Aoto (Blue) XL 2000-3000 Grit
Japanese Synthetic Whetstone Review

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Synthetic (Blue) Aoto 2-3K grit Japanese Whetstone

Originally I didn't plan on buying a synthetic Aoto stone, because I already had 2000-3000 grit natural Aoto stone. Unfortunately, natural stones are kindda like beings with their own mind. One day my natural Aoto decided to quit on me. As in it developed small inclusions on the surface, and they are substantially harder than the rest of the stone. Really strange thing to be honest, I have never heard or seen anything like that before. Well, considering that that 2k-3K natural Aoto was the only natural Japanese waterstone I have ever had, I can't really generalize on that. To clarify, those hard inclusions didn't develop as in grew by themselves, just as I was using and flattening the stone they slowly showed up. About the same time Dave Martel started carrying in stock synthetic Japanese Aoto stones, also called Blue Aotos. One of the positive aspects was the natural Aoto stone powder in those synthetic stones. Based on my previous experience with Kitayama 8000-12000 grit Japanese waterstone, I've decided to go for it. I've had an email exchange with Dave, to pick the stone, they come in several sizes and finally decided on the XL size. That was around the end of September 2009, and before October 2009 I had it in my possession.


 - Synthetic (Blue) Aoto 2000-3000 grit waterstone is no questions asked, the largest waterstone and sharpening stone I have ever seen or handled. That thing is a monster. Exact measurements are 225mm×95mm×60mm. It's a really heavy one too. Well, you see the size, you can guess, any stone of that size will have considerable weight. As mentioned above, synthetic Aoto waterstone is made from the natural blue aoto stone powder. And one of the really cool things about that powder and natural waterstones in general is that as the mud builds up, the waterstone particles tend to break down to finer grained particles and the grit goes up from 2000-3000 range to 5000-6000. Pretty much doubling it. Natural one acted the same, before it started freaking out :(

The XL Blue Auto waterstone arrived packed in the box with the makers logo. No nagura stone with it, but at that grit it's hardly necessary. Besides I have several naguras at home already, one came with Kitayama waterstone, two more came with 5000 grit Naniwa Chosera synthetic whetstone and 10000 grit Naniwa Chosera Super Finishing waterstone. Then I bought separate, higher grit, hard nagura from Dave. I'll review that one later. Stone was pretty much perfect rectangular shape. No chipping anywhere on the edges or the surface. Considering the advise to break it in before using it, I've soaked the Aoto waterstone in water(doh!) for about 15 minutes and used DMT 8XXC diamond stone for its initial surface scrub or flattening or break in. The whole procedure lasted about 3 minutes and the synthetic Aoto waterstone was ready to go. Except I wasn't :) I had no knife to sharpen that day, so the Aoto had to sit in the sharpening equipment closet for next week or two. Before I managed to get a good workout for it. To be honest, I never have troubles finding a knife to sharpen, if not my own, then there's plenty of friends with very dull knives, but at that time I was working very intensively to get the version 1.0 of the Interactive knife steel composition chart online, hence the delay.


- The first and quite serious test for the synthetic blue Aoto was the Henckels Miyabi 7000MC Santoku knife. Made of the ZDP-189 steel (MC66 in Henckels classification), hardened to 65-67HRC on Rockwell Hardness scale, that steel is a good challenge to any sharpening device and the person shaprenning it too. I've started with lower grit, namely - 1200 grit King whetstone since Miyabi Santoku didn't need major metal removal. Then it was Synthetic blue aoto's turn. Major removal or not, now the bevel was finished with the King stone, burr was formed from both sides, and it was normal starting point for the Aoto. I.e. no shortcuts, no easy ways out. Like I said, the stone is big, and on its first use I was really surprised, in a very good way, how much more convenient and easier large stone was for sharpening. A lot of surface, provides good support for most of the edge and forget puny Miyabi Santoku with 180mm long blade, I could go through the entire edge in one sweep even with 300mm yanagiba.

