From Lee Valley:

One of their closeout finishing stone specials. This is softer, much like what Steve and Derek describe. By the way, it looks like that the closeout specials aren't available any more.

Both the hard and soft finishing stones do a great job on the tools I have. I'm kind of split as to which one I like better. To complicate my life some more, I bought another softer finishing stone from mifuqwai recently -- it hasn't gotten to me yet.

I have a friend that has bought some really high end stones from So at japan-tool.com. I need to find some time to go up to his place and check them out, and see how they compare to my budget specials.

[yojimbo]

I've bought from LV on that close-out special (haven't tried it yet).

Several from Nakaoka-san. A couple from Alex Gilmore (I'm pretty sure...). Some from So.

I also have coarse, medium, fine, and superfine man-made stones.

On the whole, I'm much happier with the edge I get on the natural stones. (Still haven't gotten out to workshop at the same moment I remember to make note of exactly what I have...) I find the edge lasts significantly longer; they need truing less often (except for the coarse grit, which wears down fast); and they impart that (as I've opined before) lovely kasumi haze. Which, of course, has nothing to do with performance (as far as I know -- any opinions?), but is aesthetically really pleasing.

Given the tough work I've subjected many of my nomi to lately, I'd have to say the natural stones give an edge that holds at least -- at least -- twice as long. And, as mentioned here (or was it elsewhere?), I can touch them up very quickly with a suede strop and green rouge (whose idea was that oxymoronic name?).

The man-made stones are fairly durable -- I find they don't need flattening all that often, and are blessedly free of random inclusions. But no matter how fastidiously I work them, I just don't get the same edge in the same amount of time. I have to believe the "the longer you sharpen, the finer the grit" theory of natural stones accounts for this.

The important thing to remember is that 800-8000 grit man-made stones can be stored in water (not good for 220 or 12000, e.g., on the other hand), but the natural stones should really only be wet down slightly, and as needed, during the sharpening process.

On some natural stones (the harder ones, mostly -- which may partly defeat the purpose), I like to use some nagura stone in order to reduce that skating feeling I mentioned before. Just seems like a more solid bond between stone and bevel.

I find I need nagura on almost all man-made stones.

So, yeah, Derek: grit is not grit. And yet, it is: just a constantly diminishing size. I have yet to be able to guess at a comparison between my man-made and natural stone grits.

Any chance So might weigh in on this and enlighten us? Or Alex? (Or is Alex on the other forum? I'm losing my mind -- I mean memory...)

Yours in galloping senility (at a shockingly early age!),
Becky

[Sheets]

Derek,

I have both a 4000 and 8000 man-made stones. But as I understand it, I should be able to go from a "medium" natural stone like iyoto or aoto to a natural finish stone, and that's what I've been doing (with satisfactory results I think). So I suppose my wanting to know how these stones compare to each other grit-wise is just academic. I don't plan on putting the man-made finish stones in play before going to the natural finish stone(s).

Also, with respect to sealing the natural stones, I use Mod Podge (sometimes called Podgey). Its cheap (sold in craft stores and used as an adhesive or sealer top coat on things like paper one wants to waterproof. It dries quickly, but does not form a hard, brittle skin, but rather flexible) and non-toxic. It smells a lot like PVA glue (looks like it too) and can be thinned with water. My binsui stone lost a large chunk along a fault, but I just Pogied it back on and so far, no problem.

Steve

p.s., one thing I've found (as you all probably have) it that too much water on the fine stones causes the blades to skate and slip and chatter (even on the softer stones). A slurry always seems to help, so maybe you guys with the hard stones, you need something to create a slurry (or maybe less water?). I just dip my finger and spread it on a small area (I don't try to wet the whole surface).
Another thing (now that I'm on a roll) that for me ensures an flat bevel (I don't use a guide) is to put the blade on the stone, feel when the bevel is flat and only push it away from me (cutting edge leading of course) for a short distance, not trying to make a continuous stroke down the whole length (regardless of the grit of the stone). I found that trying to extend the stroke too far (arms too far out from the body) imparted either a rocking motion (rounding the bevel) or losing the feel of when the bevel was flat (it could be, but not sure). When I reach the end of my short stroke (happens all the time:~), I completely lift the blade off and don't try to slide it back, even with lighter pressure. Not the world's most efficient sharpening technique, but works for me. I also work across the surface of the stone not only along its length, but diagonally and even perpendicular to the length. Using the short strokes this way helps keep the surface from hollowing (I'm sure it would howl if it could:).
Stay tuned, I'm sure I'll think of something else.

[Sheets]

"green rouge (whose idea was that oxymoronic name?)."

A girl that does wood working and has really nice tools. Great. But green rouge! I mean, really.

I just can't picture it,
Steve

p.s., I am kidding, Becky.

[yojimbo]

Have tried Harrelson Stanley's side-sharpening technique; find it almost impossible: but then, I'm so used to working with the wide edge of the blade parallel to my body, or just slightly skewed.

Like Sheets, I tend to work in small strokes, though on the coarse stone, I'll work in longer strokes toward me to gain even pressure and cut larger amounts of metal. When I get to the finishing stone, I'm much more conservative. Also like Sheets (and who wouldn't like Sheets?), I tend to work the bevel around the surface at all angles and into all corners. Same reason: more even wear on the stone.

When flattening the burr on the back (if I get one -- and sometimes, superstitiously, even if I don't ), I use the long edge of the stone, just in far enough to insure good flat contact.

On a different note, I use the sides and corners of the stones for gouges and parting tools. (Really wish my gouge sharpening technique were better -- any help here?) Not always, but generally. Or I'll cut a piece of a stone and shape it to fit. I have some man-made cones and other shapes, but -- as noted before -- I never feel I have the same excellent contact and results as with the natural stones.

[yojimbo]

Have I fallen so far in your estimation that you must tell me you're kidding in a pathetic attempt to shield yourself from my Wrath? Hang on... fallen... estimation... See, that sentence started off in one direction, then hung a sharp left. Take two: Am I so far fallen in thy estimation that thou now must needs stoop to inform me whence thou art making of me such keen mockery? What sayest thou, Bedsheets?

[Sheets]

Its still one of those days.

