What is ceramic?

K

Knyfe

Joined
Nov 4, 2007
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I thought I knew: that white or grey vitreous material like the rods from Idahone or the Sharpmaker, or the bottom of the coffee mug.
I assumed it could be made into a rectangular shape like a whetstone, and I’m pretty sure some companies do it. Like Spyderco DoubleStuff or Benchstone. Maybe some others. I think it is clay that is baked in a kiln.
Then I got looking at AliExpress, and I found inexpensive Hiamea “Ceramic Whetstones.” Just the thing for a cheap guy. I posted in reddit seeking opinions. The only person who responded said:

“its not a ceramic stone, its just a cheap chinese waterstone. probably exactly the same as dozens of other examples on amazon “

That confused me. Is it a water stone, or a ceramic stone, or … both?
More investigation . . . sharpeningsupplies.com says there are water stones, oil stones, and diamond stones.
However, if you dig deeper, they say there are also “Ceramic Stones” and “Ceramic Water Stones,” although they also say this is “definitely a source of confusion” and indeed, their explanations left me confused.

So I guess a good place to start would be, can someone explain to me the difference between a Water Stone, a Ceramic Water Stone, and a Ceramic Stone, and how can you tell which you are buying?
And, what are King Whetstones or Shapton Kuromaku?
 
My understanding, probably wrong, is that a waterstone is an abrasive, usually alumina oxide, in a water-soluble matrix. A ceramic waterstone is ceramic abrasive in a water-soluble matrix. The ceramic waterstone should be more aggresive and maybe handle harder steel.

A ceramic stone is the Shapton glass stones or Spyderco bench stones etc, some baked clay concoction that is really hard!
 
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I will leave the definition of ceramic to others. But I do share your respondent's recommendation that you steer clear of cheap Chinese synthetic waterstones.

King is a Japanese company that has been making waterstones for a long time. If you want a bargain, here's where to find it: an inexpensive but excellent line of stones. I used the 800 and 1200 extensively back when I did woodworking (badly) a few decades ago. Drawbacks: you have to soak them, and they dish readily and have to be flattened. But they are really good stones.

Shapton is another Japanese stonemaking company, and my favorite. The Kuromaku line is also known as the Pro line, and they are very very good stones. Splash and go, no soaking. Reasonably speedy. Good feel. My preference is the Shapton Glass stones though.

Two other Japanese companies making waterstones at the same level as Shapton: Suehiro, Naniwa. Which you like depends on your personal preference, but even the most rabid partisan of one of the three would readily concede that the other two are doing good work.

Outdoors55 did an enjoyable and informative video about the most popular of the cheap Chinese waterstones, the Sharp Pebble:
 
A water stone might have many formulations. Some, like the Shapton Pros, are ceramic. Others, like King's primary line, are not. It just means that it's meant to be used with water.
King Neo stones sure feel like ceramic and the Naniwa Pro/Chosera are held together with magnesia salts.
 
Ceramic is a very misunderstood term in general, but specifically with whetstones.

The vast majority of water stones are ceramic stones. It refers to the abrasive.

Aluminum oxide and silicon carbide are both ceramics.

Shapton Glass, Shapton Pro, King water stones, Naniwa Chosera, Naniwa Super stones are all ceramic stones. So are most of the cheap chinese water stones that use a soft resin bond with aluminum oxide. As are the cheap coffee mugs made up of mostly aluminum oxide(albeit a slightly different compound to what most good stone manufacturers use)

Whether it is a good idea to buy cheap chinese water stones doesn't have anything to do with the question of are they ceramic or not.
 
Hey,
Searching a little bit about the topic as I want to make my own wheel with home made abrasive paste on it, I wonder what are difference between those abrasives :
- Corindon : or Aluminum Oxide. Seems like there is mainly brown and white category, brown being less pure. It is not too much britle and good abrasion. I guess most belt named aluminum oxide are with the brown one.
- Silicon carbide : very abrasive but break easily, to be use with less pressure
- Zirconium Oxide : Another kind of abrasive used versus Corindon. Seems to accept more pressure, so maybe less brittle.
- Ceramic (some belt like 3M cubitron use that name) : don't know what is it. As Aluminium oxide or Silicon carbide are both ceramics, is it one of them, just purer or different process to make them, so maybe the white aluminum oxide ?

Anyone got some info about that ?
 
I apologize in advance for answering your post without addressing your specific question. The word more commonly used in English for the first abrasive is corundum. Just wanted to head off possible confusion.
 
