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Thread: Polished vs. toothy edges

  1. #21
    Senior Member zitangy's Avatar
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    Quote Originally Posted by ThEoRy View Post
    With natural stones grit range varies and changes when it further refines in the mud. This causes teeth of many different sizes which abrade at different rates causing the edge to last longer.
    Hi..
    a)I am just wondering as to whether the synthetic material from stones do also eventually break down due to attrition . Are they more resistant?

    b) It is also fr this reason that I use say a 3,000 grit stone to clean or create mud on say a 5,000 grit stone. Grit contamination does replicate the desired mixture.ON this subject, the texture of the mud becomes relevant.... too watery not much slurry around. Too dry, it cant do its job. A right amount of water ( droplets, via a spray) will have the right mix and texture.

    Look forward to the above said confirmation.

    D

  2. #22
    Quote Originally Posted by zitangy View Post
    Hi.. a)I am just wondering as to whether the synthetic material from stones do also eventually break down due to attrition . Are they more resistant?
    More resistant? Yes. Break down? Apparently no.

    The source may be a nat-stone seller, but I'm a believer and I think this was also written by another member here. Easy to find info: http://www.japanesenaturalstones.com...nes-s/1835.htm

    Editted quote:

    Japanese Natural stones do not have grit like we see in synthetic ... they have flakes. These flakes will release at different rates and patterns depending on how hard or compact the stone ... these flakes will continue to break down ... if you take synthetic stones, the particles are cubed or rounded with extremely sharp edges ... These particles will deeply gouge ... leaving deep and difficult to remove scratches. Synthetic stones are also produced by grit being super-compressed into a hard resin or ceramic binder, the particles break off in huge, non-friable, chunks and stay suspended in the slurry as you sharpen. This results in very fast metal removal, but also contributes to the deep gouging ...

  3. #23
    ... A follow-up point to the above is that I think synthetic stone sharpeners will wear down their knives a lot faster than nat-stoners. I wonder about this when I read posts for example on BST where a knife might have been '55mm at the heal, but now 52'. I usually imagine there's been too much sharpening, or too much harsh synthetic sharpening.

  4. #24
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    An interesting observation that gets back to my original point -- there seems to be near-unanimity here that toothy edges last longer than polished ones. But some searching around the internets shows that there are plenty of people on other forums who say the opposite.

  5. #25
    Here's a quote from Alex at The Japan Blade which amplifies Maxim's comment about how natural stones work. This is the bible for me.
    ------------
    Natural sharpening stones, the type found near Kyoto but also in other parts of Japan, are complex in their material make up and contain tens if not
    hundreds of different elements and compounds. Some of the minerals and fossilized organic material act as cutting and polishing agents while
    some make up the binder portion of the stone that holds everything together. The harder minerals like chert, a form of flint, do most of the cutting
    while clays mostly make up the binder. Users of Japanese stones notice the contrast between the hard steel and the soft iron after sharpening, in
    Japan this is called Kasumi. Kasumi is a word that describes the fuzzy or hazy look objects take on when viewed over hot summer ground. The
    kasumi look is desirable to most Japanese tool users but few understand how this effect is achieved.

    Taking into account the hardness of these blades, in the Rockwell 60-65 range, only a fraction of the available abrasive grit mix in these stones will
    actually polish the hard steel cutting edge, the clay certainly will not. But conversely because the iron backing on laminated blades is so soft almost
    every thing in the grit mixture will affect the polish of this softer iron material, even the softer flakier grit particles.

    During the sharpening process the soft iron has been honed and reduced in mass by the effects of all of the grinding compounds working in
    unison. The chert which cuts the soft iron like butter and the clays, salts, radiolarians and even some silica that is a know element of some of the
    older wrought irons will help to sharpen or reduce the jigane soft iron as it is coaxed out of the iron base. The kasumi effect is basically the result of
    all of these lesser abrasives working together to sort of massage the surface of the iron, none of the abrasives acting on their own to over power
    the other, a little bit like Judo, which translates as "the soft way". The iron is changed and reduced and sharpened, but in a soft way.

    The hard tool steel takes on a polished mirror look, some suggest it has the look of chrome. This microscopic scratch pattern in the hard steel that
    makes it look polished has been cut by only the hardest of the hard abrasive particles and it looks regular and finished. The soft iron on the other
    hand looks dull and complicated. This is the contrast in the polish that is achieved with the natural stones. Synthetic stones give an over all highly
    polished bevel while the natural stones allow the soft iron to look soft.

  6. #26
    Quote Originally Posted by ThEoRy View Post
    Devin makes an interesting point about the teeth. Think of it this way, under a microscope the teeth would look like a saw blade. The longer the teeth are the longer it takes to abrade them down to dull. If the teeth are very fine or refined/polished they are smaller so there is less material to wear away before reaching the dull state, so it happens faster.
    I agree. However, if you imagine two toothy edges, one coarser and one finer, and if the teeth of both have been worn away the finer edge will still remain the sharper because it's still going to be thinner, no?

  7. #27

    Zwiefel's Avatar
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    Excellent write up, thanks!
    Remember: You're a unique individual...just like everybody else.

  8. #28
    To be honest i have never seen a huge difference in toothy VS polished in edge holding, however i seen more bight in toothy edge like on cutting tomatoes.

    For slicing i really dont want to use toothy edge, if you slice something like fish or fine vegs you want that shine to it that you can only make with polished edge

    The hard tool steel takes on a polished mirror look, some suggest it has the look of chrome. This microscopic scratch pattern in the hard steel that
    makes it look polished has been cut by only the hardest of the hard abrasive particles and it looks regular and finished. The soft iron on the other
    hand looks dull and complicated. This is the contrast in the polish that is achieved with the natural stones. Synthetic stones give an over all highly
    polished bevel while the natural stones allow the soft iron to look soft.
    That also may be Not true, because i can make very good Kasumi finish on Synthetic stones And also very good mirror on Jnats '
    Mud control is the most important in Kasumi finish

  9. #29
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    Never tried this, but what if you sharpen to a very polished edge and then put a micro-bevel on with a coarse stone? Would that have any kind of benefit or make a difference?

  10. #30

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