It would have been presumptuous of me to assume that making light of the gender link, whilst in no way intended to to be personal, could in any case become personal should you personally attribute such a personal possibility without clarification that such a frivolous reference to your post and your gender in a more or less offhanded way, could, without intention cause hurt or embarrassment which is surely wasn't supposed to do, therefore I felt compelled in a most chivalrous way to state my intention lest there be misunderstanding....what?

Steve

"Humour, to one man
Lightens the heart and the soul
But wounds another"

[NeilS]

I have really appreciated the postings on this topic so far.

OK, here is my experience with natural waterstones, which has some similarities to others.

After using synthetic waterstones for a while (up to #6000) I thought I would try something finer on my Japanese chisels to see what that would do for them.

Rather than going for a finer man-made stone I decided to purchased my first natural waterstone from Woodworker.com in US. One of the few readily available sources at the time. It was an Ikeda Honyama finishing waterstone - a hard stone with irregular natural shape, low abrasion power, fine grit (approx #10,000). It's a dark grey even looking stone, similar in appearance, and probably performance, to Asagi stones. It left me very tepid on the whole natural stone idea. Not really the place to start, and definitely not the next stone to go to after #6000.

After my first, less than satisfactory, experience with natural stones I eventually ventured back into the water again to see if I might get a better outcome by buying from someone with more expertise than an online western tool store. An improvement in the exchange rate on the A$ at that time was also a factor in allowing me to take the next step. Like others, I located Mifuqwai on eBay (Nakaoka-san) and after some challenging email exchanges (my problem, I don't have any Japanese language) I purchased a Nakayama white karasu finishing waterstone, another hard stone, with medium abrasion and a super-fine grit (approx #20,000), with a few (toxic) lines/spots with coarser grit that has to be removed to avoid scratches on the polished surface.

The Nakayama is a good stone in the hands of a highly skilled (and knowledgeable) user, but it was still beyond my skill levels at that stage of my development. I may have given Nakaoka-san an incorrect understanding of my skill level! So it was back to the man-made stones.

Then a new Japanese woodworking tool and stone seller appeared on eBay, and he (Soatoz) was also located in Australia. After some email exchanges with Soatoz, he offered to assess my Nakayama stone. The verdict was (having examined my efforts on the stone) I needed a softer stone to develop my level of expertise. He recommended a few stones, including a Takao. This is a light yellow finishing waterstone - a softer stone, with medium abrasion power and fine grit (approx #16,000). This new stone, along with a new diamond plate for flattening stones and raising a slurry, got me finally going and experiencing what the natural waterstone thing is all about.

At about the same time as I was purchasing the natural waterstones I began to purchase some Japanese hand-forged kitchen knives. These all arrived pre-sharpened to a high level on natural stones and allowed me to experience how sharp and how long a blade edge can last. They were also an excellent way to learn how the different stones work and how to get the best out of them.... those knives have got so much blade to see and work with...and appreciate when you get it right :). I now even prefer the Nakayama for that final 'mist and haze' finish to the knives

So, what do I think now about my nat stones. I can really tell the difference between a #80000 synthetic (I don't have a higher synth) and #16000 or #20000 nat stone on the knives, and I prefer the look. It could be the difference in grit size, but feel its more to do with the variation in grit size... ie the micro serrations... and perhaps the edge compression. I am inclined to take any blade that I hand push (laminated plane blades, paring chisels and carving tools/knives) on to the natural stones...they cut better and longer. I'm not yet convinced about this for my struck chisels or chopping blades, but then I don't have any coarse or medium natural stones that might come into their own with them.

If I had one take home message for anyone who has not yet ventured into natural waterstones it would be to start with a softer stone (say 7/10 or 7.5) with at least medium abrasion power.

Neil

[yojimbo]

Ah. Now that you've so lucidly lucidified, lucidiated, and otherwise lucidatiously, languidly, luxuriously lolled about the (former) English language, I understand. I get it. I grok, man. I... Say what, now?

And just between you and me, your wife tells me you're not averse to a touch of green rouge of a Saturday night yourself, Sheets-to-the-Wind.

And she says you look lovely in it.

:o

[derekcohen]

C'mon Becky, are you inferring that the green rouge clashes with the colour of other tools you own? :U

I do use a "side sharpening" method. Incidentally, Harrelson may use this as if he invented it, but the method has been around a long, long time. I do a mostly-side and also-diagnonal honing, with just a very little front-and-back when freehanding blades.

Harrelson sent me one of his Sharp Skate honing guides for review when they first came out. I think that the concept is good, and it is a good set of "training wheels" for a novice. Where it falls down for me is that it cannot go diagonally.

My review (with side sharpening instructions) is here: http://www.inthewoodshop.com/ToolReviews/Side%20Sharpening%20and%20The%20Sharp%20Skate.html

Steve, interesting what you say about the amount of water you use. One of the reasons I moved from King to Shapton waterstones was, in addition to their reputedly longer flatness and quicker cutting, that they required less water and were, therefore, less messy.

What I found was that honing with just a spritz of water quickly caused the dreaded "sticktion". The stones would become clogged with swarf. Then I watched a DVD of Harrelson demonstrating the side sharpening method (running through every grit under the sun - but that is another issue). What struck me was that he used so much water! As much, if not more, than I had used on the Kings. I tried it, and it really made a huge difference. Gone was the sticktion, and the stones just worked so much faster. For reference, I use the 1000, 5000, 8000 and 12000 (not all the time - I am starting to skip the 8000).

Regards from Perth

Derek

[derekcohen]

Hi Neil

Thanks for that wonderful, detailed report. Our posts crossed or I would have replied as well to you.

Regards from Perth

Derek

[yojimbo]

Hey, Derek:

Nice post -- and great link. I'm inspired -- not to buy Harrelson's guide (too much money for me right now [lots of jobs out; little remuneration in... yet]), but to give the side sharpening a more dedicated attempt. It certainly does make sense -- always did. I just couldn't get comfortable. But I realize now I may have simply given up too soon.

I do use Harrelson's method of removing the burr at each stage, which I find so much more efficient and clean.

Just a note in terms of water for those using natural vs. man-made stones: the finer the grit (or whatever its equivalent), the less water you need or want. You'll find that too much water on a really fine stone will create an annoying and complete absence of friction. Try just a tiny amount of water, or add some nagura stone slurry (anyone yet have an idea if this defeats the purpose? I haven't found it so...).

