Thread: Natural Japanese waterstones

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

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.

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

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/ToolRev...p%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

Hi Neil

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

Regards from Perth

Derek

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.

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

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...

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

Originally Posted by yojimbo

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

Originally Posted by derekcohen

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 .

Neil

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

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

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.

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.

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