Thread: honing variables

Basically, I'd like to see if we can create a comprehensive list of the differences between hones.

Harder to explain than just to do, so let me start:

1. size of the "grit"- i.e. how far apart the high points are on the hone's surface

2. grit shape - how round each high point is, i.e. would the surface look like a tub of marbles or a tub of sugar cubes

3. hardness - or how easily the cutting material abrades steel (diamond being the extreme, I reckon)

4. slurriness - how easily tiny bits break off to form a faster-cutting slurry

Not sure what else... maybe the prevalence of the actual cutting material in a given area? I mean, some hones (both natural and artificial) are composites, so the surface may look more like scattered marbles embedded in concrete than a tub of marbles.

Another perspective: if you looked through a microscope at the tiny scratch marks on an edge, you might imagine measuring them in several ways: how deep they are, how wide they are, how far apart they are, etc. - all of which might be able to be described in terms of the above 4 criteria (or others to be added).

Any thoughts? Please feel free to edit, correct, expound, etc. I know not all of these characteristics can be known about a given hone, but I bet some of the experienced honers around here have a pretty good feeling about how different stones might be characterized in such a manner. Ultimately, I guess I'd like a more concrete set of terms for talking about things like how "fast" a stone is, or how a lower-grit stone can be more of a polisher than a higher-grit stone.

Slurriness as you describe it would be two things. The first is friability. Silicon carbide is friable, i.e. large particles break up to form smaller particles resulting in a finer finish.

You could also have a sharpening medium that is nonfriable, but the individual cutting particles break out of the bond holding them firmly in the stone and mix with the lubricant (presumably and hopefully water) to form the slurry.

So maybe you might want to break that up into "slurriness" as you call it and "friability."

Then you have things like spyderco hones that don't really dish very much. Other hones, like a king waterstone, dish easily and need to be lapped often. Maybe that could be a variable.

Glazing is a factor on some hones. Some hones glaze over and don't cut very well. With the right individual with the right knowledge that could perhaps be made to be an advantage.

A big difference in hones is cutting speed. Arkansas hones are very hard and don't dish quickly at all, and that sounds advantageous until you find out that they are comparatively very slow.

Another aspect of a hone is the finish. an 8000 grit DMT hone doesn't shave like an 8000 grit Norton. Similar to how .5 diamond is much harsher than .5 chromium oxide.

Perhaps it would be good to list the hardness rating in Mohs of each abrasive. Diamond is to tool steel what tool steel is to sheet rock.

The "size of the grit" measurement is off, too. I have a DMT XXC that has diamonds that are about 120 microns in size. But you can see with the naked eye the amount of space inbetween some of the diamonds. If I have 120 micron diamonds but the "tips" are spaced on average 500 microns apart, then you have to list that, too. Perhaps changing size of the grit into Abrasive particle size and abrasive particle density would be helpful. EDIT: I see you put that in consideration in the paragraphs following the bold points.

Hone versatility is an aspect to consider. You can hone a razor from start to finish with a coticule, but not a shapton 16k. (well, not feasibly, at least.)

I could keep going but I have to go finish painting our guest bedroom.

Great! Friability gets added. Now we've got two criteria that aren't really words, but so what.

**EDIT: I take that back - friability is indeed a word, no matter what my spellchecker thinks.

Dishing, hmm. Don't really want to go there. As for glazing, that does affect a hone's action over time, but for simplicity's sake, let's assume a freshly lapped surface.

I think both finish and cutting speed might already be covered. In fact, explaining concepts like those is exactly the point of this whole endeavor. It could be helpful to look at them as a combination of several factors, such as using hardness, slurriness, and friability in the following example:

One particular fast cutter might be a stone with very hard particles (high hardness rating), that tended to give off slurry (high slurriness rating), AND whose particles didn't break up into smaller bits in the slurry (low friability rating). Another hone could also be a fast cutter, but in a different way.


To further clarify my mission statement: I'd like a set of variables by which most everything about the honing action of a hone could be expressed.

So far:

1. abrasive particle density- i.e. how far apart the high points are on the hone's surface

2. abrasive particle shape - shape of the high points, i.e. a surface like a tub of marbles vs. sugar cubes

3. abrasive particle size - perhaps how wide a groove it makes in the steel?

4. hardness - or how easily the abrasive particles cut steel (diamond being the extreme)

5. slurriness - how easily abrasive particles break off to form a faster-cutting slurry

6. friability - the degree to which the particles in the slurry break down into finer bits


Any more criteria?
Also, I'd love to hear anybody's breakdown of a particular hone according to these. You could do each criteria on a scale from 1-10 (least to most) or something.

Do you really think it is harder to explain than just do?

The details you are asking for -to be accurate- would take the capabilities of an extremely high tech laboratory with lots of specialized machinery

I guess it would be a cool thing to have for those interested. I just do the x pattern and the TPT and when it is feeling 'there' I strop and test shave. Whatever the size and shape of the particles doesn't concern me. How the hone performs is what I am interested in and honing the razor is how I figure that out. I am sure it would be good info for the SRP Wiki though.

Originally Posted by kevint

Do you really think it is harder to explain than just do?

The details you are asking for -to be accurate- would take the capabilities of an extremely high tech laboratory with lots of specialized machinery

When I said that, I simply meant coming up with the list of criteria, not finding the relevant data for any particular hone. I didn't have a good way of explaining what I wanted, so I thought I'd just dive in and start listing things so that people would see which direction I was going.

I know any real numbers for a hone would be tough to measure (though sticking some slurry under a microscope would be simple enough). However, I feel a lot of these things could be inferred from the way the hones perform. Heck, we infer a bunch of this stuff already, but we talk about it using (what I feel are) kind of vague, non-specific terms.

I see what you mean. thanks

Moh's hardness? Here is a graph http://www.gly.uga.edu/railsback/Fun...Trends29IL.pdf
(Apatite is the mineral your teeth are made of)

Here's a thread on Knife forums talking about abrasives and their hardness. Why 1 or .5 microns? - Knifeforums.com - Intelligent Discussion for the Knife Enthusiast - Powered by FusionBB

In whetstones though "hardness" generally does not mean the hardness of the abrasive in the stone but is more of a subjective impression of porosity and friability of the binder, which control how fast it wears (usually called "grade" if your talking about grinding wheels)... a stone that wears fast is generally considered to be soft (and generally cuts harder steels faster than a hard stone) while one that hardly wears at all is considered to be hard.

If you're really bored, here is a pdf about grinding wheels http://www.magna-matic.com/pdf/techs...inding_doc.PDF
whetstones would be similar except that we generally don't produce heat, but the grade and structure are applicable to hand stones as they both affect how fast and effeciently a stone grinds a particular steel and the surface finish that is left (and the amount of pressure needed to grind efficiently... usually not a consideration when you're honing a razor on a super fine stone, but a bit more important when you're talking grinding chips out of razors, kitchen knives, lawn mower blades etc.)