# Blue Aoto advice



## SaladApe (Sep 15, 2018)

My only decent stone at the moment is a big blue Aoto which I got about 13 years ago from EE - I generally use a Naniwa 1000/3000 combi at work. I'm in the process of building a proper set for home, of which the only stone I've really decided on is the Suehiro rika. Meanwhile, what's the best way to use the Aoto? It's soft and very muddy and I generally just use it to polish the bevel, but I know I'm missing out on its potential.


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## Grunt173 (Sep 15, 2018)

I notice nobody has come along yet to answer your question.I noticed it right off,early this morning when I hit the computer but didn't reply because I know that there are so many more that can give you a better answer,but I'll surely give it a shot. I only have an Aono Aoto and an Aizu-to. I have only had them a short while but my understanding is that my Aoto is somewhere between 1k-2k grit. My Aizu somewhere at 2k-4k. Also,my understanding is that without working up to much mud on your aoto it will keep you in the lower grit range of that stone and I believe yours is advertised as 2k-5k. Now if you work up a fine mud slurry it will give you a finer grit,good for refining your edge and still have some bite.The Rika 5k is a nice stone,one that I have grown to like very much,although some say it is closer to a 3k and 4k stone in grit.No matter,if I stopped at the Rika 5k, I can be happy with the final results for my working edge.
Where are you located? If you are considering other stones for your home set,that could determine the best route to take because of shipping costs.I am in the States so I have bought several Gesshin stones from JKI which I find very enjoyable to use.


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## SaladApe (Sep 15, 2018)

Thanks! That makes sense re mud. I've been experimenting and it will cut - sort of unpredictably - when 'clean' and give a nice kasumi haze when muddy. It will polish the edge more or less to a mirror finish but in terms of actual sharpening the Naniwa 3000 will more or less instantly restore an edge whereas the aoto needs a lot of effort.
I'm in the UK so I'm looking at JNS, Fine Tools etc for stones.


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## Grunt173 (Sep 15, 2018)

SaladApe said:


> Thanks! That makes sense re mud. I've been experimenting and it will cut - sort of unpredictably - when 'clean' and give a nice kasumi haze when muddy. It will polish the edge more or less to a mirror finish but in terms of actual sharpening the Naniwa 3000 will more or less instantly restore an edge whereas the aoto needs a lot of effort.
> I'm in the UK so I'm looking at JNS, Fine Tools etc for stones.


You lucky stiff. JNS has some good stuff that I would like to get myself but shipping plus this and that would kill me.


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## SaladApe (Sep 15, 2018)

I feel the same way about JKI.


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## refcast (Sep 15, 2018)

If I had to have one stone at home for J knives, it would be a medium-finishing stone, and the aoto is okay for that. This assumes I don't chip my knives, need to thin, or need to grind a fresh edge. If that's the case, then adding a 1k will cover that. Then I would get a finishing stone finer that the aoto. 


I have a kouzaki aoto that is kinda muddy. After sharpening there's leftover mud that dries to a brownish dust even though the stone is dark blue, and while sharpening the mud and stone is a dark grey-blue. I leave the mud from the last sharpening on to help start the stone for the next session.

I agree with what Grunt173 said about mud.

The stone leaves a really serrated toothy-refined edge because it's on the muddy side and it's a natural stone. The particles kind of make sawteeth within sawteeth as the particles fracture, especially since the mud kind of suspends them to do that more easily. I use it to give that kind of edge which I like more that the equivalent synthetic at either end of the grit range for the aoto. But yeah, for the cutting speed, synthetic stones are usually better. I have ones from JKI, and if I were in EU, I'd get the ones from JNS.

I would get a fine Japanese natural stone because they are splash and go, and that's convenient for me, and I like the edge more than the equivalent synthetic. The natural stone is usually harder and heavier than the comparable synthetic. I'd get muddier if I wanted a wide range of serrations, or harder if I wanted I wanted a more narrow range of finer serrations for the edge. The edge is by no means "serrated" in the naked eye visually like a saw, it's just how it feels, and what the analogy is for the edge at the micro-level.


