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#1 locutus

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Posted 06 September 2013 - 02:13 PM

Good morning, ladies and gentlemen.

 

I am a knife sharpener.  As many of you probably know, ceramic "stones" and rods are used in knife sharpening.

 

Have you ever made one?

 

The most popular ceramic sharpeners are made by Lansky, the "Crock Sticks," and Spyderco,  the "Sharpmaker."

 

These are quite expensive.

 

My mother had a kiln and dozens of molds 40 years ago, and was very much "into" the cermics hobby.

 

It occurred to me that anyone with a kiln and knowledge could make these devices.  I have read that the clay used to make the slip is "Zirconia."

 

I would appreciate a buit of your expertise here.  Cuold any ceramic hobbyist make these sharpeners?  Is the Zirconia difficult to obtain?

 

These are unglazed, and the sharpening ability is controlled by surface texture, rather than grit size as would be the case with corborundum.

 

I assume the surface texture of an unglazed cersmic is controlled by the preparation of the green ware, but I could be mistaken here.

 

Thank you in advance for any information.



#2 JBaymore

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Posted 06 September 2013 - 02:51 PM

I don't know the specifics of knife sharpening stones... but such specialized "zirconia ceramics" is (as a generality) very technical formulation work, to my knowledge. Beyond the capabilities of most studio ceramists I'd be guessing, both in the engineering and materials processing knowledge as well as in the firing controls likely necessary for production.

You are into the realm of "technical ceramics" there I think.

So not impossible..... but you'd likely have to be doing a lot of research, and unless you were producing in volume........ likely ccheaper and simpler to just buy existing ones.

I am an Iaidoka, and for sword sharpening typically high quality natural stones are used. Only real experience I have with "sharpening".

best,

.............john
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#3 locutus

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Posted 06 September 2013 - 04:27 PM

I don't know the specifics of knife sharpening stones... but such specialized "zirconia ceramics" is (as a generality) very technical formulation work, to my knowledge. Beyond the capabilities of most studio ceramists I'd be guessing, both in the engineering and materials processing knowledge as well as in the firing controls likely necessary for production.

You are into the realm of "technical ceramics" there I think.

So not impossible..... but you'd likely have to be doing a lot of research, and unless you were producing in volume........ likely ccheaper and simpler to just buy existing ones.

I am an Iaidoka, and for sword sharpening typically high quality natural stones are used. Only real experience I have with "sharpening".

best,

.............john

 

Thanks, John.  that's the kind of information I was looking for.

 

Not giving up yet,but will start doing some more research

 

I currently use a large selection of both man-made and natural stones, just as a polisher does.  This is new territory for me, and exciting.  I also use the Lansky "Crock Sticks" for minor tough up work, and they are very satisfatory.  I'm trying to find a way to use the ceramic tools for the "heavy work" work as well.



#4 PeterH

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Posted 06 September 2013 - 04:28 PM

locutus,

 

Fair question, but I think it's a non-starter. Zirconia is not a clay, and is highly refractory and totally non-plastic.

 

Looking at an abstract on sintering dental zirconia:

http://www.ncbi.nlm....pubmed/23107238

... you will see that it is fired to 1500 degrees centigrade.

 

Very few pottery kilns fire above 1300 degrees centigrade, so you have no way of reaching these temperatures.

 

Regards, Peter

 



#5 locutus

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Posted 06 September 2013 - 04:30 PM

 

I don't know the specifics of knife sharpening stones... but such specialized "zirconia ceramics" is (as a generality) very technical formulation work, to my knowledge. Beyond the capabilities of most studio ceramists I'd be guessing, both in the engineering and materials processing knowledge as well as in the firing controls likely necessary for production.

You are into the realm of "technical ceramics" there I think.

So not impossible..... but you'd likely have to be doing a lot of research, and unless you were producing in volume........ likely ccheaper and simpler to just buy existing ones.

I am an Iaidoka, and for sword sharpening typically high quality natural stones are used. Only real experience I have with "sharpening".

best,

.............john

 

Thanks, John.  that's the kind of information I was looking for.