And Derek: I let nothing clash with my tools. Too many dings in the edges. :rolleyes:

[Sheets]

Derek,

There is a sweet spot amount of water with the natural stone. With man-made, you can sharpen under water if you want to. Too little, and it just dries too fast (or reaches the almost dry mud stage too soon). But too much and as Becky said, the tool hydroplanes and just won't get sharp.
I used to leave the dried slurry on the stone from the last time I used it, but since I don't store the stones in a closed container, I found it too likely that some sort of contaminated dust would end up in it and I'd have to wash it all off anyway, so I do start out each time with a clean stone now.

Steve

[yojimbo]

Same here: I never leave slurry or bits of metal (that I can see, anyway) on the stone. Start with a clean stone every time, and clean it well when I'm done. I also give 'em a rinse before I start (just a good amount of water and a swipe with my hand), in case anything's settled on them while I've been away from them.

Of course, any grown-up would have boxes for them... but that's any grown-up. Not me, dude. That'd make much too much sense.

Okay, I admit it: I'll find/make good boxes for all of them when the workshop's done. Some time in 2013...:~

[derekcohen]

Here are a few interesting contrasts.

I used to clean and flatten my Kings before packing them away at the end of a woodworking session. Then they were ready to go next time.

When I changed to Shaptons I discovered that they moved slightly after drying out. Not much, but enough that flattening them after use was a waste of time. So I just let them dry in a used state, and cleaned and flattened them next time at the start of a woodworking session.

I experimented with one of the Shapton 8000 Professional stones, taking a leaf out of the book for the Shapton glass stones, by epoxying one to a 1/4" piece of glass. This seems to have done the trick. Certainly the stones appear to remain flat now overnight. I have just finished laminating the other Shaptons. So we shall see.

Looking back now I realise that I just took for granted that the Kings were flat because I had flattened them the night before. It would be interesting to check them (I will use them just to test this out), and ditto with your natural stones.

Regards from Perth

Derek

[NeilS]

or add some nagura stone slurry (anyone yet have an idea if this defeats the purpose? I haven't found it so...).

Becky - nagura stone is still a puzzle to me, so I can't make a useful comment. In fact, I was hoping that you, and others, might enlighten me a little on why you use it and, if so, how do you find it helpful.

My only experience of nagura is limited to just the one piece that I obtained from Nakaoka-san, along with my Nakayama stone. When I began to use the Nakayama I was getting some very noticeable scratches on the otherwise very fine polish. At first I assumed it was coming from some minor flaws in the stone, but the problem didn't go away when I removed those.

It was So-san who worked out what was happening - it turned out that the nagura had a lower grit size than the stone I was using it on, which, of course, was self defeating. To get around this So-san suggested I use a diamond plate to raise the slurry on this hard stone... just took a couple of rubs and that sorted the problem.... instant slurry of the same or greater grit size than the stone itself. Thus far I haven't felt the need to go back to the nagura.

What would nagura do that the stone's own slurry does not provide?

Thanks for any help on this.

Neil

[NeilS]

taking a leaf out of the book for the Shapton glass stones, by epoxying one to a 1/4" piece of glass.

Derek - I glue my natural stones to a base, but for a different reason. The undersides are often far from anything that remotely resembles flat. Sticking them to a base makes them more stable in use. A rocking stone is not very helpful in getting that fine touch to an edge..:(

Becky/Steve - I do leave the slurry on my stones when I store them...for me it's valuable stone that I don't like to waste. Should I decide I want a more aggressive cut next time I use them, I will wash them off and start again but more often than not I am only needing a fine touch up anyway and the old slurry is ideal for that. Leaving the and reusing the slurry does mean that I do cover them up for storage, mostly :U.

Neil

[derekcohen]

Hi Neil

The LV natural stone was very rough on the underside, so much so that it rocked all over the show.

I considered epoxying it to glass, but eventually filled in the gaps and levelling it with car body filler (which is epoxy paste). This works extremely well since one can sand the filler nice and flat. The whole thing even looks good.

Regards from Perth

Derek

[Woodjoint]

Hi Derek & all,

I too have one of the LV stones I got on the recommendation from someone on line that had one. I've only had it for a month or so but really appreciate your idea about using Bondo (our version of body filler here in the states) to level out the bottom and also I think add a little strength to the stone as well. I have one other mid grit stone that I used epoxy paint on the sides and bottom to attempt to do the same thing. It was a lot flatter so I didn't need to get it flat just help hold it together as I remember. I don't use it much after getting the Shaptons but my finest is a 8000 King so I wanted to get beyond that. I'm still getting the hang of the new stone so I don't have much input on that at the moment. This is been a very enlighting thread expecially since the Japanese tool forum over here has been really slow as of late. I think everyone has been slowed down after the round of spamming we had there. G'day to all:cool:

[wilburpan]

I'm going to go out on a limb here, but I think I have a decent model/theory as to why natural and man-made waterstones behave the way they do.

This is what I've observed and what I know about natural and man-made waterstones as far as they work on my Japanese tools:

1. Using Shaptons, the tool gets an extremely reflective surface. So much so that on the bevel of a Japanese chisel or plane blade, the lamination line becomes almost invisible because the hard and soft steel layers become so shiny. On the other hand, using a natural Japanese waterstone preserves the different appearance between the hard and soft layers.

2. With natural Japanese waterstones, it does seem to me that as you work on a tool, the grit size changes to a finer grit. I know that others here and elsewhere have found that to be the case.

3. Natural Japanese waterstones will have more variance within the stone than a man-made one.

4. The issues referred to earlier regarding using a Nagura stone on a finishing stone, with the Nagura having a higher grit.

So here's my model, shown as a graph. These graphs show the distribution of particle sizes between a man-made and natural Japanese waterstone, both about 8000 grit. The curve for the man-made waterstone (blue crosses) shows that the particles are much more uniform in size than the natural waterstone (green circle). Even though both waterstones are nominally 8000 grit, the natural Japanese waterstone has a wider range of particle sizes than the man-made one.

But what happens as you use a natural Japanese waterstone is that the grit particles themselves break down as you sharpen. This is represented by the orange squares. As the particles break down, the green circle curve shifts over to a curve centered around a higher grit. I don't think that this happens for the man-made waterstones. There still is more variation in particle size in the natural Japanese waterstone after a period of use than the man-made stone.

