ZDP-189 - choosing the right waterstone

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ZDP-189 - choosing the right waterstone

Postby Cliff Stamp » Sun Sep 07, 2014 7:39 am

ZDP-189 usually gets decent comments from most people who use it with Spyderco knives, however there is one common complaint in that it can be difficult to sharpen and in particular can even chip on the Sharpmaker. These difficulties are caused by the same properties which also tend to make it praised for edge retention on coarse media :

-higher than average hardness
-higher than average carbide volume

An obvious solution to sharpening ZDP-189 and similar high carbide steels is to retreat to a more coarse stone and use the Sharpmaker to micro-bevel after grinding a large relief bevel on a new blade. But while a lot of stones are decent for a lot of knives, some stones will not work well on steels like ZDP-189, yes they will grind the steel but the edge will not form clean.

Here is an edge off of a Bester 700 which is a very decent semi-coarse waterstone :

Image

Note that the edge doesn't form clean by that I mean it fractures above the size of the scratch pattern. As the steel gets lower carbide and tougher this stops happening but with the brittle high carbide steels it can be a real problem as it causes more steel to be wasted than necessary in sharpening and you have to do more work to grind off that chipped edge. Now an obvious solution is to finish with a finer stone, here is the same knife with the finish from a Naniwa Aotoshi 2000 :

Image

While the Naniwa Aotoshi 2000 does very well on high carbide steels and won't fracture them even up to steels like Maxamet, and it grinds ZDP-189 well it is a 2000 grit stone and thus the cutting speed is much lower than the mid-coarse stones like the Bester 700. To be specific here is a cutting trial comparing the two in repeated sharpening of a basic stainless steel knife :


Bester 700 : 120 - 100 pps

Naniwa Aotoshi 2000 : 550 - 700

Now while you could use the Aotoshi it is going to take you 4-5 times as long. Ideally you would want a stone which cuts as fast as the Bester but finishes as fine as the Aotoshi - but that is impossible right? Not really and enter the Naniwa Superstone 400.

The Naniwa Superstone 400 looks like this when it is flushed :

Image


which is very similar to the Bester 700 :

Image

Close in terms of grit size and the openness of the coat with the Bester being a little more open. If you polish a blade to mirror and then do a little bit of grinding (50 passes) with each stone then they also produce very similar scratch patterns :

Image

+

Image

These are so close that it is hard to say which is which (the second is the Bester) but the Bester tends to be a little more coarse with occasional deeper scratches.

At this point you might be saying - well if they look the same and cut the same then what is the point, what are you talking about using one over the other with ZDP-189 and other high carbide steels?

This is the critical part, you normally don't just do 50 passes with a coarse stone and then stop. If you keep using the Naniwa Superstone 400 builds up a thick mud and that completely changes how it cuts/finishes. The surface of the stone then looks like this :

Image

and it produces this as a finish :

Image

The coarse unidirectional scratches are gone and it looks more like a shot peened finish. However if you use the Bester 700 it doesn't ever do that, it always produces the same directional scratch pattern because it never makes a mud :

Image

Why does this happen, this is the interesting part.

While both will build up a slurry, the Naniwa forms something similar to a colloid which is like a suspension but the particles do not sediment (or do so over a very long time).

If you stir up the slurry on the Bester then it mixes into a suspension, however as soon as you stop the particles sediment (settle) and you can clearly see the water and the abrasive (which is much larger than on the Naniwa) separately.

However the Naniwa slurry does not, it just becomes a paste/mud and you can dilute it and it doesn't sediment, you can not see water and the abrasive separately just a mud.

These act very differently when honing.

In the Naniwa Superstone :

-the slurry is finer, more dense and more of a paste and can itself acts as a polishing agent (in random directions)
-the slurry buffers the steel from the coarse abrasive (as the knife rides on the mud)
-the stone gets a much finer surface as the abrasive breaks down / fills in

Now you can make the Bester 700 act like the Naniwa Superstone if you just put a thick mud on it (from the Naniwa or a slurry stone) but because the Bester 700 will not replace it naturally the harsh scratches will come in as the mud dilutes.

--

What is the point of all of this? Similar to how you have to choose a steel to suit an application you have to choose a stone to suit a steel. If you pick the abrasive which is designed to cut the steel well (speed and finish) then problems with sharpening will disappear. However if you don't then you can create problems. Thus when people ask questions like "Does ZDP-189 have problems in chipping in sharpening?" the answer is basically only if you use non-suitable abrasives.

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Re: ZDP-189 - choosing the right waterstone

Postby Laethageal » Sun Sep 07, 2014 8:03 am

Nicely detailed and illustrated post Cliff. Have you ever tried diamond lapping film on glass to sharpen ZDP?

