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Nubatama stones

Mon Jun 17, 2013 3:37 am

I want to buy some Nubatama stones, but I don't know the difference between the Ume and the Bamboo series, can anybody tell me the difference?.

Re: Nubatama stones

Mon Jun 17, 2013 7:29 am

Ume 1,000 = awesome

Can't help otherwise. :)

Re: Nubatama stones

Mon Jun 17, 2013 10:26 am

I am willing to bet Ken is going to say a few things here :)

However, from a customer user perspective, I can tell you that I like my Nubatama Ume 1K Extra Extra Hard. If you can get that, get it for the simple reason that there is no other stone like it out there.

wm_crash, the friendly hooligan

Re: Nubatama stones

Mon Jun 17, 2013 11:29 am

I have some of both and they all seem to be manufactured to the same high quality standards. I would make the decision based on your needs and the type of steel you'll be servicing. I don't think you can go wrong with either series.


Re: Nubatama stones

Mon Jun 17, 2013 1:13 pm

"the difference between the Ume and the Bamboo series, can anybody tell me the difference?."

"I am willing to bet Ken is going to say a few things here :) " - You bet :)

So when the original layout for the Nubatama stones was conceived, it was thought to divide the stones into two groups - a higher series, the Bamboo (Take in Japanese called Ta' Ke as two syllables ) and a regular series called the Ume (or plum) series. Bamboo was chosen rather than Take, so the stones would not be referred to as 'take' stones. :) So by and large, the Bamboo stones are a bit more expensive. Two notable exceptions are the 4k and 6k stones. The Ume 4k and 6k stones are Magnesia based stones and it was thought that they might have similar issues to the Choceras, but I suggested that they be included even at a higher cost because they have such a nice feel. I believed that users could take care of them by not leaving them soaking etc as you would a Chocera stone.

However as the full layout developed it became obvious, especially around the 1000 grit stones, that two groupings needed to be further subdivided and that sometimes the Ume stones became both excellent stones and even more popular. So at this point, the two groupings remain as somewhat arbitrary groupings simply to help identify a specific stone. However it became necessary to further subdivide by stone characteristics as the number of stones increased. Thus to help distinguish stones there is the 1000 Ume, but there are actually four 1000 Ume stones in the full series - the 'black brick' 1000 Ume, and three Speckled Ume 1000 in medium, hard and extra hard (CKTG only caries the medium at the moment, however I have the hard and extra hard in both full sized stones and for the EP). Similarly in the Bamboo series there are three 1k stones - the white (platinum), gold, and a small green stone. The small green one is there for users needing portability. The 1k White or Platinum is a premium formulation and the gold is the most affordable of the full sized bench stones, however it is quite exceptional, intermediate in hardness between the 1k medium and 1k hard stones. The 800 and 1200 while quite close in grit size, really are there to provide a very different quality, with the 1200 being an extremely soft stone to use for convex edges and single bevels or circumstances where some irregularity in the knife's surface is present - where you want a uniform finish. The 800 is somewhat soft, so it can be used as an 'aggressive' 1k.

However, from a customerr user perspective, I can tell you that I like my Nubatama Ume 1K Extra Extra Hard. If you can get that, get it for the simple reason that there is no other stone like it out there."

This stone is EXTREMELY hard. Much harder than the Shaptons. If you have used an Ozuku Asagi or Nakayama or Shinden, you know what I mean, If not think of something approaching a piece of granite that's abrasive. You would use this on the backs of chisels with a solid hagane surface. It is a bit harder to work with than the Medium hardness 1k Speckled Ume which is softer than a Shapton Pro or GS. Now if you are a Shapton fan and like a very precise stone - e.g. you are using the stone in a jig, this hardness will give you and extremely precise flat grind. Freehand users might find it gives multiple bevels on an edge rather than a more blended convex edge. For straight razor users, this precision is perfect, both for kamisori and western straight razors. Certainly if you simply like very hard stones, get this stone. Personal style trumps general recommendations.

So the Nubatama stone series was conceived as a series to meet the needs of both beginning sharpeners AND advanced sharpeners. I firmly believe that the 1k range is critical, so I provided LOTS of choices for lots of situations. There is a bias towards knife sharpeners using synthetic stones, however the series includes stones that provide solutions to users of natural stones too. And straight razor users, woodworkers and sword polishers. Yes even sword polishers. As natural stones become increasingly rare, increasing reliance on synthetic stones is a sad fact of life for this group. While not a complete substitute, Nubatama stones play quite nicely with Natural stones, enhancing rather than fighting with them in mixed series.

