Arkansas Stones: Are They Still Considered Good?

[FortyTwoBlades]

Shape and friablilty play a bigger role then people give credit.

Here is SiC cutting a ceramic knife.


Shouldn't be possible if it worked on hardness alone

Ah, but silicon carbide is actually harder than zirconium dioxide. Like, roughly twice as hard. Aluminum oxide is harder than zirconium dioxide, too, though by a much smaller margin.

That being said, some degree of wear does occur to the harder of the two surfaces, which is why abrasive grains blunt through use in the first place.

 

[DeadboxHero]

Ah, but silicon carbide is actually harder than zirconium dioxide. Like, roughly twice as hard. Aluminum oxide is harder than zirconium dioxide, too, though by a much smaller margin.

That being said, some degree of wear does occur to the harder of the two surfaces, which is why abrasive grains blunt through use in the first place.

I've been pretty impressived with SiC lately, I've noticed that alumina won't touch CPM 4v at 64hrc but that SiC will.

 

[JD Spydo]

Ah, but silicon carbide is actually harder than zirconium dioxide. Like, roughly twice as hard. Aluminum oxide is harder than zirconium dioxide, too, though by a much smaller margin.

That being said, some degree of wear does occur to the harder of the two surfaces, which is why abrasive grains blunt through use in the first place.

Hey "FortyTwoBlades" I particularly want to thank you for the timely and relative information you've been kind enough to share with us on this thread about Arkansas Stones. I have a question and I'm sure you know the answer>> do you know of a website that has a Moh's Scale of Hardness on these abrasive materials we've been discussing on this thread? I know that there are websites out there on abrasives and their properties and hardness ratings but I'm just now aware of them and I figured you would know instantly where they are located.

I would sure appreciate anything you could share with us on that particular information.

 

[FortyTwoBlades]

Hey "FortyTwoBlades" I particularly want to thank you for the timely and relative information you've been kind enough to share with us on this thread about Arkansas Stones. I have a question and I'm sure you know the answer>> do you know of a website that has a Moh's Scale of Hardness on these abrasive materials we've been discussing on this thread? I know that there are websites out there on abrasives and their properties and hardness ratings but I'm just now aware of them and I figured you would know instantly where they are located.

I would sure appreciate anything you could share with us on that particular information.

I don't really care for the Mohs scale, since it's pretty macro in its values. Knoop, Vickers, or Brinell hardness is generally a better scale for rating hardness of abrasives against constituent materials of steels, I think. But you have to make sure you compare the right units!

I've been pretty impressived with SiC lately, I've noticed that alumina won't touch CPM 4v at 64hrc but that SiC will.

What'd I tell ya' about SiC?

 

[eKretz]

Yeah...pays to get the facts straight, lol. There are only a few abrasives harder than SiC. Off the top of my head, cubic boron nitride, boron carbide and diamond. There are a couple others also, but SiC is near the top of the heap.

Edit: oops! Didn't see that 42 had posted that chart. Notice the VERY wide disparity between diamond and all others. CBN is usually spec'ed at about 5000 on the Knoop scale. And regarding the factoid about even the harder surface wearing - definitely - even diamond plates wear from sharpening steel and lapping stones. And no it's not just the diamonds pulling out either. (Very tired of hearing that argument - spend some time researching with Google and you will see that yes they do wear).

 

[DeadboxHero]

I don't really care for the Mohs scale, since it's pretty macro in its values. Knoop, Vickers, or Brinell hardness is generally a better scale for rating hardness of abrasives against constituent materials of steels, I think. But you have to make sure you compare the right units!

What'd I tell ya' about SiC?

 

[JD Spydo]

Those new stones that Spyderco just made for their 204 Sharpmaker kit>> they are known as CBN which I was told is an acronym for "Cubic Boron Nitride">> didn't see it on any of those charts>> or am I missing it? Or does CBN go by another generic name? Because I've heard that on the Moh's Scale it's fairly close to diamond considering it's a man made material. Yeah we had those Vickers and Brinell Hardness units when I took a couple of metallurgy classes at a college here in Kansas City, MO where I live. We also had a Rockwell tester too.

