I usually prefer not to post much as I feel that I learn more by listening to more experienced persons. However, in response to a request from a good friend, I am going to start a small series of reviews covering both stones (synthetic and natural) and knives. Keeping that in mind, this is my first review, so if I need to add anything in the future please feel free to let me know. I also do not feel it is appropriate to divulge any information in an open forum as to where I purchased my items. If you are interested, please feel free to PM me and I will be glad to give this information to you.
The second disclaimer: My stone photography sucks…taking pictures of stones is about the hardest type of photography I have tried. I think I make it worse by the fact that I do not have a macro lens. But, overall it shows what it needs to.
The Third and most important disclaimer I must make is that no two natural stones are alike, and my experiences with these stones are no indication of what you may/may not, have/have not experienced with your natural stones in the past or the future. In other words; YMMV. With that being said, I hope everyone enjoys my review.
I will start off with a comparison amongst my 5 Aoto. These include 2 red Aoto (actually a type of Akapin), 2 San-Aoto, 1 vintage Aoto, 1 ‘Fresh/newly mined’ Aoto (blue label).
All stones were soaked for approximately 30 seconds then rewet by adding necessary amounts of water during use (i.e. No stone was washed then reused). The test knife is a Moritaka AS 180mm santoku. For each test, the Moritaka was brought back to a synthetic 1k level of finish.
Picture of the Aoto Family Wet-
Newly Mined Aoto-Blue Label (Approximately 1-2k Inconsistent Finish)
The stone is approximately 60x60x200mm in size. It is very soft and has many inclusions on every face, rendering it virtually unusable. When I first purchased this stone, I started by lapping almost 3mm from the finished face in a futile attempt to get past the inclusions. After 2 hours of lapping, digging, washing, and testing, I gave up and used it with the inclusions (What you see below is similar to the results I attained when I used this stone for the first time). This stone is also very porous and will soak up as much water as it is given. A 30 second soak is not enough to keep the surface wet more than 8-10 seconds at maximum, so in reality a longer soak is necessary (but not done for this comparison). Once I was able to keep enough water on the surface to keep the blade moving, I produced a massive amount of mud. The strange part of this scenario is that once the mud started forming, it endlessly gushed from the surface no matter how lightly I stroked. The mud produced was very thick, almost hakka like in consistency, but not nearly as fine and incredibly scratchy. It felt as if I mixed in silicone carbide into the slurry. This thick mud did allow me to keep my blade up off the stone enough not to catch any of the linear inclusions while I was trying to polish the blade road, however the scratchiness from the apparent rogue particles provided a very inconsistent finish (see below). Further, during my attempt to produce a burr with this stone, more problems became apparent. Not only did I never manage to produce a consistent burr (which was strange), but during the attempt I managed to gouge out nice little chips in the edge of my blade as I hit those nasty linear inclusions. Overall, I must say this stone is a bust for knives. Since I acquired it over 1.5 years ago, I have downgraded it to a finishing stone for lawnmower blades and axes. It often follows 220 grit grinding wheels.
Stone Close Up
Picture of Moritaka with 1k finish
Vintage Aoto-(Excellent 3-4k stone with even finish, but a few shallow scratches)
Size is approximately 60x75x210mm. This is an excellent specimen from a vintage time period. I only wish I knew which mine it came from and when it was mined. Sadly, I have much less to say about this Aoto than the first, except that this stone actually works for its intended purpose. All but one of the faces has been shellacked and the finished face has a few colors to it, including a dark brown inclusion which can’t be felt. You can still see skin and irregularity on the sides and bottom from the mining process. It appears as if the miners were really trying to get all they could from the stone instead of just whacking off huge chunks to try and make a perfect rectangle. A 30 second soak is sufficient to keep this stone wet for almost a minute, which is a testament to how hard this stone actually is. There is only 1 small inclusion that can be felt at one end of the stone. It is easily avoidable or just as easily dug out (I chose to dig it out). This stone has a lot of personality, but is also very intuitive and seems to know when and how to work. It’s difficult to get mud from it, but not a chore, and the mud it produces is quite thick, but has no (or very few) rogue particles in the mix. Once you produce a nice mud, it is easy to maintain with the addition of small amounts of water and only gives off more when you call for it with heavy strokes on the blade. That being said, you must know when and how to use pressure during sharpening or you will not get the best out of this stone (an inexperienced user will produce far too many deep scratches and will not be able to refine the mud well). This stone is also incredibly fast for its finish, taking less than 8 min to produce an excellent finish and great edge. Overall, it provides a nice and even finish with very few odd scratches to ruin the look of the blade road. It is also quite easy to develop a burr, and when I wasn’t careful I developed a large burr that tended to be difficult to remove. I feel this stone is an excellent middle stone as a base for putting a nice kasumi finish on a Japanese knife and is an excellent maintenance sharpener due to its ease of burr formation and the resulting toothy yet smooth edge.