To my thinking, this explains a number of things. Certainly this explains the observation that a natural waterstone seems to shift to a higher grit as it gets used.

The difference in the range of particle sizes between natural and man-made waterstones might explain the fact that natural Japanese waterstones preserve the appearance of the hard and soft layers of Japanese tools. If the particles are very uniform, the grooves left after sharpening will be very uniform, leading to increased reflectivity. With a larger range of particle sizes, the grooves will have some degree of randomness in their size, leading to less reflectiveness in the metal.

This variation in particle size could also explain the "stiction" issue that occurs with Shaptons. If the particle size is very uniform, the stone presents a very uniform surface to the tool, which would increase the surface tension of the water (or whatever other attractive force there might be) leading to the stiction effect. With a natural Japanese waterstone, because of the greater variation in particle sizes, it's a somewhat less homogenous surface, leading to less stiction.

Now, I have no evidence that this is what happens, but this model certainly provides a plausible explanation for many of the observations about how man-made and natural Japanese waterstones behave.

[NeilS]

Now, I have no evidence that this is what happens, but this model certainly provides a plausible explanation for many of the observations about how man-made and natural Japanese waterstones behave.

Hi Wilbur - Nor do I have any 'evidence' that this is the case, but believe it to be so from experience.

Deferring to a higher authority, Nakoaka-san (Mifuqwai), and in his own words (I couldn't put it any better if I had to translate it into Japanese):

"Japanese finishing whetstone is said that it reach it than # 12000 as we begin to use it and use it from 3000 #~# 5000.

A grain breaks as I use it and shrinks.

It cannot express grid# by fixation like a man-made stone."

Having said that in our various ways, what, if any, benefits come from this variation in grit size, other than the kasumi (misty) look?

I defer again to a higher authority, So-san:

"Using natural stones will enable you to plane thinner (more sheen on the surface of the wood) and at the same time it will make the edge last longer. This has a good reason. The sharpening particles of the synthetic stones are even in their sizes, whereas the natural one's are not. Therefore blade sharpened by synthetic stone will have even height of serrated teeth, so once those teeth gets dull it stops cutting altogether, but... when the height is different... I think you see my point. It's like the shark's teeth. They don't break all at once.

Also, the natural stone sharpening has a hardening effect on the tip of the blade. This has been proven scientifically by the HRC testing machine experiment done by renowned plane blacksmith Usui Kengo. The hardness was actually harder after being polished by a fine Nakayama stone."

This would have to be the reason why we bother with these tricky stones. When we get it right our blades stay sharper for longer. That's not to discount the aesthetic attraction that some of us feel for the kasumi finish, but I'm not sure I would go to all the extra trouble of nat stones to get that effect... well not on my woodworking tools, but perhaps on my Japanese hand-forged knives that hang on my kitchen wall - so I can admire/enjoy them even when I am not actually using them...:)

Neil

[NeilS]

People following this thread, may also be interested in the comments in a parallel thread on treatment of nat stones, including cutting, sealing and how to manage uneven bases. Relevant comments start at about post 59 ==> here (http://www.woodworkforums.ubeaut.com.au/showthread.php?t=79093&page=4).

Neil

[Pam]

Wilbur, what does the X-axis represent? Time sharpening?

Pam

[yojimbo]

"Using natural stones will enable you to plane thinner (more sheen on the surface of the wood) and at the same time it will make the edge last longer.

... What I've been saying all along. :)

Nice to have something approximating proof that I'm not nuts!

Thanks, guys.

[wilburpan]

Oops - forgot to label the axes. :doh:

X axis = grit number. Y axis = number of particles of that size. Moving to the right on the X axis represents smaller particles.

[Pam]

Thanks, Wilbur. I think there may be a problem in talking about the number of particles since the sharpening process doesn't necessarily increase the number, which is determined by the number of particles temporarily embedded/conjoined as the stone. Do you say this because the process splits each grain?

Pam

[wilburpan]

To my thinking, it's not the absolute number of particles that's important in this model/theory, but the relative distribution of the sizes. The main point I was trying to illustrate is that I think that a man-made waterstone has very uniform particles, while a natural waterstone has less uniform particles, even though the average particle size may be the same between the two. The second point is that as you use the natural waterstone, the particle sizes break down so that they become smaller and somewhat more uniform, which doesn't happen with the man-made stones.

For my illustration, I generated these curves using the function for a normal probability distribution, but I couldn't figure out how to manipulate the curves so that they all peaked at the same height.

In fact, if I understand the math right, each curve represents the same number of particles in total, just distributed in different ways. That's the reason why the skinnier curves peak higher. The area under the curve for all three curves should be the same.

[yojimbo]

Not clear here, by any means, but I'm thinking -- as the particles break down, don't they increase in number? They can't just get smaller: they must fragment. No? After all, matter can neither be created nor destroyed: it can only change in form... as me late, great mum used to tell me whenever I said, "But I can't find it!"

Becky

[wilburpan]

The particles would increase in number as they break down, of course. Again, what I was trying to illustrate was not the absolute number of particles, but how the particle sizes varied for each situation.

[yojimbo]

Hi, Wilburpan --
I should've been more specific. I was responding more to the question Pam raised.

Becky

[Sheets]

Originally Posted by wilburpan
"Now, I have no evidence that this is what happens, but this model certainly provides a plausible explanation for many of the observations about how man-made and natural Japanese waterstones behave."

I tried to to get a pic of the particles pre and post usage. I had them lined up just perfect, but sneezed, and they all got mixed up and I lost a couple (at least). Oh well.

On a less serious note:U I found this on the JWWF (real pics!)
okanna.blogspot.com

I would surmise that there is also a difference between natural stone and man-made in shape at this scale and no doubt the shape affects the cutting action.
I think natural grit is kind of like free range - once its "free", it really feels no compunction to remain as it started out.
(no, I'm not telling you where I live, lest someone sends the guys in the white coats:roll:)

Steve

[Pam]

To my thinking, it's not the absolute number of particles that's important in this model/theory, but the relative distribution of the sizes. The main point I was trying to illustrate is that I think that a man-made waterstone has very uniform particles, while a natural waterstone has less uniform particles, even though the average particle size may be the same between the two. The second point is that as you use the natural waterstone, the particle sizes break down so that they become smaller and somewhat more uniform, which doesn't happen with the man-made stones.