Another strength of Nubatama is the low grit alternatives. The lowest grit stones in the Ume series are of particular interest. I specifically wanted them to be harder formulations to wear slower than other low grit stones on the market (yes, there are other formulations available in these grits, but at this time it seemed too complex to introduce). From 120 on up they are split up between the Ume and Bamboo series.

I would like to emphasize that you can freely intermix the Ume and Bamboo series stones in use and I would encourage you to do so. Furthermore they intermix well with natural stones. And Furthermore (again), they can be used to strengthen other series of stones by supplementing their capabilities. So for instance the Choceras don't really have anything below 400. The 150 Bamboo is perfect for that series and the 24 and 60 for major repairs that would just tear up a 400. On the high end the 15k Bamboo extends the 10k and provides you with a transition from the low contrast finish of the 10k Chocera to a natural stone finish. The 15k Bamboo also does this transition quite nicely for the Shaptons too, going beyond the 15k Shapton to a just slightly softer stone with a finer high contrast finish (vs the low contrast high brightness finish of the Shaptons) and IMO a slightly finer finish than the 15k and 16k Shapton finish provides.

Now for the beginning sharpener, an excellent starter set would be the 150 Bamboo, 1k Speckled medium hardness Ume and 5k Bamboo. Mark is going to be offering this as a set. Not only is this an excellent starter set, but these are something that you will continue to use as your requirements become more sophisticated. You can transition to a natural stone polisher like a Yaginoshima Asagi, put an aoto inbetween the 1k and 5k, etc etc. This gives you a stone that sets bevels cleans up diamond plate scratches quickly on the low end. You might supplement it with a 400 if the jump from a 150 to a 1k seems large or skip it according to what you are sharpening. If you are going for ultimate level of function of mixing Nubatamas with natural stones, the 2k, 3k and 15k bamboo are the ticket, with the 5k doing duty in this group as well as for general purposes.

"Ume 1,000 = awesome" +1

In the future, I am working on an additional 2k as I see this as a gap in the current lineup. The 2k Bamboo is not something worth spending on if you don't require a very sophisticated finish and the 2k Ume is also not that inexpensive because it is large. Both are great stones, but I'm looking for something more affordable but very high quality. This is still in the development phase ... Even further out are a couple of combo stones. These may or may not come to pass as I'm not convinced this has a place, but I welcome input on this topic.


Re: Nubatama stones

Mon Jun 17, 2013 2:10 pm

Thank you very much for your reply. One of the stones I think I'm going to buy is the bamboo 400, but it's not in stock right now, so can you tell me the difference between the bamboo 400, bamboo 320 and ume 320? Thanks.

Re: Nubatama stones

Mon Jun 17, 2013 2:25 pm

The Ume 320 will be your closest match both in size and composition and a reasonable substitution. The 320 Bamboo is a different abrasive formulation, is smaller and more expensive. It is less porous. It gives a high quality finish and retains metal swarf a bit more.


Re: Nubatama stones

Mon Aug 19, 2013 11:00 am

Pulling up an old post...just the info I was looking for. Thanks for the breakdown, Ken.

Re: Nubatama stones

Mon Aug 19, 2013 7:29 pm

I can tell you the 6k bamboo and the 10k are in my line up 98% of the time and I will get the 8k soon to fill the gap. Ken has changed the sharpening world with these two groups of stones, there's one for everything that a person wants and plays well with j-Nats, Shapton's, Kings, Naniwa's SS and the Cheosera line up including the Snow White which is my bridge between the 6 and 10k that I have. What's really going to screw the pooch is when someone comes out with a 9k, that will throw a monkey wrench into everybody's line up. That was just a thought. Peace, jmbullman

Re: Nubatama stones

Tue Aug 20, 2013 10:06 am

I have an inquiry out to Ken with respect to a 4-6K stone to complement the 1K Gold. At this point, my mindset is more utilitarian than show in terms of sharpening. However, I'm sure I'll want to refine the polish/aesthetics when my freehanding gets to an adequate skill level. What do you use to fill the gap between 1-6K?

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