Thread: Reasons I feel hones have to be sedimentary

Please correct me if I'm wrong, argue with me, but as we all search for new stones, some people are considering things like Jasper... (?) and I think this is largely wrong/highly labour intensive. After seeign this in two or three threads, and posting in both I thought it might actually be better to post it in it's own thread for discussion, so that before we all go out and find some mineral with Mohs hardness 9.9999 and more common than air, we find out what is important to a hone. Please read:

I"m just tossing my two cents out there for the world. Thinking about the mineralogy and material properties, shouldn't all hones necessarily be sedimentary rock? My thinking is this:
Hard particles in a soft substrate is like sandpaper that refreshes itself. If you have one hard thing it is like a chisel or a knife or a grater. Think about this on an extreme level. If I have a stone with a profile like this /\/\/\/\/\/\/\/\/\ and it is a single hard stone that is harder than steel, it's gonna cut gouges in the steel equal to that, and never really smooth out. Think cheese grater. If those cutting peices are glued together with something softer, they will break off and smooth out. Where this "glue" is soft, like coticule, it will continuously refresh itself, and cut a lot faster with a slurry. When this "glue" is hard, the cutting particles will eventually smooth out a little, like a J-nat. When this glue is solid, or if the crystalline structure is solid, the grit has to be built in. All sandpaper is alumina or SiC or whatever, just different size pieces. Or DMT. The diamonds are the hardest thing known to man, and the way they get different grits is not by changing the hardness or mineral properties of the diamond, but the GRIT of the diamond they embed. So while Jasper (or quartz or tigers eye or cats eye or corundum or diamond or sapphire or ruby or hawks eye or feldspar or topaz or chrysoberyl or chromium or boron or beryl... you get the idea) is harder than steel, that is not important. Its the finish you put on it that will be important. Lapping with a DMT XX will give you a rough hone, lapping with a DMT C a smoother hone, DMT F a smoother hone yet, etc etc. And the grit will not correspond, ie, lapping with the DMT C (325 grit) doesn't mean your jasper hone will be a 325 grit hone, just rougher than if it were lapped with the DMT F (1200). My best guess for this success is if by trial and error through different lapping treatments you came up with a progression, or if you only made one rock, you made is smoother than glass (very literally) to be used as a very final polisher, probably around some astronomical grit, as it wouldn't do any honing, only polishing.

The evidence I'm guessing behind all this is:
-All man made rocks are sedimentary- SiC or alumina or something harder than steel, BOUND BY something softer than steel, polymer, clay, ceramic, etc.
-The exception to this is carbo stones, because carborundum is harder than steel, and we all know what a bitch it is to lap a swaty or a carbo. If you look closely at them though, they are not a single crystal, and I suspect they are sedimentary in nature, where the sediment is SiC powder (SiC is commonly known as carborundum)
-Grit and Hardness have no correlation- all DMTs are diamond, SiC sandpaper comes in all grits
-If something is harder than steel (roughly 7 or higher on the Mohs scale) steel will do little to wear it down, and it will EAT steel (try taking a coping saw to a DMT)
-If something is softer than steel (roughly 6 or lower on the Mohs) it will barely touch steel and steel will just wear it down. (try cutting steel wire with a knife shaped piece of shale)
-All confirmed location hones to date are sedimentary- Thuringens, Coticule, BBW, J-nat, the British Isle shales, Arkansas, Turkeys, etc.
-While Sham's hone MIGHT be jasper because it LOOKS like Jasper, until it is evaluated by a minerologist I'm skeptical. To me it looks like a sedimentary rock, just not with clear striations. If you want I can post pictures of limestone or a piece of shale I use as a paper weight, neither show striations, both are sedimentary. Olivia, please can you ask your brother about this?
-Diamond paste is all ground up diamond, just in different sizes, and the size determines grit
-IIRC Shapton Glass Stones are only mounted on glass, they are actually polymer bound (sedimentary again), why wouldn't they just make a hone out of Silica Glass (SiO2, same as quartz)?

So as a summary, we need a sedimentary rock, with a water soluble base softer than steel, and cutting particles harder than steel. While igneous/metamorphic/crystalline minerals and rocks can work... I don't see the practicality in having to have 10 slabs of them, all lapped differently (and probably inconsistantly I might add, given natural variance)

In theory any mineral harder than steel will wear steel and can be considered as a honing medium. However its way more complicated than that. Even softer stones can be used to hone. Remember the Grand canyon was formed from running water (in general) and granite will fall apart to mud and sand when exposed to weathering.

really its the type of particales, (minerals) the particale size and shape and the base rock that all plays a factor. I would think using a massive rock like say slate or a chunk of quartz as a hone might very well work to hone an axe or do preliminary honing but for finishing and for delicate work with our razors I'm not sure it would. Of course there are some non sedimentary rocks that are quite soft. I guess you can experiment with stuff like marble or fluorite or apatite or asbestos based rocks or talc and see what happens. If you use the stuff and its softer than steel it will work the way our usual hones work anyway by having the residue break off and becoming smaller and smaller like a slurry so...