For my illustration, I generated these curves using the function for a normal probability distribution, but I couldn't figure out how to manipulate the curves so that they all peaked at the same height.

In fact, if I understand the math right, each curve represents the same number of particles in total, just distributed in different ways. That's the reason why the skinnier curves peak higher. The area under the curve for all three curves should be the same.

OK. Wilbur, I think the process is a little different: particle breakdown should happen at one point and maintain rather than decreasing. Or, it's not a bell curve process. This is very difficult stuff to model.

Becky, I'm not at all sure we know what's happening here. You think the stone particles break down, get smaller? Right? That's reasonable. But maybe the particles appear smaller because they're separated from the main body. So does the steel increase the number of particles or merely separate them from the "stone?"

Pam

[yojimbo]

My understanding is that the particles "compress" as you use the stone -- which, to me, implies they're being broken down rather than simply released from the stone. Also, just knowing the basic properties of stone, it all breaks down, no? I can't imagine any stone that wouldn't yield its integrity under the repeated stress of metal pressed and compressed against it.

On the other hand -- since I love to argue with myself -- if the stones are what started out as, say river silt, maybe they're already in the smallest possible particles -- except (arguing again with myself:~) the fact that it's a solid, durable stone makes me wonder if this is possible.

Although (:?), since sedimentary rock undergoes compaction (right term?) -- again, we're dealing with compression. If the stones are, in fact, siltstone... which is what I always assumed... then the question is can silt be broken down further than the state in which it formerly existed?

It still seems to me, arguing on an atomic (molecular?!) level, there's nothing in rock particles that couldn't be broken down further through the sharpening process.

Does this mean we're dabbling in atom-splitting? Or is it just hair-splitting? Or maybe it's just my personality splitting: :((:no::oo::cool:.

Becky (and whoever else is in here with me)

[Sheets]

Originally posted by Yojimbo -

"My understanding is that the particles "compress" as you use the stone -- which, to me, implies they're being broken down rather than simply released from the stone. Also, just knowing the basic properties of stone, it all breaks down, no? I can't imagine any stone that wouldn't yield its integrity under the repeated stress of metal pressed and compressed against it.

On the other hand -- since I love to argue with myself.....etc.,"

I think you're both right.

Actually, it makes sense that the particles of stone will abrade themselves as well as the steel. And the steel particles will also abrade the stone and the bevel while they are freshly removed (they will quickly dull and perhaps provide more of a burnish, but certainly less "cutting" action). But even dulled, they must get pushed against the stone particles and help free/crush them (and break up into smaller bits). One of the desired attributes of kamaji is that it contains impurities which help wear the stone and expose fresh (sharp) grit. But this would also ensure grit is released constantly as well, adding to the slurry. Maybe its the depth of the slurry which slows down the rate of cutting (some of the loose grit will just move along and not dig in, in effect making the cutting action less effective but still present and the result is a finer scratch pattern.

On other tangents (worthy of entry to the loony bin no doubt*), can there be some chemical reaction because of the water? (other than straight oxidation - but even that on a near molecular scale must have an effect?)

(*no doubt at all)
And then there's the different types of steel. Maybe with pressure and the abrasion action, the austenite, pearlite, cementite, martensite, and ferrite, get transformed into say, Austenmartin or ferrocement (with the correct pearlcentite of each), etc.?

:Uteve

[yojimbo]

:Uteve:

What a guy!

:2tsup:ecky

[Sheets]

Careful - don't encourage me.:no: I'm sure there are a lot of others too pearlite to tell me stop.

Steve

[yojimbo]

Aaaaaaaaaaaaaaaaaaaarrrrrgggggggggggggggghhhhh!!!

[Sheets]

Its not my fault. Something happened to me when I watched that flying kokeshi doll stool show:o

I'm obviously losing my grit on reality:?

Steve

"I do, I do like green rouge on ham"

OK. Seriously.

I have the following natural awase-do from Nakaoka-san: Shinden suita and Ozaki ShouhonzanShinso (Sogoro) Tomae. Both have toxic elements (good price).
Also two from LV Tools - one is Narutaki, can't remember the other (lost the label and ground off the stamps).

Also have an omura, binsui, aoto and iyoto. Plus natural nagura (from LV Tools a few years back).

[yojimbo]

I, on the other hand, am too addlepated to remember, ever, to make note of what I have: only think of it when I'm here.

But list forthcoming... I promise.

Steve -- so sorry about flying fotobuquet brain injury... feel free to contact my attorney at 1-(800)-NO WAY2.

B

[Sheets]

I tried that number, but I was put on hold and told, although my call was valuable, I was number 47 in line. No way, I'm not that bad. Besides, I think the flying kokeshis might just take off and then you'll be too rich for me to litigate.

Steve

On the upside, the latest phones have voice recognition so I can still make calls in a straight jacket.:cool:

[NeilS]

Hi Wilbur/Becky/Pam/Steve – Re particle size/number discussion.

I thought Wilbur’s graphic was very useful in illustrating the difference between synthetic and natural stones. The more I look at that graph in comparison with what I understand the more accurate I think it is, including the increased number of particles pre and post use.

I do, however, have a couple of qualifiers. Perhaps obvious, but worth stating, the ‘used natural stone’ line on the graph only represent the ‘free’ particles suspended in the slurry + , to a lesser extent, the particles in the very thin top surface layer of the stone. In relation to the latter, I think that the particles only partly break down in situ and are more likely to separate away from the body of the stone as larger particles before breaking down into smaller particles as they are worked in the slurry. If I am right about this last point it has implications for how we use natural stones.

Second point, pedantic I must admit, there must be some breakdown in particle size with synthetic stones but perhaps not significant enough to be represented on the graph or taken into account in our discussions.

Back to the increasing number of particles created with use - I am not sure that it’s anywhere near as important as the shift in grit size, but my two cents worth on that discussion is that if any particle is broken down into two or more smaller particles there has to be less of that size particle and twice the number, or more, smaller particles. If anything, the ‘after use’ line should peak many times higher than the before use line. We are not talking here about the stone as a whole (just the slurry + top micron or so of the stone) nor conservation of matter or volume, just how many particles there are in each grit size.

So, are there any advantages in the up-shift in grit size during use? Yes, if you start with a clean stone and want to go in one session from fine to superfine polish on the one stone. No, if you leave the slurry on the stone from last use and are not ready for the superfine polish stage.