 

Not giving up yet,but will start doing some more research

 

I currently use a large selection of both man-made and natural stones, just as a polisher does.  This is new territory for me, and exciting.  I also use the Lansky "Crock Sticks" for minor tough up work, and they are very satisfatory.  I'm trying to find a way to use the ceramic tools for the "heavy work" work as well.

 



#6 locutus

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Posted 06 September 2013 - 04:42 PM

locutus,

 

Fair question, but I think it's a non-starter. Zirconia is not a clay, and is highly refractory and totally non-plastic.

 

Looking at an abstract on sintering dental zirconia:

http://www.ncbi.nlm....pubmed/23107238

... you will see that it is fired to 1500 degrees centigrade.

 

Very few pottery kilns fire above 1300 degrees centigrade, so you have no way of reaching these temperatures.

 

Regards, Peter

You're probavbly right, Peter.

 

The way this got started, 25-30 years ago a power company lineman found that he could sharpen his pocket knife with a broken ceramic insulator he found along the line.  He mentioned it to some friends that were intrigued with the idea and started experimenting.  Shortly thereafter, Lansky "Crock Sticks" were born.

 

I have sharpened a small fixed blade knife on the bottom of a coffee mug. (The unglazed ring)  It was a lot of work, and the results were rather crude, but it would cut fairly well.

 

This is intriguing to me.

 

I wish that I still had all of my mother's old equipment to experiment with.



#7 PeterH

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Posted 06 September 2013 - 04:57 PM

locutus

The way this got started, 25-30 years ago a power company lineman found that he could sharpen his pocket knife with a broken ceramic insulator he found along the line.

 

Sadly the electrical porcelains are also fired to temperatures way beyond "craft" kilns. Try repeating the experiment with

a bit of porcelain, some of these are within the high-fire pottery range.

 

Regards, Peter

 

Ever so loosely related. When they started putting telegraph lines across the Australian outback, they kept having to replace

missing [glass?] insulators. They eventually realised that the indigenous people were "mining" them to make "flint" tools. They

they started putting a small pile of spare insulators at the bottom of the telegraph poles, so the in-service insulators were left

alone.



#8 locutus

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Posted 06 September 2013 - 05:42 PM

That's an interesting bit of history, Peter! :D

 

I will try to re-do my little experiment with porcelain. (Probably the next time my wife breaks something in the kitchen :rolleyes: )  IIRC, my mother didn't make any porcelain pieces.  I never really questioned it, but I guess her kiln wasn't up to it.

 

Her best friend worked in porcelain alomost exclusively, and I do remember mom talking about the possibility of "getting the stuff" needed to work in porcelain.

 

It's amazing how much there is to learn about little everyday things that we  take for granted.  A whole new world opens up when you dig just a little below the surface of almost anything.! :o



#9 Idaho Potter

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Posted 06 September 2013 - 07:45 PM

Back when I was a woodcarver, I sharpened my own tools, and for the most part used regular sharpening "stones" that either used oil or water to remove the metal filings.  Over time, I found I liked man-made "stones" best because they sharpened faster and gave a good edge to the tools.  I own a ceramic stone--white--that can put a great edge on a flat beveled chisel, but don't think there's any way this could be done in a pottery studio.  The stone is white ceramic approx two inches by six inches by almost one and a half thick.  Surface testure is really fine, and I used it primarily for my detail chisels.  I also have a ceramic "stick" for kitchen knives, but it is brown with a coarser texture.  Whatever you use, make sure you are either using oil or water to flush the metal filings away so you don't nick the edges of any tools.

 

Shirley



#10 Biglou13

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Posted 06 September 2013 - 08:21 PM

I've used the bottom of some ceramics to hone a knife back..... More so akin to steel (Ing).

The most technical hand sharpening I've seen is on a piece of granite very flat. And wet sand paper

Much to to techie for me but have tried it. I'm still satisfied and can get my high carbon steel chef knives to shaving sharp. Which is more than enough for me.

I have a very specific japanese wet stone. And won't touch my knives to any thing else.
It has a specific grit and softness to my liking and the knives, and it took years to find the right one. i have have thoughts like yours but in.making a stone.

I think the stick will be problematic but if you made rectangles with same idea production would be easier.

