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i'm probably late to this party, but diamonds will cut any steel, hell, even ceramics. On the other hand, zdp189 has no super hard carbides, it's all chromium carbides, hap40/rex45 has some of those nice hard carbides, namely vanadium, tungsten, molybdenum, and cobalt, but aside from vanadium, all those carbides can be cut by alox, so things like naniwa/shapton, but it doesn't have enough vanadium to really affect that even, you can cut k390(9.75% vanadium as opposed to 3.3% on hap40) on alox. Diamonds will cut everything.

Hello thank you, yes theoretically this will work but we would recommend first insure that the wood block surface that you will be using to wrap the sandpaper in is flat. And that that you are using a wet/dry or wet type sandpaper.

The bottom of the Ceramic tile is also useful

Thank you for your comments. This is from a person who worked in the Japanese sharpening stone manufacturing industry for many years, and he told me that in Japan there are no set rules for determining the grain size of sharpening stones. The grain size is determined by the manufacturer's own sense. For example, even if the same 800 grit is used, the roughness varies slightly from company to company, so depending on the sharpener and the steel to be sharpened, it may be difficult to move from coarse to fine sharpening stones in that order because the grit depth is not consistent with what the manufacturer has stated on the product, This is a big problem for some sharpeners who use the 800 grit but are not able to produce the exact scratch.

That make sense what you write. For the preference, we recommend using a the new series Oboro Knife #200-800 is for rough sharpening, and the Hakuto2 3000S and 6000S (softer stone) is for medium polishing, we believe you’ll like the combination.

Unfortunately, the lowest sharpening stone NSK Kogyo currently produces is the Oboro Knife #200 or Hakuto1 #200.

Normally NSK Kogyo diamond stones are made with 3mm+ diamond abrasive . This is relatively thick abrasive, as most other diamond stones are 1mm or less. (Some of the ones used by Ivan may be thicker than that due to prototyping)

@@komonjapan yeah that’s my main problem with resin bomb to diamond stones so don’t trust that you’re gonna last very long I have a couple other ones and they lasted me a good long while but this one looks like it will last a long time

@@lordstick3113 Wear of sharpening stones is one of the problems that sharpeners like you are always faced with. NSK Kogyo sharpening stones are thicker, cut faster, and are harder than the Hakuto series, especially for the Oboro Knife, so they will surely solve that problem.

Venev have 3 mm of thickness but these Def look a bit bigger but like the comment said maybe due prototype.

We'll release Diamond Nagura soon on Komon's website or our partner shop in the world.

I been looking at these stones what series did you buy and how are your edges ? anything they are similar to or ?

Thank you for your comment! We just posted 2nd video which is about Ivan's sharpening with NSK Kogyo's stone. I hope you can check it soon.

Thank you I follow Ivan's amazing work for longtime .It's so good to see fresh videos from you guys often now .I'm going to buy and use all the Oboro set . Kind regards Balazs 😊

NSK Kogyo's stones may change your sharpening experience

It's depend on the sharpening what you would do, but for new line Oboro Knife, we recommend #200, 400, 800, 2000 would be the good set.

@@komonjapan And how would you rate these vs Naniwa professional stones? In speed/ feedback and longevity. And if you would gradually switch from naniwas, which ones would you replace first. (have 400 800 1000 2000 3000 and 8000). My main use are some of my japanese kitchen knives, like my fujiwara denka etc

Both Hakuto1 and Oboro Knife are harder, faster cutting speed and have excellent feed back, the Oboro knife being harder of the two. To start I would recommend Oboro Knife #400 or if you are only maintaining the edge Hakuto1 #1500. The Oboro Knife #400 is very egressive and can remove minor chips or reset bevels quickly, the Hakuto1 #1500 is a good all round stone either on its own or as a transitional stone into higher grits.

@@komonjapan thank you very much for the reply, and I assume both outperform naniwas when it comes to more excotic steels due to the diamonds. (High vanadium steels) And do they last as long as a normal whetstone or longer?

Of course! You can always contact us through Komon's website.

@@komonjapan as a point of reference for wear, how many knives can you sharpen on kyokuha series until you need to re-flatten the stone?

Thanks for your question! It is a little difficult to answer because so many variables that play into 'how often you need to flatten'. For example- what type of knife are you sharpening (single bevel vs double bevel)? Are you doing edge sharpening or thinning? What state of polishing are you in? All of these can give drastically different answers. That said, for reference, when Ivan used to use Chosera stones for rough polishing, he often found he needed to re-flatten his stones every 10-15 minutes to maintain performance. With the NSK Diamond stones, there are times when he doesn't need to flatten more than once in a two-hour session. For honbazuke (final edge sharpening) with NSK Diamond stones he feels the need to flatten even less than that. Hope this helps!

@@komonjapan mostly for general sharpening but also reprofiling.

@@Stgpx9 it's not even about flatting with abrasives like this. it's just about refreshing the surface. You could call it "unclogging" the stone. You do this as often as you'd like based on how you use it. The stone itself should never go out of flat much if used correctly and the stone itself should have a very long service life. that is my exerinced with such stones but I have never seen a very soft one.

We just shot Ivan's sharpening clips and are working on making new video now. Please wait a little while more🙏