Thu Aug 23, 2012 1:45 pm
I have a situation that when I strop my knives on the Naniwa 8000 super stone, most of the times the blades on the knives become over polished and have no bites at all.
So, I would like to know will a natural polishing stone like the Ozuku Asagi (Koppa) fix the problem i.e. still gives the knives bites but also have a well polished edges. And will the Ozuku Asagi (Koppa) a good polishing stone to my current 2000, 4000, 6000 and 8000 grit stones? I am thinking not to use the 8000 grit stone and instead use the natural stone for polishing purpose.
Also, I am looking for a 1000 grit natural stone, do you have any other stone besides the Amakusa Natural Stone that is in that grit range and will not cost too much.
Thanks a lot and have a nice day.
Thu Aug 23, 2012 1:46 pm
Give me a brief list of how you sharpen a knife. I'll see if I can help you get better results with what you have.
Thu Aug 23, 2012 1:46 pm
Thanks for your reply.
Here is what I normally do, I start with the 2000, then the 4000 and the 6000 and sometimes the 8000. I start the 2000 until I get blur on either sides of the blade then the same with the 4000, for the 6000 I use light force on the blade and for the 8000 I just strop the blade for about 20 times on each side.
Hope this will give you some idea of how I sharpen a knife.
Thanks a lot, Mark.
Thu Aug 23, 2012 1:53 pm
Ok, there are ways to fine tune your edge. If you're looking for a toothy edge and don't like a polished edge you need to create teeth and then preserve them through your sharpening process. What you're doing by starting your progression with a 2K stone and then moving up in a tight progression is you're sharpening more for a polished edge.
So try this. Get yourself a 400-600 grit stone and grind an edge with that stone. Then do a light follow up with the 2K and then use edge trailing strokes with the rest of you stones. The idea here is to get some teeth and then polish them, not remove them. See if that works to give your edge more bite.
Also, be mindful when you strop on the stones with consistant angles. I notice I'm sloppy when I switch from sectioning to stropping which usually has no consiquence on leather but you can round off your edges a little when stropping on stones.
I hope some others will jump in and give you a few more tips. Please come back and tell me if this helps or if we should try something different.
Thu Aug 23, 2012 2:22 pm
Hmmm. I have a few ideas!
A Rika 5K gives a nice, sticky sharp edge on many steels and has a nice bite left to it.
I usually go Bester 500, Bester 1200, Synthetic Blue Aoto (~2K) (I use this to refine the edge, reduce the burr and to make sure my edge bevels are meeting before going to the higher grit stones; I don't really look for much grinding from this stone), Rika 5K, Shobu San (8K J Nat) and the Ozuka Asagi Koppa. After the Shobu San and the Ozuka Asagi (or Rika 5K if that is my last step), I take a piece of Micarta handle material (sanded down with 100 grit sandpaper and sprayed a 1 micron diamond slurry on and let dry) and strop on that. Kinda like stropping on a 16K or 30K stone, whichever 1 Micron is! This gives a very nice edge that still has teeth. The stropping on Micarta usually gets rid of any burr left and puts a tiny micro bevel on the edge. I can hold a paper towel in the air and make clean slices down the paper towel or sideways with this edge.
Or you can leave the edge coarser and just touch up the edge with the finer stones, IE a 400 or 500 grit stone, then a 2-3K stone, leaving the teeth from the coarser stone like Mark suggested. I prefer the Rika 5K or using J Nat finishing stones. The Shobu is around 8K or so, Ozuka Asagi is around 15-20K, the Takashima is up there, but softer so it may leave more bite.
I think people get obsessed with going to the highest polish they can get on everything. I prefer a bitey edge to most of my knives. My Tanaka blue #2 kurouchi Nakiri took an incredibly aggressive edge going from the Rika 5K to the Ozuka Asagi (before I had the Shobu) that was incredibly sharp. It had that sticky sharp smooth feeling, but had a bite to it that was scary. I would say get a Rika 5K and a J Nat finisher and use that instead of the 6K and 8K stones.
Marks 5 piece set with the Bester 500, 1200 and Rika 5K with deburring block and loupe is a great set. Add in an Ozuka Asagi, SHobu San, Takashima, etc as your finisher, but usually the Rika 5K is a great ending stone!
Or you can polish all the way up, then drop back to a 2K or 4K to put some teeth back on.
Thu Aug 23, 2012 5:43 pm
8,000 grit is often too high to take kitchen knives. Gotta have a very good heat treat and better geometry for a knife to really work with an edge 8k or higher.
Skip the 6k. Just go from the 4k to edge-trailing strokes on the 8k. By skipping the grits, and not putting in a ton of time on the 8k stone, you won't remove the entire finish off the 4k stone.
Though it is a massive rabbit-hole, Natural stones do leave a very grabby edge, even at high polish(esp on carbon steels...stainless not quite so much).
Finding a great 1k natural will be tough. They are hard to find, wear fast, and don't provide any benefit, since a 1k finish is almost always entirely removed. Most JNat users, even the hard core ones, have a 1k synthetic around. I know of one guy who doesn't, and he's still searching for a rough stone he really likes.
Thu Aug 23, 2012 7:04 pm
j-nats immediately comes to mind when I see this type of questions. there are not scientific prove to show why J-nats are toothier. but it is clear that they are mixed-grate stones. I don't have j-nats, but this is what I do, I carry some of the mud from my ume 4000 over to the 8000.
Fri Aug 24, 2012 8:41 am
Thank you guys for all your help. It definitely help me in my sharpening for sure.
I did order a couple of J-nat from Mark just to try it on my carbon knives.
Thanks again to all of you.
Wed Aug 29, 2012 11:42 pm
Come back and let us know how it works out.
Fri Aug 31, 2012 8:14 am
Steed what you are looking for is a middle grit natural stone or nakado. You can also consider a good Aoto. Some of the Nakado to consider are the Binsui or Igarashi - both finer than the Amakusa and quite hard. The Binsui is the harder of the two. Depending on your tastes you may find the Ozuku Asagi too hard for your tastes and finishing with a slightly softer stone like the Yaginoshima Asagi a better choice. Aoto are available in various degrees of hardness (more detail on request
). Try to get a pretty precise edge to maximize the benefit of the Ozuku Asagi.
Aoto are particularly nice in that they 'span a wide grit range, so you can start with an edge requiring a 1-2k stone and let the mud refine as you use it and wind up with a much finer edge - optionally following it with a polishing stone (awasedo).
The 1200 2k, 3k 5k and 15k Nubatama bamboo synthetic stones are probably the finest stones available in terms of working with natural stones - IMO
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