Thats what I'm saying... You have to have hard particles to actually cut... The medium of the stone can be anything though. If its a solid, smooth crystal... how can it cut? Thats my main question.

I've alerted Howard Schechter to this thread. I'm interested in what he has to say on the subject and I'm interested in this subject in general.

Chris L

Well, if it's a really hard stone--much harder than steel--and pure, then won't the stone work like a diamond plate, basically? Rather than particles breaking up and doing honing, it will be a very hard surface that takes the finish that you give it and KEEPS it?

Isn't this, in fact, how the spyderco hones work?

I'm no geologist and what little I know on this topic I've learned on the forum from posts by Bart, Blaireau, and Howard among others. What Karl is saying goes along with the accounts I have read about why the coticule and the Escher families of stones cut razors so efficiently and effectively. It does seem that hones in general (naturals) are all from sedementary rock and that the synthetics mimic them in their construction. Interesting thread.

I'm not saying solid hard stones won't work, I'm just saying they'd be a pain cus you'd have to lap the grit into them, and that you would have no way of knowing what that grit is except by guess and check. And you'd have to find a way to refresh that grit, because as it seems is common sentiment, DMTs do slow down, not become finer, but become less aggressive. So if we're talking something not as hard (and therefore as durable) as diamond, something closer to steel, as say, jasper, is, it'll settle down much faster, so you'd have to keep reapplying your surface to the hone. I have to emphasize that I doubt the grit would get finer, just a lot slower. Unless it were a final finisher and as smooth as glass, in which case this is a good thing, but ultra ultra slow. Someone on B&B made a jade hone and I dunno if they realise it, but they simply just made a stone buffer. The edge they got is highly mirrored, and its very very slow. So basically its not cutting, just slowly slowly polishing. I'm interested to hear Howards take on this.

And someone pointed something out to me, as a counterpoint but I really think it is a "co-point", there are some sedimentary stones were the sediment does the cutting, there are no cutting particles, ie, Arkansas stones. I feel this happens because the sediment bond is not as good as a crystaline bond, so the pieces of sediment are continuously breaking off from each other.
This is I guess illustrated in the difference between conglomerate and say, limestone. (exaggeration, conglomerate incorporates pebble sized particles, where limestone is almost homogenously CaCO3). One is clastic sedimentary rock, ie, it has discrete particles bound by something else (see escher, coticule), the other is biochemical sedimentary rock, formed by the chemical deposition of ions coming out of solution or the breakdown of organic matter (see arkansas). Many clastic rocks have biochemical sedimentary cement, typically limestone or clay.
Typically we would be interested in Shales (escher, coticule, anything from the UK) as they are defined as clastic sedimentary rocks with a particle size less than .002 mm, ie, less than 2 microns. However, some silt stones would be fine for rougher grits, defined as .002mm to .063mm, ie 2 to 63 micron.
Now if memory serves, clasts (the particles) are typically harder rocks, typically quartz (as is the case with thuringens I believe) but also things like feldspar, garnet (coticule) corundum, etc. This mixes with a cement material (lime, oil, softer rocks that were weathered even finer, organic matter) and forms a clastic rock.
On the other hand, some rocks can form from the deposition of bio matter, then through decay, deposition and pressure, became organic/biochemical sedimentary rocks, now we have what I believe formed the J-nats and arkansas stones. I am not sure what the cutting particles here would be butting I'm guessing oxidized metals- Al2O3 and the like, maybe some silicates (SiO2). I believe most organic depositions are carbonate minerals (CO3- like chalk, limestone) which I believe is quite soft so I doubt that does the cutting. Anyway, hopefully a real geologist will chime in, this is just what I remember learning from my grandfather.

In my hone hunt, I have forgone hard minerals. I am now trying to track down where I might find quartz clasts in the shale around Ithaca. We have deep gorges (and I live literally on the edge of one) that expose hundreds and hundreds of layers of rock, so hopefully a few will be usable. We'll see. I chose quartz cus its the most common, but really any hard, fine clasts should do.

Hmm, good points Khaos!

The arkansas honning stone is one of the few natural stones out there that claim to have a progression of stones...ie., wa****a, soft, hard, true hard, black hard and translucent...they are currently graded by color and density.
They are primarily made of novaculite, whose crystaline structure is claimed, to range from 2-5 microns in size.

Based on my interpretation, of what your saying, truely the 'performance' grading should be done not only by density and color, but by the substrate(sediment) bonding material that holds the novaculite(crystaline structure) together? Since this substance is what determines how easily the novaculite crystals are released, while honing.

Most likely the density/honing capabilities, of the various stones is determined by this substrate (sediment,) rather than the novaculite itself?

Great thread, btw.

Thanks,

Mac