Thread: Shaptoneers, please confirm something for me...

To address your issues with the coticule, it's surprising to me that you don't see any difference between edges honed on a coticule with slurry as compared to those without slurry. I notice a difference with no magnification at all. The slurry produces a hazy, dull bevel, and no slurry (just water) makes polished linear scratch lines. Distinctly different with no need to magnify.

And yes, the coticule is said to cut like a 6k to 8k hone with a slurry and like an 8k to 10k hone without slurry. The grit size is not changing, just the speed at which it abrades the steel, which is comparable to stones/hones in lower grit ranges.

Raise a slurry and see how fast it turns black when honing, then try to get the same amount of blackness on the coticule without a slurry. It'll take a lot longer because the slurry is abrading much faster than the plain stone's surface. (don't do this on a good blade, use one in need of a resto or a junker).

Also, the slurry does abrade the cutting edge, which is why it isn't recommended to use the coticule with slurry as a finishing step. It is a "rough cutting" step before polishing with the coticule and water.

Originally Posted by Russel Baldridge

To address your issues with the coticule, it's surprising to me that you don't see any difference between edges honed on a coticule with slurry as compared to those without slurry. I notice a difference with no magnification at all. The slurry produces a hazy, dull bevel, and no slurry (just water) makes polished linear scratch lines. Distinctly different with no need to magnify.

And yes, the coticule is said to cut like a 6k to 8k hone with a slurry and like an 8k to 10k hone without slurry. The grit size is not changing, just the speed at which it abrades the steel, which is comparable to stones/hones in lower grit ranges.

Raise a slurry and see how fast it turns black when honing, then try to get the same amount of blackness on the coticule without a slurry. It'll take a lot longer because the slurry is abrading much faster than the plain stone's surface. (don't do this on a good blade, use one in need of a resto or a junker).

Also, the slurry does abrade the cutting edge, which is why it isn't recommended to use the coticule with slurry as a finishing step. It is a "rough cutting" step before polishing with the coticule and water.

Russel,

For your convenience, I repeated my experiment and took pictures. The razor was a Pearson&co. I hope that will be satisfactory. I picked my vintage coticule to do the laps. In my first experiment, I used one I recently bought from Ardennnes Coticules. But it seemed fair to use another specimen to repeat the experiment, and the vintage one happens to be -by far- the fastest cutter(with slurry) and it does produce practically zero slurry out of its own (it's a hard bugger). I did 100 laps with water, renewing the water every 20 laps, on the entire edge of the razor. Then I put a marker line halfway the edge, taped the heel half of the edge (just to make sure) and did 50 laps with heavy slurry on the tip half of the blade. Then I made a mark at the quarter part of the blade, and did 30 laps on the DMT1200. I cannot see any difference between the coticule parts. Let's suppose there's something wrong with my eyes. Then I placed the razor under the scope and took pictures at 40X magnification. My scope does not have a picture tube, so I shot the pictures through one of the oculars. The pictures are far less quality than what one can see in that microscope. I inspected the entire parts and if I didn't knew which part I was looking at, I sure as hell would not be able to tell the difference between both coticule honed parts. The DMT is obvious enough. I included the pictures. Maybe you can tell the difference. (actually, from the pictures it may look like the coticule with water is -unexpectedly- slightly coarser, but that's just a pure coincidence. If I showed you a whole bunch of pictures from both parts, they would show that kind of variation on either part)

Rating the coticule with slurry 6K to 8K is pure nonsense. There is too much speed variance between coticules to make a grit assumption based on speed, and even then, the question remains what you would be the unity hone, to which all others would be compared. I you rate the grit size of a hone, you need to talk about scratch pattern. The only written source I read about the coticule's scratch pattern mentioned 3 micron and smaller. That supposes to correspond with 8000 grit. Of course the form of the scratches play their part in the game too. So much for comparing grits of different hones.