If I am right about most of the breakdown in particle size occurring in the slurry phase then the initial creation of the slurry with a diamond plate should enhance this process.

Neil

[NeilS]

On other tangents (worthy of entry to the loony bin no doubt*), can there be some chemical reaction because of the water? (other than straight oxidation - but even that on a near molecular scale must have an effect?)


Not sure about a chemical reaction, but the water does soften the bonding component of the matrix to release the harder grit particles. I think I am right in saying that this is what waterstones do. It's also the reason I don't store my natural stones in water.

On the mechanical process of particle release, I visual it more like a road grader running its blade over the surface of the stone rather than a road roller crushing down the particles of stone, although there is probably both effects. The grader drags out any large lose rocks from the road surface while those that remain embedded provide the most aggressive and long deep cuts. Once released, these particles are tumbled around in the slurry knocking against each other, the base stone and tool to progressively break down into smaller particles like they would in a pestle and mortar (changed metaphor :?). In the 'free' state the grit particles are also less aggressive and create a different abrasion pattern as they tumble and slide between the tool and hard stone....maybe.

Neil

[wilburpan]

Second point, pedantic I must admit, there must be some breakdown in particle size with synthetic stones but perhaps not significant enough to be represented on the graph or taken into account in our discussions.

There were two reasons for my thinking this as I was working this through. First, to my understanding, the particles in the man-made stones were ceramic, as opposed to the natural waterstones, which are sedimentary in nature. Second, to my knowledge, no one has ever reported this feeling that the grit size gets smaller with use with any man-made stone. There are other man-made substances that do have this behavior, the most familiar of which to members of this forum is probably the use of carbide particles on a kanaban.

[RusselBaldridge]

I have stones from many of the usual supliers, and am working with So-san currently (one of those indescribably fine stones that he has tucked away). I agree with pretty much everything that's been concluded thus far, excellent discussion! :2tsup:

I should say that the stones that I got from Nakaoka-san were a little disapointing as compared to the images he provides. They all work pretty well (Aoto, Iyoto, Narutaki), so I can't complain too much, but it should be noted that there are other supliers who have a more "user friendly" approach.

As for the nagura, I find that a good diamond plate accomplishes everything that the nagura does, without the problem of mixing grits. And on top pf that it keeps the stone flat as well, two birds with one stone... er... bad joke, sorry. :)

[NeilS]

There were two reasons for my thinking this as I was working this through. First, to my understanding, the particles in the man-made stones were ceramic, as opposed to the natural waterstones, which are sedimentary in nature. Second, to my knowledge, no one has ever reported this feeling that the grit size gets smaller with use with any man-made stone. There are other man-made substances that do have this behavior, the most familiar of which to members of this forum is probably the use of carbide particles on a kanaban.

Wilbur - It's not a major effect in man-made waterstones, nor worth much comment, but I believe it is there. I can think of two plane makers (Terry Gordon and Ron Hock) who recommend starving man-made waterstones of water to get a final finer polish on the blade. Here is a quote from the Hock notes:

"FINAL SMOOTHING. The second part of this process is to do a final smoothing on the 1000-grit stone. This is the same as the first step, just don't rinse the stone. Instead, let a "slurry" of particles collect on the surface of the stone as you hone.

This "slurry" is sort of a mud made up of broken fragments from the waterstone. Since these fragments are small, they produce a finer finish than working on a clean, freshly-rinsed waterstone." http://www.hocktools.com/sharpen2.htm

But, as I have said, it's a minor effect that that is worth noting but otherwise can be ignored in this discussion.

Neil

[Pam]

...Does this mean we're dabbling in atom-splitting? Or is it just hair-splitting? Or maybe it's just my personality splitting: :((:no::oo::cool:.

Becky (and whoever else is in here with me)

Yeah, I have a strong governor, too. :) I think it means we haven't sufficiently identified the issues. I prefer to think of stones as sedimentary, built from silt and compacted by more silt on top; therefore, all we can do is separate the silt, reverse the process.

Pam

[Sheets]

These stones, while sedimentary in origin, are really much more changed than just their original, uncompacted/uncompressed material. Time (eons) and the great pressure of million tons of material piled up on top and tectonic shifting causing further pressure can morph stone into a form almost completely, if not completely (in many cases) different than the layers of genesis silt. Interaction between the elements (water of various degrees of ph, metals, air, climate, etc.) results in a molecular structure which, in our case (focussing on natural whetstone) can't simply return to its original state (not by mechanical means alone). So, no matter how small the particles of stone become as they get released from whatever structure cements them together, they are still, molecularly, unchanged.
Now, this brings me back to my point about the water. Added to the mix, does it make some sort of chemical soup with the constituents of the stone (and O2, CO2 in the air) and the steel (iron and carbon) which might cause a chemical (molecular) change which affects the steel, even if on a small scale?
:?

Steve

[RusselBaldridge]

Sheets, I can see that being somewhat valid.

The Japanese stones seem to have an affect thats similar to etching on steel (damascus patterns and general lamination lines are brought out) which would imply some kind of ph difference, but that would be easily measurable. I'll try to remember to litmus test the slurry from my stones next time I use them.

Could there be another reason the Japanese stones bring out lamination lines when man-made stones do not?

[NeilS]

These stones, while sedimentary in origin,

..snip...
.
Now, this brings me back to my point about the water. Added to the mix, does it make some sort of chemical soup with the constituents of the stone (and O2, CO2 in the air) and the steel (iron and carbon) which might cause a chemical (molecular) change which affects the steel, even if on a small scale?


Steve - Not quite sure what affects you had in mind....like, make the steel rusty?... or did I miss that in one of your earlier posts?

On the sedimentary origins, as we know the composition of the stones vary widely depending on the mine and stratum. At the coarse end, stones are little more than sandstone, and at the other end are the fine finishing stones from deep strata comprising mainly quartz/silica shales (basically metamorphosised silt clays). Here are more details from So-san if anyone wants to follow up on that:

http://www.geocities.com/soatoz/tech_knlg/toishi/Awasedo.html

Casting my mind back to my days in ceramics, once a clay is fully metamorphosised(through pressure and/or heat) you can't reverse the process by just dissolving it again in water. From my limited experience of natural waterstones, it seems to me that the super-hard stones are fully metamorphosised and will remain that way even if you leave them in a bucket of water for all of eternity. On the other hand my softer stone feels like it has not fully metamorphosised...the bonds are weaker. The slurry forms quickly and feels a bit clay like (ie slippery) and I expect that it wouldn't take too kindly to being left in a bucket of water for any length of time. So, the particle breakdown is mainly mechanical but perhaps aided by the weakening of molecular bonds in water of some 'softer' stones.

