Nubatama Stone Review – with a Damacus Yanagi

Nubatama finish

Nubatama finish

Nubatama stones are the newest playthings I’ve recently received from the US distributor, Ken Schwartz of Precise Sharpening. The main idea for me was to work with him to find a series of stones that we can add to the Edge Pro custom stone lineup, but that is another story for later 🙂 I don’t anticipate carrying the whole line of these stones (I got 28 stones in 2 series in all to try out!) or know for sure if they will all make it to the US market. If they do make it you can be sure to find them at ChefKnivesToGo.com in Ken’s Corner.

As I stated, there are 28 stones within 2 series loosely grouped more or less by price into a “higher” Bamboo (竹) series and a “lower” Plum (梅) series.  There is absolutely no indication of a higher and lower quality reflected by the prices, though. The right stone for the job is clearly more dependent on the steel and style of the knife, not the series, which I quickly found out.

There are several overlapping grits, but they all have different properties, and it can drive a man mad trying to keep track!

Box-O-Nubatamas

Box-O-Nubatamas

Nubatamas  - Left Bamboo series, Right Plum series

Nubatamas - Left Bamboo series, Right Plum series

As luck would have it, one of the sushi shops I service called and the chef wanted me to fix up his Japanese Damascus yanagi. They usually have standard clad steel, so this one was more special than the usual no-name sushi knife most of the other chefs have.

Unfortunately, I didn’t get a before picture because I was just playing around with the stones to get a feel for them and didn’t realize it would lead to making a post about it so soon. As everyone knows, I am very much a Shapton man. I was going through every stone with a couple of different knives to get acclimated to they overall sense of how these stones would work, and ultimately compare to Shaptons.

Back to the knife – I started off with the 80 grit belt sander and then cleaned things up a little with the 240 belt. From here I played with the Plum and the Bamboo 180 grits. For this specific knife, I found the 180 Plum to be better suited for removing the belt scratches from the clad steel, although there wasn’t much for the stone to do here. I found that a slight trickle of water helped keep the stone working fast and refreshing the abrasive. There was no real slurry/paste forming. While the stone did release it’s abrasive, dishing was rather minimal. There is a solid feel, with a little cushion, similar to a Chosera, but with the aggression of a 180 grit.

180 Plum Nubatama

180 Plum Nubatama

Next up was the Plum 320. The #320 Plum can be used without running water, and in fact, works better with just a light coating of water to keep everything wet. A little paste did form, and since I had done my initial shaping on the belts and 180 grit Plum, I was now set on cleaning up the scratches. Overall, this stone left an even 320 grit scratch pattern with a little bit of “graying” on the bevel that is indicative of a polish beginning to form.

#320 Plum Nubatama

#320 Plum Nubatama

Then I moved to the 400 Bamboo. Here’s where things got very interesting. On other stone series, such as  the Choseras, they begin at 400 grit. Well on the 400 Bamboo Nubatama, you must have your initial shaping finished already. This stone does not do any “work” as far as shaping is concerned – and believe me, I tried! You are officially polishing at this point.

A wonderful thing about the 400 Bamboo Nubatama is that it seems to know just how much abrasive to release to form a paste, while the stone itself is still quite solid underneath. I occasionally added a drop of water to keep the paste moving around. (I ended up coming back and spending a considerable amount of time on this stone in the end.) The end result was more graying of the bevel, but with still evident scratches, although they were not as deep (technique plays a role here, too. I purposely used the paste and did not try to use the stone.)

#400 Bamboo Nubatama

#400 Bamboo Nubatama

Next up was the #800 Bamboo Nubatama. Once again, while other stones are just beginning the sharpening process at this level, the Nubatama Bamboo 800 is polishing. And like the 400 Bamboo, the 800 seems to know just how much abrasive to release to form a paste. By the end of this stone, I had a clear, clean view of the Damascus pattern, and could see any imperfections and scratches I had missed on earlier grits. An interesting not here is that when wet, the contrast of the bevel was easily seen, but when the bevel was dry, there was more of a grainy gray finish and less contrast.

#800 Bamboo Nubatama

#800 Bamboo Nubatama

Then onto the #1200 Bamboo Nubatama. Once again, things got interesting. First of all, this stone has a serial number. That raised an eyebrow….. and on top of that, it looks like a big brick of dark chocolate. 🙂

This stone is much softer and a lot muddier – there is no grit release as much as there is mud release. Think of an Aoto, in fact I am calling it that. (sorry Ken) The end result was a smoother finish on the bevel, which enhanced the dry contrast of the Damascus pattern.

#1200 Bamboo Nubatama

#1200 Bamboo Nubatama

The finish off the 1200 was probably “enough”, but hey, I got stones that go up to 10K! So the next stone is one of the most expensive stones in the bunch – the 2K Bamboo.

I must admit my Japanese Natural stone finish experience /aesthetic sharpening is zero so I don’t know what I was supposed to see on this stone, or if it was even meant for single bevels…but the stone was rather soft and chalky compared to the stones in both series up to this point.  Time will tell on this one. Obviously, there needs to be some more exploration with this stone to unlock its potential. Either way, it seemed to make the bevel smoother than the 1200, and seems to give more overall grayness to the entire bevel – both the soft and hard steels.

2K Bamboo Nubatama

2K Bamboo Nubatama

Lastly, I used the 4K Bamboo Nubatama. Once again, something interesting happened. I usually sharpen the hollow ground side of a single bevel knife first, since the stone is at it flattest, and then do the bevel side. Well, I started with the hollow ground side, and it was terrible – nothing was happening and I was thinking this was not a stone for yanagis. So I flipped the knife over to be thorough, and suddenly, the softer damascus steel mixed with the stone and the stone instantly came alive!

That was cool.

4K Bamboo Nubatama

4K Bamboo Nubatama

That’s where I stopped because of limitations to my time and the grit of the sushi shop 🙂

Thoughts and Conclusions

Everyone knows that Shapton sharpening stones are the standard by which I compare all other stones to, but the Nubatamas I tried for this review are the first stones to come around in a while that don’t try to necessarily compete in the same way (other stones in the pile do, though). There’s still a lot of work to do with learning about these stones, but the stones here are clearly more geared toward polishing and aesthetic sharpening, meaning you do your “work” at the lowest levels, and then work toward creating a beautiful finish.

These may even be a very real synthetic solution to using Japanese Natural stones, and are unlike other synthetics that try to produce aesthetic finishes that I have tried.

Once again, the money shot!

Thanks!

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