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## Grunt173 (Sep 16, 2018)

refcast said:


> If I had to have one stone at home for J knives, it would be a medium-finishing stone, and the aoto is okay for that. This assumes I don't chip my knives, need to thin, or need to grind a fresh edge. If that's the case, then adding a 1k will cover that. Then I would get a finishing stone finer that the aoto.
> 
> 
> I have a kouzaki aoto that is kinda muddy. After sharpening there's leftover mud that dries to a brownish dust even though the stone is dark blue, and while sharpening the mud and stone is a dark grey-blue. I leave the mud from the last sharpening on to help start the stone for the next session.
> ...


So well put.


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## SaladApe (Sep 16, 2018)

Superb - thanks.

My stone is very dark greyish-blue with yellowish striations. I've been experimenting more and I've noticed that it leaves a fantastic edge on my Wat suji and not such a great one on my Kumogoro gyuto - both blue 2. Possibly because the Wat is already thin and I'm sharpening the whole bevel, and the Kumogoro is still in the process of being thinned. Probably a result of using sub-standard stones before the aoto.


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## refcast (Sep 16, 2018)

For the Kumogoro, you could try sharpening at a higher and higher angle until you can feel the stone cut a new, sharper edge onto the knife. This thins the knife until an edge forms. 

Or just start with a higher angle and work down, which produces an edge sooner. This sets a bevel and then thins it it to where you may want. 

To me, high microbevels aren't bad. Just thin behind the bevel with normal sharpening or if you feel the knife wedges or doesn't perform as well as you want. My favorite edge type is a high (about 25 degrees per side) microbevel with as thin behind the edge as possible, at least for what the steel seems to stay stable with before chipping. So I try to set as small a microbevel as possible with the fewest swipes. I also convex the whole thing by also doing a few swipes between the thinning angle and the microbevel angle, with more closer to the thinning angle. Microbevels allow me to thin more behind the edge before chipping, and I also like how they feel while cutting, which is a bit more stable and immediate.

To test sharpness, I like to use my left thumb and run it perpendicular to the edge, or see if it catches or cuts the hair on top of my head. As always, check geometry and edge formation visually and with your fingers running from spine to edge.


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## SaladApe (Sep 16, 2018)

Your explanation is excellent and I've got a much better sense of what I'm doing now. At the moment I'm flattening the whole bevel from the shinogi down to the edge, and I've still got a microbevel. The Kumogoro is a great knife but it has a fairly fat, convex bevel which tends to wedge. It's already cutting better but I really need to get a decent coarse grit stone. The aoto gives a lovely hazy mirror finish but is ruthless at exposing scratch marks so it's all a bit frustrating.


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## refcast (Sep 16, 2018)

The last thing is muddy and coarse stones can produce a dark contrast on the softer steel. When thinning, especially higher up the knife, this can cause a lot of friction going through food. You can take this off with a rust eraser or powder cleanser like Barkeeper's Friend, or refinish with sandpaper. Just sharpen the very edge again after because the process tends to get on the edge and dull it. And don't cut yourself when sanding. I cut my the tip of my index finger off once that way. 

Carrots, radishes, ginger, potatoes and such can be good ways to apply the barkeeper's friend or any other polishing-like compound.

If you sharpen to the very end of the bevel for a wide bevel knife, the very edge may start to bend during use -- this means this is the limit of that particular steel and geometry combination. Also, harder steels can chip or bend during sharpening as well. 


In diagnosing wedging you may consider whether you want to thin just behind the edge or higher up the blade if it has "shoulders". In this case, it may be where the wide bevel stops halfway up the blade face. But this will reduce food release power, as that shoulder is pushing away food. 

The more surface area on the face of the knife, and the "stickier" the surface, the more stalling the knife will have in food. This can happen after thinning due to a stone's finish on the knife. You can gauge stickiness or roughness by moving your finger across the knife surface, and compare it to other surfaces around you, with a common slick example being like a teflon pan. 

There are a lot of "types" of wedging. One type is due to the shoulders I mentioned. In this case, the knife may make the initial incision, then get stuck. 

Another is to due to thickness immediately behind the edge. This may make the initial incision require more pressure, and then after a bit of force, the knife will split the food apart like an axe head. I often use a guillotine like motion to cut with these. 