And depending an knife steel, I think the range of pottery to make abrasive device is within the cone 6 or less realm. Mind you a I prefer a softer stone it equals longer lifespan of knife.
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#11 locutus

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Posted 06 September 2013 - 08:27 PM

I clean my "Crock Sticks" with an old toothbrush and Barkeeper's friend.  Seems to work well. I don't use them very much though.  Mostly use Japanese waterstones and J-Nats.



#12 justanassembler

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Posted 07 September 2013 - 12:47 AM

I knew someone who worked on the production of spyderco's ceramic sharpening system, they are zirconia ceramic, created using a spray drying process, pressed, and sintered to cone 32.



#13 Bob Coyle

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Posted 07 September 2013 - 11:37 AM

Steel is softer than most high fired clays so I think you would be able to "sharpen" knives on any flat, unglazed high fired of porcelain. The trick would be to get a uniform grit size on the porcelain surface to give a smooth finish. You could probably slip it and make a pretty good sharpener.



#14 MMB

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Posted 07 September 2013 - 09:42 PM

I know that chefs can sometimes sharpen their knives on the bottoms of plates. Slip casting I would agree would provide a smooth finish. You could also do what Jeff Campana does to the bottoms of his work using tools from...

 

http://www.toolocity.com/ Quality Diamond Tools for Polishing Granite, Marble and Concrete

 

...he polishes them down to a 3000 grit glassy finish. You dont have to polish that high but I think you can catch my drift.

 

As for reaching 1500 degrees celsius it could be possible at home, not with a hobby kiln, but with Kaowool. Good ol ceramic fire blanket. Its easy to find there 2400 degree fahrenheit blanket but I have seen one blanket type that has a 2800 degree fahrenheit (1500+ celsius) tolerance. Maybe search around for that then build a small efficient gas kiln. Propane shouldnt be an issue, but if you want you could make a waste oil burner for higher BTU output.

 

It seems possible and might end up being a eventual business venture if you find success. Discount handmade knife sharpeners.

 

Although, dont most higher temp industrial ceramic applications not use "wet" clay but instead sinter the powders?



#15 JBaymore

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Posted 07 September 2013 - 09:54 PM

Although, dont most higher temp industrial ceramic applications not use "wet" clay but instead sinter the powders?


Lots of dry pressing these days....only a couple percent moisture content to the mixture.....no "clay" as we think of it in the mix .....still alumino silicate based... so "ceramic". Just no chemicaly combined water in the mix to speak of. The pressure causes that tiny bit of physical water to evaporate... works dry when the press opens.

best,

............john
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Professor of Ceramics; New Hampshire Insitute of Art

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#16 locutus

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Posted 08 September 2013 - 09:48 AM

Wow. Lots of expertise here! :)

 

I would never have considered dry pressing!  Makes sense though.  Presure creates heat.



#17 JBaymore

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Posted 08 September 2013 - 11:32 AM

Wow. Lots of expertise here! :)
 
I would never have considered dry pressing!  Makes sense though.  Presure creates heat.


One of the biggest problems with ceramics is........ wait for it..... clay. Because of the genesis of its geologic forming....... it has some pesky annoying characteristics. Add to that the characteristics that mixing it with water to make it maleable add (like unev ern drying, solubles migrating, warping, etc.).... and it is a pain in the butt. (Just ask any potter.)

Clay in the wet form is not what interests most people.... it is the FIRED stuff that is very useful. So what industry has iften done is figure out how to get the FIRED ceramic... without using much if any PLASTIC clay. Studio artists are usually tied to foming processes that require the plastic nature of the body for forming. Industry can use production processes that remove this dictate from the equation.

Some of what is done in industry is simply amazing when compared to the typically studio artist's operations.



BTW,... compare the prices YOU charge to the prices that this kind of commercial ware is sold at. I'm guessing that you are underpricing your HAND work.

best,

..................john

PS: Lou.... there is a MOR test showing in a brief point toward the end of that clip.
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#18 locutus

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Posted 10 September 2013 - 09:18 AM

Thank you all very much.  I think this project will go on the back burner for the time being, at least. :)

 

I've already learned a lot from the nice folks here, and I've barely scratched the surface.






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