I had heard of the Knoop before but didn't know much about it. Now I've always been told that "novaculite" which of course is what this thread is about is a type of compound of quartz related minerals. I hope I got that right because I haven't taken any geology courses as of yet but that's what I had the people from the "Washita" company tell me some time back anyway. I think I also remember that guy from the Dan's Whetstone company say the same thing too.

Also how close are novaculite and the Belgium equivalent known as "coticules" in hardness?

 

[eKretz]

Sometimes I wonder...

I just mentioned CBN. Literally two posts above yours J.D. - and also its hardness on the more useful scale. Moh's is not super useful in terms of relative hardness - more like a basic field guide. Novaculite is nearly 99.9% pure silica, or silicon dioxide. This is related to quartz, yes. The entire stone is composed of abrasive material.

Coticules are not homogenous like Arks, so you can't just rate their hardness by their abrasive content. They are more like modern water stones, with abrasive distributed throughout in a matrix of natural binder. The abrasive found in a coticule is spessartine garnet. The hardness of each individual coticule varies widely. Some are quite soft and will gouge readily with a careless knife honing stroke. Others are relatively hard - but as I already stated earlier - nothing like an Ark in terms of hardness. On most Arks you could sharpen a needle without gouging the stone much if at all and they do not vary much in hardness.

 

[Eli Chaps]

There is some outstanding information in this thread! Thank you eKretz and FortyTwoBlades!

 

[JD Spydo]

Sometimes I wonder...

I just mentioned CBN. Literally two posts above yours J.D. - and also its hardness on the more useful scale. Moh's is not super useful in terms of relative hardness - more like a basic field guide. Novaculite is nearly 99.9% pure silica, or silicon dioxide. This is related to quartz, yes. The entire stone is composed of abrasive material.

Coticules are not homogenous like Arks, so you can't just rate their hardness by their abrasive content. They are more like modern water stones, with abrasive distributed throughout in a matrix of natural binder. The abrasive found in a coticule is spessartine garnet. The hardness of each individual coticule varies widely. Some are quite soft and will gouge readily with a careless knife honing stroke. Others are relatively hard - but as I already stated earlier - nothing like an Ark in terms of hardness. On most Arks you could sharpen a needle without gouging the stone much if at all and they do not vary much in hardness.

That's extremely interesting about the "coticule" stones because I've had two Barbers that use straight razors both tell me that most Barbers rate those Coticule stones really good for straight razors. However I have had really great results using my Spyderco 302 Ultra-Fine benchstone on straight razors and some of these newer/better blade steels too.

I was told some time back that the actual abrasive compound that is in Novaculite (Arkansas stones) is almost identical to that of Coticules. I'm seeing now that is not accurate because based on what you've shared with us they are most definitely two totally different animals all together. As hard as natural diamond is and as great of an abrasive as it can be I'm really confused as to why there are not more rocks and minerals that could be used for sharpening stones. Because in the natural stone arena after diamond most natural abrasives are a very distant second and way back on most hardness scales.

Great information guys!!!

 

[FortyTwoBlades]

Well, a lot of that is because diamonds don't exactly make the habit of uniformly distributing themselves throughout a sedimentary substrate like silicon dioxide does. Naturally occurring abrasives each tended to have very different qualities and were only available in certain regions of the globe. As such, they were treated as a fairly precious resource and traded all over the world. You may find this an interesting read on the subject.

 

[JD Spydo]

Well, a lot of that is because diamonds don't exactly make the habit of uniformly distributing themselves throughout a sedimentary substrate like silicon dioxide does. Naturally occurring abrasives each tended to have very different qualities and were only available in certain regions of the globe. As such, they were treated as a fairly precious resource and traded all over the world. You may find this an interesting read on the subject.

That's extremely interesting because I also had a geologist from a local university here in my area tell me that there was a lot of novaculite deep in the earth and that the State of Arkansas is one of the few places on the continent that it's close enough to the surface to mine it and extract it. He also said that in places where they used to drill for oil wells there were times when their drill would hit a novaculite deposit and it would really wreak havoc on their equipment. The guy seemed to know what he was talking about>> he was also very well aware of coticule and seemed to have a vast knowledge of what rocks and minerals we have here in our area especially

I guess it's all kind of meaningless in a way because I truly think that the future of abrasives for whetstones for our hobby will be in the advancement of ceramics. And GOD knows we've seen some big advancements in that area in the past few years. I'm kind of at the point now where I'm probably just going to more or less give up on natural stones all together.