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Re: ZDP-189 - choosing the right waterstone

Postby Cliff Stamp » Sun Sep 07, 2014 8:16 am

Laethageal wrote:Have you ever tried diamond lapping film on glass to sharpen ZDP?
I tried lapping films a long time ago, the problem with them was that any inconsistency in application and you were limited to edge trailing as otherwise you would cut the film off. I have become interested in them again after talking to a few people and am curious if I can actually apply them with enough uniformity to do edge into honing without having to buy the abrasive sheets which can cost $100-$200 per sheet.

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Re: ZDP-189 - choosing the right waterstone

Postby Bugout Bill » Sun Sep 07, 2014 12:29 pm

Interesting commentary.

Now Spyderco needs to get into the waterstone business.
" Two guns, flashlight, two 12-gauge cartridges, and a knife because—just because—every little boy should have a knife.." -- Louis Awerbuck on his EDC

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Re: ZDP-189 - choosing the right waterstone

Postby Cliff Stamp » Sun Sep 07, 2014 12:57 pm

I think it would be interesting, imagine :

-a dual grit/density (hard aluminum oxide, soft silicon carbide) stone

As the existing benchstones are very nice for setting the apex, the waterstones would only be needed for shaping so a 100 and 500 grit stone would pretty much cover then entire range as you could move from that to micro-beveling on the existing medium ceramic easily.

The dual grit/density would allow the stone to be flexible over the wide range of steels that Spyderco uses from the ones that are very easy to grind (use the hard aluminum oxide side) like AUS-6, 420, O1 to the very hard to grind ones (use the soft silicon carbide side) like M4, S110V, etc. .

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Re: ZDP-189 - choosing the right waterstone

Postby Bugout Bill » Sun Sep 07, 2014 1:07 pm

Neat idea. Would it be possible to make an extra coarse sintered ceramic?
" Two guns, flashlight, two 12-gauge cartridges, and a knife because—just because—every little boy should have a knife.." -- Louis Awerbuck on his EDC

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Re: ZDP-189 - choosing the right waterstone

Postby Cliff Stamp » Sun Sep 07, 2014 5:22 pm

Bugout Bill wrote:Neat idea. Would it be possible to make an extra coarse sintered ceramic?
Yes and no, because sintering is a very wide term, at a basic level it means to use heat/pressure to fuse materials together. The Spyderco hones generate a very close abrasive, the fine and uf are the same abrasive, the uf just has a polish. The problem with a coarse abrasive is that it is more likely the abrasive will crack off and in any case the rate of wear will be higher. If you wear down the surface of the coarse stone and it doesn't release any fresh abrasive then what - you have to basically recut the stone with an even more coarse abrasive which can cut it to get back to a fresh surface.

I have a sigma power 120 which is an xxc silicon carbide stone which is described as being very similar to that, it is very hard and does not tend to wear or release abrasive, aside from the silicon carbide breaking down, but it has a very open structure which reduces glazing (a huge problem with the Spyderco ceramics). What you have to do with that is recut the surface periodically, not flatten it but just recut it and it comes with 36 grit silicon carbide to do that. 36 grit is so large you can see the particles by eye, they are like fine sand.

This is a stone designed for very hard to cut steels, from the sound of it I think it could do with a little more friability in the binder, but, and this is critical, stones are a very delicate balance just like alloy in steels. If you go too high on the binder friability the abrasive will shed under low to moderate pressure lie they do on the TASK and you can literally grind the stone down in a day if you lean into it heavily. I have not used enough of that batch of stones out there yet to have a feel for binders/abrasives yet in detail, but I think it can be done as I noted in general in the above to yield an extremely useful coarse and mid-coarse stone.

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Re: ZDP-189 - choosing the right waterstone

Postby dmiddleton » Mon Sep 08, 2014 9:35 am

so, naniwa stones do well for high carbide steels? i may have to pick one up at some point. i generally have a pretty easy time with my shapton 2k glass as long as the edge damage is fairly insignificant. the 500 does pretty fair as well and i can get a nice shaving edge in a minute or so off of it. i'm always on the lookout for a stone that will shave some time off of sharpening. those sigma power stones sound intriguing as well, my question is if it doesn't release abrasives very quickly, how does it work so well on high carbide steels? i have been having a much easier time grinding my ednura 4 in zdp189 since jeremy reground it, it is immediately noticeable, the difference between it being zero ground versus how long it took to sharpen it with such a wide bevel as it was in its sabre ground form.