Not sure if any of that is adding anything to anyone's thinking on the subject or just stating the bleating obvious.

Neil

[yojimbo]

Neil -- (and Sheets, Pam, Russell, Wilburpan) --

What you say makes sense (effects of storing coarse vs. fine stones in water), and clarifies (?) to me the fact that in that sedimentary rock you have layers of silt in differing phases of compression. I assume that the fine stones are from the deepest strata, and have gradually undergone such compaction that all air, larger inclusions, and even the minute pockets left between individual grains of silt have all been squeezed out through compaction.

The more coarse stones (the better of which have very few visible inclusions), still retain the open shape of the original, larger silt because they haven't be compacted as much. I have a zebra stone in which you can actually see the open structure (or, rather, I should say, get the impression of its open structure) when looking at a flattened face. It's quite aggressive, but breaks down fairly fast and needs flattening often -- sometimes, though rarely, during the course of correcting a single blade.

The thing is, I still can't make logic out of the thought that, aside from the massive compaction, the substance of the stone has changed at all -- assuming there's been no particular heat in the process.

So I'm kind of with Pam on this -- that what we are doing is basically returning the stone to its original silt-like state. After all, what is the slurry but a thickened silt soup? (Cue Steve for raging series of unappetizing puns.)

Am I missing something?

[NeilS]

The thing is, I still can't make logic out of the thought that, aside from the massive compaction, the substance of the stone has changed at all -- assuming there's been no particular heat in the process.


Becky

Yep, plenty of heat in the volcanic and tectonic (think earthquakes) geology of Japan.

Pressure + Heat = Irreversible Metamorphic Change in crystalline structure of sedimentary deposits, the heat being the most important factor in the process. The deeper the stratum the greater the heat and pressure and the more complete the metamorphic change.

Although the chemical composition of the sediments are retained, the mineral properties are irreversibly changed. Think of the chemical carbon, from which both soot and diamonds are made. Same chemical, different crystalline structures and minerals.

Hope that makes the process I was referring to clearer.

Neil

[Sheets]

Neil said:

Yep, plenty of heat in the volcanic and tectonic (think earthquakes) geology of Japan.

Pressure + Heat = Irreversible Metamorphic Change in crystalline structure of sedimentary deposits, the heat being the most important factor in the process. The deeper the stratum the greater the heat and pressure and the more complete the metamorphic change.

Heat write. I mean he's right (must have had a hair on my tongue). I neglected to mention (shouldn't have assumed that everyone would realize that heat was a major factor in the metamorphosis process).

My feeling, Neil, is like what Russel said about etching steel. If there is an acidic element to the slurry (because the breakdown and exposure of the stone into its grit + bonding material. Water can and does produce acid when mixed with certain kinds of rock - sometimes a big problem in the mining industry. And we all know what scotch on the rocks can do). Now, obviously this would be on a very mild scale, but when we are talking about the size of the scratch pattern with grit in the micron size, even a slight action would (I believe) have an effect.
I'm sure we've all noticed when pausing for some reason during sharpening, even after a few seconds, sometimes the blade gets a thin layer of oxidation. No problem because it is thin and readily comes off. But think about that thin (a few microns) layer. We know what thick layers of corrosion do to metal (takes more time to happen), but when we remove that corrosion, we are removing steel originally part of the tool (as evidenced by the pitted, uneven surface beneath). Now oxidation and acid etching (or whatever might best describe any such process) are likely quite separate reactions, but again, looking at depths of a few microns (perhaps equal to the size of the grit particles in play) and there could be enough happening that we "feel" it, even if we can't see or prove it.
I may be out to lunch (and having missed breakfast, really need sustenance - or is it just a "feeling"?)

Hey Russel, I'm interested in your litmus test (I thought of that, but don't have any litmus paper and I ate all my red cabbage a while back). So, please do if you can (we might as well be thorough).

Steve

p.s., silt soup - never tried that. Also, going back a bit (stuck in the silt so to speak), much of the original stuff you guys think of as silt (organic matter, elemental iron, bits of already existing rock, ash - mostly volcanic - which when originally released was probably quite euphoric, but having been whisked about on the breeze for who knows how long, well starts to feel like we're all just....)
So all this silt way back when before the big crush, would be just mud (looks like mud, feels like mud, smells like mud and tastes like silt soup - glad I didn't step in it).
But when its all squished tight, the water gets squeezed out (or absorbed as hydrogen and oxygen combine with other stuff to form other stuff) the great heat (enough to melt rock sometimes) transforms anything thats transformable into something else. A lot changes too.
Anyway, this is probably all too elementary and boring, so I won't toy with its current concept and risk it turning all to gibberish.

Oh yes, before I go, Becky asked for punthing. Are they really unappetizing? Well I wanted tibia a stand up comic, but fell and broke my humerus. Come on now, don't be groan ups.

[yojimbo]

Ah... I get it. Hadn't factored in heat that way: was thinking only of sedimentation and compression... forgot about Japan's formidable and volatile geography.

Thanks for making that so perfectly clear.

Becky

p.s. No, Steve, they're not unappetizing (though quite foul)... that's just jealousy on my part. But I'll deny ever having said it.

b

[NeilS]

My feeling, Neil, is like what Russel said about etching steel. If there is an acidic element to the slurry (because the breakdown and exposure of the stone into its grit + bonding material. Water can and does produce acid when mixed with certain kinds of rock - sometimes a big problem in the mining industry. And we all know what scotch on the rocks can do). Now, obviously this would be on a very mild scale, but when we are talking about the size of the scratch pattern with grit in the micron size, even a slight action would (I believe) have an effect.

...snip...

Hey Russel, I'm interested in your litmus test (I thought of that, but don't have any litmus paper and I ate all my red cabbage a while back). So, please do if you can (we might as well be thorough).

Steve - You could be right about an acidic effect. As original sediments can be either acid or alkali, and given that metamorphic process doesn't destroy the chemical composition of resulting stone, an acid slurry is a possibility.