Another is due to having that rough blade face, and in this case the knife will be easier to use because it is thinner, but harder because there is more friction. Warm/hot water and subsequent cooling seems to shrink scratches and make the surface a little less sticky, so you may give that a try as well, but it seems to change the sharpening and edge taking characteristics to me juuuuust slightly. Easier to sharpen, softer feeling, more forgiving, slightly sharper, but it less immediately bites into food because its less "stiff" feeling. That is, consider the edge a spring. A stiffer spring needs to push down less before it cuts. A softer spring needs to bruise and push down until the surface gives. 

A good thing about natural stones is that the finish it leaves is pretty good in nonstick properties, and so you can go back to testing the performance of the knife without refinishing.


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## Grunt173 (Sep 16, 2018)

SaladApe,
I sure am glad you started this topic. refcast is teaching me a lot too. Thanks refcast.


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## SaladApe (Sep 17, 2018)

refcast, the coarse stone/dark contrast issue is exactly what I have going on. What would you recommend as the coarse stone in a thinning progression?


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## SaladApe (Sep 17, 2018)

Grunt173 said:


> SaladApe,
> I sure am glad you started this topic. refcast is teaching me a lot too. Thanks refcast.


Me too!


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## refcast (Sep 17, 2018)

I actually don't know a good particular stone to recommend for thinning that doesn't give dark contrast. I've used a coarse DMT and the 1000 grit diamond stone from Japanese Knife Imports, and those don't leave much contrast but the scratches are much deeper than a normal synthetic stone. Some people like to use Atoma 140. It was more convenient for me to just use Barkeeper's Friend after thinning, and to also move up to a higher grit stone to make a finer finish, and I thought that was a fair trade-off for not trying to find another coarse stone. I use the Gesshin 400 and 220. If I had to get one coarse stone I would get the 220 grit again, or similar, because I would only use a coarse stone for pretty extended thinning sessions. With such stones, I would thin to just before how thin I might want, because I have to remove the deep scratches that are left over. At least with the 220 and similar low grit stones, they should be well-cleaned so swarf doesn't build up and make the stone cut slower. Those stones are quite porous, and the clogging does make cutting more even but also much slower, so a trade-off.

Splash and go stones seem to leave more polish and less contrast, so you may look into that, as well as perhaps coarse natural stones. Both seem like they would generally cut a bit slower than soakers, but I haven't tried them yet. My coarsest natural is perhaps 800 grit at the lowest, but it cuts about half as fast as my Gesshin 1k. At the low grits, it seems synthetics cut much much faster.


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## Grunt173 (Sep 17, 2018)

My lowest grit Synthetic stones that I use for thinning because I don't want the contrast that a natural would give are the Shapton Pro 320, King 300 and the Gesshin 400. Sometimes I wish I had something in the 220 like the Pink Brick or similar. For all the thinning that I need to do I just trudge on with the stones mentioned. They work but just a little slow. A word of caution though,even the King 300 leaves some contrast.


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## SaladApe (Sep 17, 2018)

I'll probably go Pink Brick as I can get one quite easily on this side of the Atlantic.


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## Brandon Wicks (Oct 5, 2018)

SaladApe said:


> I'll probably go Pink Brick as I can get one quite easily on this side of the Atlantic.


I have the same Aoto. For thinning I use a 
DMT XXC
Pink Brick 220
Beston 500
Bester 1000
Aoto

If I'm going higher grit, depending on the knife and usage.
Naniwa SS 5000
Honyama 10000-12000 grit J-nat from EE

The combo of the Pink Brick and Beston 500 do an excellent job of removing the scratches from the DMT XXC. 

I also second the comment about thinning just shy of what you want on the coarsest stone.


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## jacko9 (Oct 5, 2018)

I have the Aono Aoto and I find it to be a very fast cutter. Maskim posted an explanation of the actions on Natural stones on his web site that I found interesting;

http://www.japanesenaturalstones.com/jns-grit-fines-and-hardnes/


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## Olsen (Oct 11, 2018)

But he also mentions that it only relates to finisher stones and not coarse/medium stones like aizu and aoto. It would be interesting to know what makes these stones different from finishers.


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## nutmeg (Oct 12, 2018)

SaladApe said:


> It's soft and very muddy and I generally just use it to polish the bevel, but I know I'm missing out on its potential.



Try to soak it an hour in fresh water before use, this gives often cleaner results with soft stones.


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