Moritaka with 1k finish
San-Aoto (Excellent 3-5K finish….but little too small for knife use)
First, a little about the history of the san-Aoto as I understand it from my discussions with others. San-Aoto are actually types of vintage Aoto that were either cut down as tailings from larger, vintage stones, or have been exhaustively used and thus become smaller over time. These are more readily available in the market than large, quality, vintage Aoto (which are almost impossible to find, and require the loss of a kidney to purchase). Interestingly, the san-sized Aoto do not appear to be in high demand although their quality, fineness, and speed should dictate otherwise. I can only assume their lack of popularity is due to their small size which is approximately 40x40x200mm.
Continuing to more direct evaluation, these stones are very similar to one another, and in fact, are difficult to differentiate by look alone. However, upon close inspection and use, they do have some individual features that set them apart. Neither stone contains inclusions, while one has a bit more skin, more irregularity in size, and is slightly coarser. The other stone produces both a finer finish and far less mud. With that being said, mud is easily produced from either using medium pressure and I am astonished at their quick ability to refine an edge and finish after just a few minutes work. It takes very little effort to bring either of these stones to their full potential, a feat not as easily realized with my other Aoto. They seem to have the perfect balance of hardness, fineness, and mud production necessary to produce a very nice kasumi finish. As far as I can tell from my rather limited experience with these 2 stones, they have very few shortcomings, and in fact their only limiting factor is size. Although they can and are used on my knives with success, they are much more suited for use as a stone in a natural progression for straight razors, which is actually how they are marketed.
A few quick notes on my sharpening experience: They produce a slightly finer finish than my vintage Aoto, but not enough to be concerned with unless you are using them as a finishing stone. Their mud contains no rogue particles to hinder blade road finish, and burr formation is a breeze happening in just under 4min for each stone. The scratch pattern from either stone is nice and dense, and the scratches are less deep than that from the vintage Aoto. Overall, these are excellent specimens for anyone who wants to try out an authentic, top quality, Aoto without having to pay a small fortune. The size of these stones really makes them perfect for straights, and although they can be used for knives I personally do not recommend it unless you are very experienced. The size makes it more difficult to produce an even finish along the blade road because you are required to sharpen in smaller sections than on a full sized stone. But, as you can see on the pictures, with a little practice, a near perfect Aoto finish is possible. One last note, the san Aoto that provided the best blade road finish also did not polish the hagane very effectively. This is easily overcome by following the san Aoto with a nice Takashima or Hakka.
Moritaka with 1k finish
Red Aoto (3-4k Finish with Dense Scratch Patterns)
Ok, these are not actually Aoto, they are a type of akapin, I believe from the (censored by me) mine. But, they are in the same basic finish range as an Aoto so I included them in this review. The size, ease of use, nice and even finish, and current ease of procurement make these stones stand out among others. To start with, they are red…well 1 of them is red and the other is more of a red/green. The one has a few really dark inclusions that almost resemble karasu like patterns. Their size is approximately: 35x75x200. When I received them, they required little lapping, which I found a nice change of pace. The lapping process was easy, and produced a large amount of mud very quickly…this caused me some concern after the experience I had with the blue label Aoto. However, my concerns quickly faded when I started using them. I have to admit, they are softer than my vintage Aoto, but harder than my san-sized Aoto. A 30 second soak is enough to get them going, but you will probably want 45s to a minute before they really perform as I feel they are intended. These two stones are night and day different from one another and from any other Aoto I currently have in my possession. One is a little scratchier than the other, while both produce mud in just the right amounts and release new mud as you would expect during sharpening. Burr formation is a little more difficult with them than with either the vintage Aoto or the san Aoto, but was still possible within about 5-6min. There are very few rogue particles to destroy the delicate finish on the blade road. They do not refine their mud as easily as I would have expected though, as I had to work for 8-12 min depending on the stone for the mud to provide the finish shown in the pictures. Overall, they are a good, full sized, entrant into the Aoto field that will give you a solid reference point to work off of. I would not use them as a final finisher, like I would the san-Aoto. But, I would most definitely use them as a middle stone before a Hakka, which is how my progression generally continues. They are also fairly excellent at maintenance sharpening where you just hit the very edge.
Moritaka with 1k finish
I hope you enjoyed my reviews, and am very happy to hear feedback of what I need to add or adjust to make my next review more pleasant or informative to read. By the way my next review will entail a review comparison of the Chosera 1k and JNS 1k. It may also contain (depending on my time constraints) a review of an Aizu that I picked up from an Acquaintance in Japan.