Like you, I will be interested to see if Russel can take a pH breading and let us know the results.

Neil

[Sheets]

I may beat Russel to it. I got a red cabbage, so can (and did) make some home-made litmus paper. Haven't got to the acid test yet, though. But I'm starting to feel like I'm barking up the wrong tree.
One would have thought that after all these years, the Japanese would have figured it out and built a tradition based on this effect. But will see what the science says anyway.

Steve

[wilburpan]

I'll be interested in seeing if there is any significant pH change, but I'll be pretty surprised if there is. Acid is used to re-etch files and rasps, so it is clear that acid can help sharpen an edge on a tool. But the process for this is fairly lengthy, on the order of 12-24 hours.

Given the relatively short exposure time of the tool to the water on the waterstone, it would have to be a pretty strong acid to make an impact on the metal of the tool being sharpened, and I don't think that hydrochloric acid, or some similarly strong acid, is released as a waterstone gets wet.

[Sheets]

None, nada, nil, zilch. I couldn't detect any ph change on any of my natural stones (not really surprised). I did test my paper before hand to make sure it would show a colour change in the presence of acid (lime juice, grape juice and vinegar). So I think its safe to list list theory as BUSTED:(
Any other bright ideas out there?

Steve

[NeilS]

None, nada, nil, zilch. I couldn't detect any ph change ...snip....So I think its safe to list list theory as BUSTED:(
Any other bright ideas out there?

Steve - am I right in thinking that what you are trying to understand is why natural stones are better at highlighting the difference between the soft iron (jigane) and hard steel (higane), or am I off on a tangent on this one? The original question has become a little blurred for me going back in the origins of this thread.

According to one expert (Alex), there is not an obvious scientific explanation:

"The scratch marks left by the man-made synthetic stones look deep and long when compared to the scratches left by the natural stones. This is typical of synthetic stones which are formulated to cut aggressively and fast. The hard cutting compounds, usually a proprietary ceramic or oxide of some form, do not break down into smaller particles as readily as the organic compounds do in the natural stones. The synthetic stones tend to leave the soft iron or jigane looking scarred under magnification, but when viewed with the naked eye the hagane and jigane look equally shiny. I do not have a scientific explanation for this phenomenon. Natural awase toishi tend to leave the finished blade with more contrast between the hard steel and the soft iron." http://thejapanblade.com/


Alex also provides a very helpful explanation of the sharpening process in relation to man-made, natural and nagura stones. The site is a bit confusing in its navigation, so here is the direct link: http://thejapanblade.com/nagura_use.htm (http://thejapanblade.com/nagura_use.htm)


Neil

[Sheets]

Hi Neil,

I've seen Alex's site (makes me weep to see those stones he has).

The original question someone asked was why natural finishing stones seem to be able to impart such a markedly superior edge (sharper and stay sharp longer) on Japanese tools as compared to man made stones. Finer grit was one aspect, but the feeling people have that there is something else beyond that, was what we were trying to investigate.
The fact that the ha and ji are so well differentiated is another point of mystery, but not part of the original question as I recall. My feeling (guess) on this is that the natural stone has a larger range of particle (size still all very fine) and this makes the softer steel less reflective (the scratch pattern is less uniform, so light reflects differently than a more constant surface).

Steve

[NeilS]

The original question someone asked was why natural finishing stones seem to be able to impart such a markedly superior edge (sharper and stay sharp longer) on Japanese tools as compared to man made stones. Finer grit was one aspect, but the feeling people have that there is something else beyond that, was what we were trying to investigate.
The fact that the ha and ji are so well differentiated is another point of mystery, but not part of the original question as I recall. My feeling (guess) on this is that the natural stone has a larger range of particle (size still all very fine) and this makes the softer steel less reflective (the scratch pattern is less uniform, so light reflects differently than a more constant surface).

OK, Steve, I'm back on the same page.

I think you have as good an explanation as I can come up for the differentiation in Ji/Ha appearance.

On the sharper for longer question, unless a new theory/evidence comes to light, the explanation I lean towards is the variation in fine grit sizes that develops as the natural stone is worked. The mix of grit sizes creates a micro-serrated edge that exposes fresh sharp cutting 'peaks' as adjacent 'peaks' wear/break away. Although not visible with the naked eye, this micro-serration effect is readily felt when slicing with a hand-forged Japanese kitchen knife that has been sharpened on a natural stone (rather than a man-made stone). For example, ripe tomatoes can be sliced paper thin - i.e. if you ever wanted to do that :) and the edges do stay sharp for ages, well until some uncouth person starts chopping instead of slicing food with them :o.

Neil

[NeilS]

..... I purchased a Nakayama white karasu finishing waterstone, another hard stone, with medium abrasion and a super-fine grit (approx #20,000), with a few (toxic) lines/spots with coarser grit that has to be removed to avoid scratches on the polished surface.

The Nakayama is a good stone in the hands of a highly skilled (and knowledgeable) user, but it was still beyond my skill levels at that stage of my development. I may have given Nakaoka-san an incorrect understanding of my skill level! So it was back to the man-made stones.

Then a new Japanese woodworking tool and stone seller appeared on eBay, and he (Soatoz) was also located in Australia. After some email exchanges with Soatoz, he offered to assess my Nakayama stone. The verdict was (having examined my efforts on the stone) I needed a softer stone to develop my level of expertise. He recommended a few stones, including a Takao. This is a light yellow finishing waterstone - a softer stone, with medium abrasion power and fine grit (approx #16,000). This new stone, along with a new diamond plate for flattening stones and raising a slurry, got me finally going and experiencing what the natural waterstone thing is all about.




Visited this thread again after just posting to the thread by Thumbsucker on waterstone hardness, and thought I should do a brief update.

After using the Takao regularly for some time I went back to my Nakayam to suddenly find that it had improved no end. Not sure how it did that just sitting there in its box doing nothing for so long...:rolleyes:

Anyway, its now my go to stone for the final polish and I like it a lot. And to think I almost gave up on it and even considered selling it at one stage.

The Takao has now been repatriated to the kitchen where it does an excellent job on the my hard (blue) steel edge Japanese knives.

So, if you end up with a natural stone that doesn't work for you immediately, put it away for a while and it might magically improve while you are ignoring it...:U

.....