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Ceramic stones in finer grits - chipping

Sun Jan 20, 2013 2:40 am

I recently bought a 5000 grit Naniwa stone and managed to slice the surface twice while sharpening several knives. I've never nicked any of the courser stones in the set, so I'm wondering if the finer grit stones are more vulnerable? Was I heavy handed? I used a flattening plate to remove the nicks, but I'm also wondering how much of the surface of a ceramic stone can be removed if I am careless in the future?

I'm beginning to wonder if I should invest in a Numatama Bamboo which I think is much harder and thicker.

Richard

Re: Ceramic stones in finer grits - chipping

Sun Jan 20, 2013 4:56 am

If your gouging the surface of your stone your holding to high of an angle. Depending on the brand, most stones do get softer the higher the grit. Many will just strop on higher grit stones to avoid gouging and it helps more with burr removal. If your going to use an edge leading stroke on a high grit stone very light pressure should be the norm and really watch your angle.

Re: Ceramic stones in finer grits - chipping

Sun Jan 20, 2013 4:35 pm

Thanks Jeff,

Yeah, I think I got a little careless as I brought the knife down onto the the stone, and I started pushing before I set the blade angle.

Re: Ceramic stones in finer grits - chipping

Mon Jan 21, 2013 3:23 pm

Yeah, try push/pulling on a Naniwa 10k Superstone. Yikes..

Re: Ceramic stones in finer grits - chipping

Mon Jan 21, 2013 5:45 pm

The Naniwa 10k is suoer soft. Superstones in general are pretty soft. If you do edge leading strokes, a light touch and careful angle control is required. This won't be the last time you gouge a stone. Fine diamond films are also easy to gouge.

The trick is to develop skill using these stones and also use edge trailing strokes to almost eliminate the problem. Avoiding all soft stones is an unnecessary restriction to impose on yourself. I have several types of natural aoto that are even softer than the 10k Naniwa for instance. Great stones.

The Naniwa Chocera 5k is also a soft stone. If you want a harder 5k, the Nubatama 5k is harder. The 5k Shapton pro is VERY hard.

A word of advice. If you nick a stone, clean up the nick of sharp stone edges that may cause scratches and use the stone as is rather than lapping it down and wasting stone. It will serve as a reminder not to do it again. With natural stones, you need to learn to accommodate around surface irregularities, so dealing with nicks is a worthwhile 'skill'.

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Ken

Re: Ceramic stones in finer grits - chipping

Mon Jan 21, 2013 11:56 pm

Hey guys,

10k takes us into fetish territory. :-) I'm not there yet, but I do have an 8k Naniwa that I've never nicked. But, it leads me to ask, "At what point are you just substituting a stone for stropping?" BTW, I think we are all potentially fetishists. It's just a question of finding what turns you on.

Re: Ceramic stones in finer grits - chipping

Tue Jan 22, 2013 10:49 am

Interesting question. If my strop contains a a 30 micron particle, I'm stropping at 500 grit :) If my stone is a 30k stone (0.5 microns) well I might be stropping with something 20 times finer after that. From that perspective a 10k stone isn't even a mid grit stone :) OK, so I'm a little extreme :) And having some fun here...

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Ken

Re: Ceramic stones in finer grits - chipping

Tue Jan 22, 2013 2:31 pm

I don't feel as though I'm ever substituting a stone for stropping....but then again I'm not a huge stropping person. :)

I'm never seen a video of a Japanese knife maker/user/etc. using a piece of balsa or leather or film to strop on.

Now, that doesn't mean I'm against it....it just means I choose a different path. :)

Re: Ceramic stones in finer grits - chipping

Tue Jan 22, 2013 9:31 pm

The best way to avoid chips is to learn to master pressure. This one concept allowed me to up my game to the next level. I now visualize that grinding only takes place on my sub 1K stones, anything above 1K I am constantly adjusting pressure to allow for refinement, not grinding. It's almost like you mentally process this concept then your body mechanics learn to follow with constant practice. I can still use both edge leading and trailing strokes on all my finishing stones all day without any worry of gouging/chipping, as long as I'm modulating pressure. You'll read many of the veteran sharpeners on this forum and others discussing this topic, which is why these resources are so valuable, for those of us that are willing to really dig into it. -Josh

Re: Ceramic stones in finer grits - chipping

Wed Jan 23, 2013 10:43 am

Adam,

Just as an historical note, there was a book written by a Japanese barber about 50 years ago who used mostly Nakayama natural stones with various naguras. He followed this by ... stropping using chromium oxide on newsprint. This was oriented towards straight razor users but ...

There is a famous strop (Horse) by Kanayama from Tokyo ..

Now I haven't seen any evidence of using felt to deburr among the Japanese...

but we should learn from tradition, not be slaves to it. There's a lot of good ancient knowledge.

As Jeff mentioned earlier, bad angle control will cause you to slice the stone. And add more pressure to it and you're crusin' for a bruisin'.

There is no one perfect path.

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Ken
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