 

[FortyTwoBlades]

Eh...I think natural stones will always have a place as long as we have low-alloy carbon steels around. And we'll always have those. I rarely use natural stones, but they still work nicely to fill the role of a hard strop of sorts for certain tools.

 

[eKretz]

Yeah still quite useful for things like straight razors too - they produce some quite comfortable shaving edges. Also they are kind of fun to figure out in terms of what produces the best shaving edges. It's sort of neat knowing that you're using a stone produced by nature as well. And natural stones are quite unique from each other. Japanese natural stones in particular are quite unique, in that you use a slurry for honing - so its almost like loose grit lapping.

 

[DeadboxHero]

Eh...I think natural stones will always have a place as long as we have low-alloy carbon steels around. And we'll always have those. I rarely use natural stones, but they still work nicely to fill the role of a hard strop of sorts for certain tools.

There are some Sharpeners that are "Kasumi God's" on Instagram with those natural stones and simple high carbon steels.

Just jaw dropping beauty and skill.

Almost make me want to "jump ship" but my pragmatism refuses to let go of the higher performance offered by super steels and super abrasives.

 

[FortyTwoBlades]

I feel that once your sharpening competency reaches a certain point, ease of sharpening becomes more important than edge retention for most contexts. But that's ultimately a matter of personal preference. I find low-carbide or simple-carbide (chromium carbide) steels to give me the greatest overall satisfaction in the work I do.

 

[Blues]

I feel that once your sharpening competency reaches a certain point, ease of sharpening becomes more important than edge retention for most contexts. But that's ultimately a matter of personal preference. I find low-carbide or simple-carbide (chromium carbide) steels to give me the greatest overall satisfaction in the work I do.

QFT. There's just something...dare I say it?...peaceful and relaxing in the process.

Whether it's sharpening with the scythe stone after mowing the property...touching up a carbon steel Mora, or an old timey knife with blades of 1095.

They take a great edge and keep us in touch with tradition at the same time.

I like and own plenty of blades made with the super steels, but a large percentage of the knives I own are built with good old carbon steel.

 

[JD Spydo]

Eh...I think natural stones will always have a place as long as we have low-alloy carbon steels around. And we'll always have those. I rarely use natural stones, but they still work nicely to fill the role of a hard strop of sorts for certain tools.

Oh I plan on keeping all the natural stones I currently own and I feel like you do that there will always be some viable use for them even if it isn't sharpening blades I still feel like they are good for deburring jobs working with metal if nothing else.

 

[Obsessed with Edges]

I feel that once your sharpening competency reaches a certain point, ease of sharpening becomes more important than edge retention for most contexts. But that's ultimately a matter of personal preference. I find low-carbide or simple-carbide (chromium carbide) steels to give me the greatest overall satisfaction in the work I do.

That's what I've happily settled into, for the most part. Simple steels sharpen up and touch up in a breeze, whenever or wherever I happen to do it. Minimal fuss or worry about what tools may or may not be available to get the job done. Use whatever's at hand and it's done. Take the occasional opportunity to improvise a little bit in sharpening, using what you can find, and it still works. I like that.

 

[FortyTwoBlades]

QFT. There's just something...dare I say it?...peaceful and relaxing in the process.

Whether it's sharpening with the scythe stone after mowing the property...touching up a carbon steel Mora, or an old timey knife with blades of 1095.

They take a great edge and keep us in touch with tradition at the same time.

I like and own plenty of blades made with the super steels, but a large percentage of the knives I own are built with good old carbon steel.

For me it's purely a matter of pragmatism. Even super steels lose their peak sharpness quickly, still, and so if I want to keep it performing its best I still need to hone it fairly frequently. And a steel that gets back to screaming sharp with a couple of quick swipes on a stone ends up being more convenient for me overall.