Review of Nubatama 320 Platinum

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Review of Nubatama 320 Platinum

Post by atang »

I picked up a Nubatama 320 Platinum from Ken and I’ve been able to run a few different steel types with it in full sharpening progressions.

Initial impressions
It’s a very dense stone. Heavy for its size. Slightly longer in length than a standard size stones. Takes in water quickly and lets it out almost as fast. This slows down slightly once fully saturated. I have found a 15-20 minute soak working well for me. Lapped it before I used it with diamond plate and no issues in the first session. I also attempted to lap with my 150 bamboo and it does remove some stock from the 320, but the 320 was also removing some of the 150. I guess they can flatten each other simultaneously, lol. No, I don’t recommend using them in that manner. Just a note on the cutting ability from both stones.

Very unique stone. It is very hard. Feedback is excellent since the stone is hard. Less forgiving of errors, but you immediately feel when the knife has lost its mesh with the stone surface. It is a very dense stone and the mass it carries does absorb some of the “feel” from stone to knife to hands. Also noticed that the type of knife being sharpened is a greater variable in perceived feedback. All great indicators of quality abrasive density.

Stone performance
Fast cutting stone. Not the fastest, but it’s high performance in many aspects. Most notably the lack of abrasive released from the surface. Swarf is almost black and thin in body as there is not really a “mud” type texture to the slurry. It doesn’t leave a significant amount of contrast, but I guess it doesn’t really matter if you’re taking it higher(I would assume all would follow up with a higher grit).
Here is where I think the stone excels; I was looking for a lower grit stone to do shaping work and foundation to establish shinogi line. It cuts fast and leaves a very clean line without any stray scratches or haze above the shinogi due to the absence of abrasive in the slurry. Exactly what I was looking for and it delivers! The stone is very resistant to dishing and helps maintain the precision needed for such work. Works well with all steel types. I don’t have any highly wear resistant super steels to test, but I think it can handle them as expected. Could always bump it up with some diamond emulsion too.

The scratch pattern is tight and shallow. Again a note of grit density. Easily and very quickly removes scratches from 150 Bamboo. Even from an atoma 140 it’s not too difficult.
The shallow scratches are another benefit if you’re taking the finish to higher levels; the time spent on successive stones is going to be much less. I follow the 320 with a 600 and it was relatively quick to pull these 320 scratches out.
I even tried going straight to the 1k bamboo hard and it is doable, quicker for softer stainless. All in all, the finish left from the 320 platinum itself is not much to look at, yet considering many will take a knife beyond 320, it is a very versatile finish and follow ups will be quick.

I needed a lower grit stone for specific repair work, rough finishing, and removing coarser scratches. This stone ticks all the boxes and performed these tasks well. I must also note that this stone is NOT for top repair or spine work. I have other stones for these tasks.
With the review coming to an end, I must say that this stone is not for everyone, and that there are many competitive stones in this grit for general use. The way this stone behaves may fall somewhere in between a ceramic and traditional synthetic. If you need muddy coarse stones, or the fastest 320 out there, this may not be for you. However my needs required a little more than the average 320, and at the price point of the platinum, was worth purchasing the right stone the first time. The Nubatama 320 Bamboo fills a very niche need in my coarse set and I couldn’t be happier.

Thank you to Ken and CKTG forums!
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Lincoln Nebraska

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Re: Review of Nubatama 320 Platinum

Post by Drewski »

Great review. Thanks for putting in the time.

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Re: Review of Nubatama 320 Platinum

Post by old onion »

Pretty darn good review. Thanks.

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Re: Review of Nubatama 320 Platinum

Post by Robstreperous »

Thanks for the very well written and thorough review. I remember the first time I used one of these. I forget whether it was a 320 or 600.

I ran it through what I thought was going to be my first trial pass. What ordinarily would have just been a couple of strokes, sucked in my breath and said... "You're kidding... can I possibly be done? Is that it?"

I've been a convert ever since.

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