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Re: ZDP-189 - choosing the right waterstone

Postby Cliff Stamp » Mon Sep 08, 2014 9:46 am

dmiddleton wrote:so, naniwa stones do well for high carbide steels?
They produce a fine finish, do not glaze however (assuming they all behave like the 400 I have) they cut much slower than the grit rating due to the formation of a thick mud and it also makes them not trivial to set the apex. I am not saying it is impossible to actually use them to finish the apex, but you have to know how to deal with the mud. For example I show (in very poor resolution) the kind of edge which you can get off of the Naniwa 400 here :

http://www.youtube.com/watch?v=yoLV30_ZfQg" target="_blank

Note that the first cut is an attempt at a push cut which is fairly close and just 5-10 degrees off a true push cut at a decent distance from the point of hold. It is trivial to slice the newsprint of course. The process for getting this sharpness has to take into account it is a soft/muddy stone so it is much more involved than if it was a hard/low-slurry stone

Now of course you could just very aggressivly rinse the stone under water and keep it free of mud but if you are going to do that I don't see why you would use the Superstone as they are designed to mud. If you don't want the mud then you would be better served by a different stone like the Bester line.
i'm always on the lookout for a stone that will shave some time off of sharpening. those sigma power stones sound intriguing as well, my question is if it doesn't release abrasives very quickly, how does it work so well on high carbide steels?
The Sigma Power 120? It doesn't release abrasive at all aside from what cracks off (coming from Stu, I have not used mine yet). I have used stones like this before, they have a very open coat structure and very coarse abrasive which just wears/glazes as you use it. They start off cutting very fast/coarse and slowly get fine as the abrasive wears and the spaces in the stone fill in. In order to get the stone cutting fast again you have to recut the surface with an even more coarse abrasive, it comes with 36 grit silicon carbide to do that.

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Re: ZDP-189 - choosing the right waterstone

Postby dmiddleton » Mon Sep 08, 2014 10:00 am

ah...i read that part but, didn't absorb it apparently about recutting the stone. my king 6k seems to mud some but, it seems to clog and glaze over quickly but, it's a breeze to clean it and flatten it as it seems pretty soft and it does polish steel very well. have you tried you king extra coarse yet? on a side note, my interest in possibly making/cutting my own stones has been nipping at me and i came across a flat rock my daughter had given me and i decided to flatten it with a brick, my sidewalk, and finally on a coarse stone and found it to produce quite a nice mud and it seemingly provides a finish like that of a 1k to 1200 grit and it produces a shaving edge. i am a bit proud of it. oh... and i meant to ask, the naniwa, is it on a plastic base or wood?

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Re: ZDP-189 - choosing the right waterstone

Postby Cliff Stamp » Mon Sep 08, 2014 10:24 am

dmiddleton wrote:have you tried you king extra coarse yet?
Not yet, that is really coarse as in the double digits, it looks like a masonry stone used to edge tile. I think I know enough about the Naniwa Superstone 400 to use another one now, I pick them at random just to make it interesting.
the naniwa, is it on a plastic base or wood?
I have an old one, plastic base, the new ones don't have a base as people complained the bases make them awkward as many people have those very nice adjustable holders/sink bridges. Lots of places have decent natural stones, the main reasons some places get a reputation for it (Arkansas) is the extremely high consistency of some of the mining runs.

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Re: ZDP-189 - choosing the right waterstone

Postby dmiddleton » Mon Sep 08, 2014 10:52 am

it's funny you mentioned the Arkansas stones, as the reason i was asking about the base of the naniwa is i just found my Arkansas stone that has a wood base cracked into three pieces from the wood base having warped. i will not be investing in anything with a wood base in the future. fortunately a couple of the pieces are still big enough to use and the small piece works well as a "nagura" stone for cleaning my other stones and it is absolutely flat as that is one of the slowest wearing stones i've ever used.

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Re: ZDP-189 - choosing the right waterstone

Postby Cliff Stamp » Mon Sep 08, 2014 11:00 am

That is one of the issues with wood bases for stones which are soaked, or just left damp as even stabilized woods do not like exposed to repeated water/drying. I use wood blocks on stone all the time though however I just put huge blocks on and don't actually soak them, just the stone. The new waterstones however are often getting quite picky in how you have to treat them. The Shapton Pro line in particular is extremely full of warning about all the things which can damage the stone. Interestingly enough, the cheaper lines like the King/Bester are pretty much invulnerable to harm short of soaking them in water until they are saturated and then freezing them.

The Japanese in general have a massive line of stones, that pile I bought recently only looks at a very small grit range (100 to 400) and even then I got maybe 15-20% of what is available in various lines/brands of waterstones. There is also not much information on it unless you can read Kanji. There are in fact so many types/styles of Japanese waterstones it is similar to how many types of steels are used in Western knives. Often when people complain about them, it is because they are using a stone which isn't designed for the type of steel they are using it on or the amount of pressure being put to the stone. But this kind of information isn't trivial to find.

