# First impressions of a synthetic "blue aoto" stone



## psfred (Aug 13, 2014)

Bought this instead of the "green brick" from Naniwa because I was intrigued by the composition. I'll never own natural japanese stones, way too expensive, and I have a use for this grit range for kitchen knives.

I shellaced all but the working face of the stone because I've read this stone tends to crack from probably differential drying. I didn't soak it for the first test because I didn't have time tonight. I'll do so tomorrow since I'm doing a knife sharpening lesson.

I tested the stone with one of the Chicago Cutlery knives I got from eBay, an older 42S chef's knife in 440C stainless. The other knives of this type I've sharpened hold their edge well and I thought it would be a nice way to test the edge holding and the stone. I reset the bevel to about 20 degrees included on a King Deluxe 300 grit, drew a burr on a Bester 700, and then on my Bester 1200, my normal sequence. Deburred on the 1200 and started in on the aoto.

First thing I did was drive the edge into the stone, of course. I like harder stone because I have a tendency to do exactly this, and I was going too fast. Went back to the 1200 and fixed the edge and slowed down. Once I got the feel of the stone, it's a great pleasure to use. Very smooth and other than my usual habit of tilting the blade at a bad time, easy to find the bevel. Not much resistance, unlike my Naniwa 3000 or the old yellow 3000 grit no-name stone I have. The yellow one is very easy to cut divots out of, and sticks terribly. Not the aoto.

The aoto is slick. Super smooth and doesn't feel at all as if it's grinding, and it gets smoother with some mud. The stone generates mud easily, but not like my Naniwa 220 SS which gushes. This stone simply accumulates mud on the surface. Not having soaked the stone, it ran dry on me as I finished and I had to add some water, which probably reduced the polish a bit. Never chattered or dragged on the blade. Very Zen.

However, when I was done and stropped it a bit on some green chromium oxide and cleaned it off, with the loupe I see nothing but some fine scratches and a semi-polished edge. No burr, no nicks, no big scratches, just a very very clean sharp edge. The knife easily slices limp cucumbers transparently thin and will slice a nearly rotten tomato in 2mm slices (the only things I had readily available to test). 

I suspect this stone is going to be a favorite in spite of the obvious need to flatten often -- any stone that makes mud is going to wear faster than my Besters, but it was a breeze to buzz it flat with my diamond plate to start with and it's not going to get the kind of heavy use my 1200 gets, it's not for metal removal.

If you are looking for a more polished edge than a 1200 grit stone gives you or are working up through to polishing with high grit stones for very hard knives, this is a stone to consider. Probably not useful for soft stainless, but will give a very nice general use edge to kitchen knives and a good base for polishing with finer grits. 

Peter


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## CutFingers (Aug 13, 2014)

I bought an expensive real Aoto...It was pricey but it weighs nearly 5LBS...consider the actually volume of stone you can get vs the cost of synthetics. Accidents do happen. But I would try to avoid hitting the stone too hard. Chipping out a stone is no fun. Slow down and let the stone work for you instead of your hands. 

What brand of synthetic Aoto did you get? Coarser stones release bigger particles so they will always bee more muddy. Use the stone slowly and carefully to get a uniform scratch pattern, it looks beautiful and cuts better too


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## psfred (Aug 13, 2014)

Not sure of the maker, it's the one that ************** currently has. 

For sure slow and easy is the way to use this stone. I was amazed by the look of the edge under magnification, I'm fairly certain this is the best edge I've every produced. I usually manage to get some uneven bevel and rough spots in the edge, this one was perfect from the heel to nearly the tip -- missed the bevel there so the last 1/2" isn't really sharp.

The problems people have had with this type of stone (maybe the same one, maybe not, it's not really blue and doesn't stain) I believe have to do with wetting and drying causing internal stresses in a fairly weakly bonded stone. So I shellaced all but the working surface to keep water out. I'd have used fancy lacquer, but I don't have any and I do have orange shellac. Sealing it won't help with dropping the thing, but it will prevent soaking up tons of water and then surface drying over stressing the binder.

I'll be using it a lot, I think. The edge on the other Chicago Cutlery knives I've sharped up seem to hold very well, along with the Case American Heritage chef's knife my brother gave me 30 years ago and I've only sharpened once. Both American manufacture, and I suspect somewhat harder than the usual German steel knives. I've ground them all to around 20 to 25 degrees included angle just to see how they work, and they hold up pretty well. They respond well to steeling once the edge gets some use, but they are not nearly as soft as a standard cheap chef's knife. Since they are harder, it's worth the effort to get a really nice sharp edge.

Peter


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## CutFingers (Aug 14, 2014)

The older Chicago knives that were sold many years ago at Maceys stores might very well be 56-58 rockwell, so they might be okay for a little work.


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## psfred (Aug 14, 2014)

Update on the stone: My buddy brought over his two chef's knive (and his girlfriend) and I sharpened them up. One is a Wolfgang Puck, I assume an example of typical German steel since it sharpened up very quickly in spite of re-setting the bevel. Polished nicely, edge looked very similar to my Chicago Cutlery chefs knife, but it never got quite a sharp. Second knife is a $12 no name from the local resaraunt supply store, harder than the Wolfgang Puck and was slightly sharper when I got done. Never did get the tip sharp, so he will bring it back sometime and I'll work on that. 

The aoto worked just as well on the softer steels as it did on the hard ones, but the edge wasn't as good. I think both knives need some more work, but at least one of them had been "sharpened" on a pull through carbide washer type sharpener and was in pretty bad shape in terms of edge, probably will require another sharpening soon.

The finish on both knives was semi-polish, bright but not mirror so to speak. Both knives would easily cut an over-ripe tomato I rescued from the garbage and were very much sharper than they were when I got them. The new bevel helped quite a bit too, I think.

I'm definitely keeping this stone in use, it does a great job with very little effort. I soaked it for half an hour this time, and it did not need extra water applied, stayed wet the whole time I was using it on each knife. Only a couple minutes for each one. The feel is better too, didn't have any trouble digging the edge into the stone this time and the edge looked really nice at 20x.

Peter


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## gic (Aug 15, 2014)

Where did you get it if I may ask, I have a green brick and it might be fun to compare the two...


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## psfred (Aug 15, 2014)

CKTG -- Chef's Knives To Go. It's on sale at the moment.

Peter


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## dmccurtis (Aug 16, 2014)

I've had a few of these, and although I don't use it much these days, it's consistently been one of my favourite stones. It definitely benefits from a long soak, but because it is very susceptible to cracking with drying cycles, I can only recommend soaking it permanently. Otherwise, it's not a matter of if it will crack, but when.


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