Soaking time, based on Dave's recommendations, which I follow closely, about 15 minutes. Sometimes I do create mud with harder Nagura, sometimes just go sharpening. Can't really tell the difference for now. As for the cutting performance, it's about the same power as with the natural aoto, but the sheer size, i.e. sharpening surface which is about twice as large does make big difference. Overall, the work is done much faster. More metal is removed in one pass, because of the larger contact area, that is as simple as it gets ;) Another factor aiding the speed is the same large surface, knife has more support, you worry less about control, and consequently, one can move faster, but keep precise movements. Water consumption is quite good. In other words, pretty low. There is one aspect to this whetstone, I'd have to warn you about - Aotos whetstones, whether natural or synthetic, are relatively soft stones. At least in 2000-3000 grit range. Well, it's a stone, even though it is a waterstone, remember I said relatively :) So, don't pat anybody with it. Jokes aside, you do need to pay attention to the knife, angle precision and pressure you apply. When the edge is moving into the stone, i.e. cutting motion, be careful not to cut into the stone. I was well aware of that fact long time already, and still, after switching from King waterstone to blue Aoto I did manage to hit the stone with the edge and it sort of dug into the stone, just about half a millimeter, but that is enough to ruin the edge, and it is nothing good for the stone surface either. I was still careful enough not to cause a disaster neither for the edge, nor for the stone, but it was a good reminder that I am nowhere near in terms of the sharpening skills where I would like to be ;)

In the end, I was done sharpening that Miyabi santoku in less than 30 minutes, and if I wasn't testing the synthetic blue auto for the first time, perhaps it'd be even faster. Mainly, I kept on sharpening, with lighter pressure to practice on large stone, and second, I wanted to see how refined and polished the edge would end up as the aoto particles were breaking down. In the end, I've ended up with semi-mirror polished edge, which was already hair whittling sharp. That isn't a miracle in general, but doing that with 2000-3000 grit waterstone does speak very good about that particular one. Plus, I'm glad my skills are evolving. Later on, Synthetic blue aoto became permanent member of my basic sharpening setup. Obviously, it is also in complicated sharpening setup as well, which is about 7-8 waterstones and diamond benchstones, plus 304 microabrasives. Strange, when I wrote the last sentence, I thought that's a looot. Although, whenever I sharpen, I never feel it's that long of a procedure, unless it goes on for 5-6 hours. Anyway, to give you the approximate list, synthetic blue aoto very successfully handled sharpening of the: Several Chroma Porsche knives, it's a shame they're called kitchen knives though; Aritsugu Kamagata Usuba, which is Aogami II steel, around 65HRC; Aritsugu A-Type gyuto, Gokinko steel, ~60HRC. Watanabe Kuro-Uchi Nakiri and Watanabe Kuro-Uchi Sakekiri Deba, both Aogami I steel, 63-65HRC. Over a dozen Global Kitchen Knives, Chromova 18 steel, quite wear resistant too; Few mainstream Henckels and Wusthof kitchen knives - X50CrMoV15 steel. As you can see, I've gone through multitude of knives and steels, from very soft Chroma knives to super hard Japanese kitchen knives. Aoto performed remarkably and I hope it'll server well in the future.


- As you can guess, I am very positive about this stone. I like the size, cutting performance is good, water consumption is also good. Yes, I do have to be careful not to cut into the stone, but that is in away also very positive, because it helps to develop sharpening skills and keeps me focused on my technique. I love its size, makes everything much faster. You hav eot conisder two things when buying the stone, how long are you planning to keep it, and how important is the size for you. If you change the stones often, then perhaps it's not really worth to buy more expensive XL synthetic blue aoto, and you can settle with smaller one, if you really want wide stone, then go for the XL. At some point, Dave was selling those aotos cut in half (height), that was a good saving too. Not sure if those are still available, but a lot of KnifeForums members went for that. I sharpen quite a bit compared to average guy, but nothing like what pro sharpeners do. So, technically I didn't really need the stone this thick, but you never know ;) I wasn't really pressed to save 30$ between L and XL blue aotos, and I got the bigger one. In this case bigger is clearly better ;)

Last updated - 05/19/19