You can also buy genuine diamonds (big ones!) for a dollar each, and solid gold for a little bit of nothing!
It seems that truth in advertising is unknown in China.
( They also sell "genuine" Bill DeShivs knives, BTW.)

If you are going to buy anything from there, you are doing it correctly-try to learn as much about the item as possible, and hope that at least some of the copy is true.
 
Ceramic, from a scientific standpoint, means a material that is neither organic nor metallic, and can be crystalline, glassy, or both. Whoever, it can mean a number of things with sharpening stones:

•The abrasive (most abrasive grains are ceramics)
•The bond (vitrified stones are a ceramic bond, as opposed to resin, shellac, metallic, etc.)
•As a subset of the above, many people refer to sintered ceramics, which are ceramic grains fused via enormous heat and pressure into a single solid form without any binder, merely as "ceramic" stones, though this is technically shorthand, and often leads to confusion.

Water stones and oil stones just refer to the kind of lubrication that is recommended by the manufacturer to be used with them. In the case of water stones, some are made using a urea formaldehyde resin, which is water soluble, and these are what are typically referred to as "splash and go" stones, and should not be soaked, as it would dissolve them. Those stones would be ruined by oil, as they are very hard when not subjected to water. Vitrified bond water stones generally are a very soft bond such that water is all that is needed as a lubricant since it sheds grit so readily that surface grains come off before being fully worn down. Oil stones are usually a hard bond and the greater friction of water or dry use will lead to glazing of the stone, with the higher lubricity of the oil preserving the sharp edges of the abrasive grains, keeping them cutting instead of rubbing.

Diamond stones are just a class of abrasive grain type and come in several different formats, but the most common is as a plated metallic coating, which has fairly high grit protrusion and performs like a coated abrasive like sandpaper would--namely that higher grit protrusion will lead them to cut more aggressively for their given grit rating compared to a bonded abrasive. But diamonds can also be found in metallic bond, vitrified bond, and resin bond. Those methods are more typically used in industry rather than knife sharpening as they are very expensive due to how much more diamond grit they use, even in thin layers.
 
FortyTwoBlades said:
Ceramic, from a scientific standpoint, means a material that is neither organic nor metallic, and can be crystalline, glassy, or both. Whoever, it can mean a number of things with sharpening stones:

•The abrasive (most abrasive grains are ceramics)
•The bond (vitrified stones are a ceramic bond, as opposed to resin, shellac, metallic, etc.)
•As a subset of the above, many people refer to sintered ceramics, which are ceramic grains fused via enormous heat and pressure into a single solid form without any binder, merely as "ceramic" stones, though this is technically shorthand, and often leads to confusion.

Water stones and oil stones just refer to the kind of lubrication that is recommended by the manufacturer to be used with them. In the case of water stones, some are made using a urea formaldehyde resin, which is water soluble, and these are what are typically referred to as "splash and go" stones, and should not be soaked, as it would dissolve them. Those stones would be ruined by oil, as they are very hard when not subjected to water. Vitrified bond water stones generally are a very soft bond such that water is all that is needed as a lubricant since it sheds grit so readily that surface grains come off before being fully worn down. Oil stones are usually a hard bond and the greater friction of water or dry use will lead to glazing of the stone, with the higher lubricity of the oil preserving the sharp edges of the abrasive grains, keeping them cutting instead of rubbing.

Diamond stones are just a class of abrasive grain type and come in several different formats, but the most common is as a plated metallic coating, which has fairly high grit protrusion and performs like a coated abrasive like sandpaper would--namely that higher grit protrusion will lead them to cut more aggressively for their given grit rating compared to a bonded abrasive. But diamonds can also be found in metallic bond, vitrified bond, and resin bond. Those methods are more typically used in industry rather than knife sharpening as they are very expensive due to how much more diamond grit they use, even in thin layers.
Click to expand...
Thanks a lot for those details ! So I guess the ceramic abrasives in cubitron are a homemade receipe of ceramic baked and pressured, something different than corindon or sic.
 
milangravier said:
Thanks a lot for those details ! So I guess the ceramic abrasives in cubitron are a homemade receipe of ceramic baked and pressured, something different than corindon or sic.
Click to expand...
Cubitron is a structured aluminum oxide. So the abrasive type is aluminum oxide but the grade of that aluminum oxide is Cubitron. The abrasive grains are created via a process that causes them to form sharp little triangles, and those triangles are electrostatically aligned during the bonding process so they stand on edge, presenting their points to the work. This is part of why grain shape and structure matter in addition to the grit size and material composition.
 
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