I will probably put up the stones I have in a passaround once I work with them all as it isn't like I need over a dozen low grit stones, at most 2-3 are needed and I think I will end up reducing it to 1-2.

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Re: ZDP-189 - choosing the right waterstone

Postby The Mastiff » Tue Sep 09, 2014 1:33 am

Excellent photography. Good information as well.

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Re: ZDP-189 - choosing the right waterstone

Postby WorkingEdge » Tue Sep 09, 2014 11:17 am

Great info, Cliff. Regarding Shapton Pro's, what is your opinion of them? I bought a series of them based on micron size as opposed to what type of steel they were meant for. I have used them to sharpen various steels including ZDP and other high carbide steels without too much hassle.

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Re: ZDP-189 - choosing the right waterstone

Postby Cliff Stamp » Tue Sep 09, 2014 11:37 am

WorkingEdge wrote:Great info, Cliff. Regarding Shapton Pro's, what is your opinion of them?

I have used a Shapton Pro 120 :

http://www.youtube.com/watch?v=3ABYFdjA ... lpVGcKd1vQ" target="_blank

It really needs low pressure to work well without excessive dishing/wear/mud. I have the Shapton Pro 220 which I will be using shortly which is supposed to have the exact opposite problem.

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Re: ZDP-189 - choosing the right waterstone

Postby Matus » Tue Sep 09, 2014 1:49 pm

I do not know how well known are here shops like japaneseknifeimports (USA) or japanesenaturalstones (Denmark), but their own water stones - Gesshin and JNS are really great. My personal pick would be JNS300 (excellent, slow dishing coarse stone, splash&go), followed by Gesshin 2000 (incredible stone, needs to be soaked) and then either Gesshin or JNS 6000 stone (both splash and go). One could also add the JNS800 which is absolutely wonderful oversized stone.

I have used all of the stones mentioned.

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Re: ZDP-189 - choosing the right waterstone

Postby Cliff Stamp » Tue Sep 09, 2014 5:16 pm

Matus wrote:My personal pick would be JNS300 (excellent, slow dishing coarse stone, splash&go)...
That looks interesting, how does it cut/wear compare to the common King, Norton, etc. 200 grit stones?

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Re: ZDP-189 - choosing the right waterstone

Postby Matus » Wed Sep 10, 2014 5:15 am

Cliff Stamp wrote:
Matus wrote:My personal pick would be JNS300 (excellent, slow dishing coarse stone, splash&go)...
That looks interesting, how does it cut/wear compare to the common King, Norton, etc. 200 grit stones?
I found the stone rather slow wearing compared to for example Gesshin 400. I have made some point clipping on one knife where I filed off some 5mm from the tip away (to give it a bit of 'honesuki' shape) and it barely left any traces. One more positive note - since the stone is splash&go and not a soaking one, it is not 'thirsty' during sharpening so you do not need to keep adding water as compared to soaking coarse stones.

I have not used the King or Norton, but if the Norton is one of their 'glass' series, it should be very hard and slow wearing too.

One hears a lot of good comments on Beston 500 which should be fast stone, but also fast wearing. Another option would be Chocera stones - they have very good reputation too.

One side note on soaking stones - the coarser the stone, the faster flows the water through it and so you need to keep wetting the surface during the sharpening. Example - my Gesshin 400 needs adding water much more often than the Gesshin 2000. Also - soaking stones will need 4-5 days to dry under normal conditions, while splash&go stones dry within 24 hours. As a proper physicist I did a measurement on that :)

If you want to find (way) more information on water stones, than have a look at http://www.kitchenknifeforums.com" target="_blank

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Re: ZDP-189 - choosing the right waterstone

Postby Cliff Stamp » Wed Sep 10, 2014 6:48 am

Matus wrote:
If you want to find (way) more information on water stones, than have a look at http://www.kitchenknifeforums.com" target="_blank
The problem is that while there is a lot of information it is difficult to impossible to interpret. If I tell you that a stone is soft or muddy for example what do you know really? It is like if I tell you that my kid runs track "fast". Now what do you really know, and how certain can you be of it? I am working on stones now and finding that even the simplest questions have really non-trivial answers. For example this appears to be a simple question - how fast does a stone cut? But it actually depends on the steel, force and amount of water used. By this I mean that you can have two stones and the which one is faster depends on those attributes. If you apply a high force one stone cuts faster but if you apply a low force the other cuts faster. Similar changes can be made if the steel or amount of water changes. Thus how do you answer that simple question in a meaningful way?


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