I love coticules. I hope that being a Belgian entitles me to some affinity with them. And, much unlike what you seem to implying, I don't have "issues" with them. I just like to explore them and come to a better understanding of those hones and of razor's edges in general. They are much more than a "polisher with water". I 've seen a honemeister in Antwerp at work, that uses a coticule in a completely different fashion (Bruno even consideres the guy ignorant to honing because of that), and yet his edges are wicked sharp and lasting. I intend to get to the bottom of all this.

Hi Bart (and everyone else),

I have been in the hospital from the 30th until yesterday so I'm a little late chiming in but I still want to chime. I am going to give you my opinion. Somehow someone may disagree but it's my opinion and I'm sticking with it. Here are my sharpening stones:

I was hoping the last three Shaptons would have been waiting for me when I got home but no, I am still awaiting them. You can see I also have my Belgian stones. I love them, they love me and the love my cutlery:

I have Henkel's Four Star but as I've said, Henkels, Wusthoff, Sabatier, whatever, good cutlery is good cutlery. The tomato is an inconsistant test media as is a human hair so trying to develope a comparative test of sharpness between the two is impractiical. My knives and my razors are all in great shape but not one of them will reliably, repeatably cut one of the very thin, stretchy hairs from my head. Therfore, my hair is useless as a test media. What I usually do is run the blade along my arm with the edge an eighth inch or so above my skin. As a result I usually have random bald spots on my left arm. However, the serrated utility knife (Bottom strip, center knife) will not cut my arm hair but it is the most reliable for slicing a soft tomato. My favorite knife, the santoku (second from the left on the bottom strip) is always shaving sharp but some soft tomatoes will collapse if placed on the cutting board skin side up. I can get them all to cut if the tomato is cut first in half and then I attack the fruit from the freshly cut edge. Okay, here's my theory( and now I expose my soft, newly operated on underbelly for evisceration).

A material is never truly "cut" but rather it is torn at molecular bond lines. Every material has a bond strength that is measurable in pounds per square inch (PSI). The sharpness of a cutting tool employs two separate mechanisms which facilitate that tool's "cutting ability"

1. The finer the edge of a cutting tool, the more readily it will fit between and cleave or separate the molecules of a material.
2. The concentration force applied to the cutting edge of a tool is inversely proportional to the siize of the edge. As the area of a cutting edge approaches zero, the force applied approaches infinity.

I have read that serrated kniife stays sharp because the valley edges (between the points) doesn't touch the cutting board. While there may be some truth to this, I believe the serrated knife will cut a tomato because of the high force concentration at the points will always tear through the tomato skin.

Have I stopped making sense?

Icedog,

Thank you very much for your reply. I like your pictures! I can see you enjoy the virtue of quality tools. Actually the tomato cutting analogy was just a bad attempt to be funny, which is a flaw in my character. But your explanation of it makes sense to me, and the idea of looking at the "peaks" of the edge as spears that concentrate the cutting force in spike points to allow for better penetration is both new and revealing to me. I just finished cutting a tomato in the slowest possible motion, and I could actually see the serrations punching through the tomato skin, before the inclusions follow. The big question is: are similar principles at work when a razor slices hair? At least I can see one flaw in my previous reasoning: I assumed that one hair got trapped in one inclusion between to peaks, and that the sharp bottom of that inclusion did the cutting. How stupid could I be? A hair measures between 30 and 120 microns, while razor striations are about 10 times smaller. Thank you for showing me the light on that. The question of course remains: does "toothiness" really make a difference if applied to a razor's edge? And if so, what would be the ideal size/distribution of the teeth?
I am aware that shapton owners generally do not bother with such ideas, but just put the finest possible edge on a razor and shave while whistling Dixie. As for myself, I'd rather drop dead than slicing tomatoes with a serrated knife, and as far as a razor edge goes, except for the whistling, I have been following the "polish as far as possible" approach. I like to find out IF a "striated" approach to razor's edges makes equal, less or more sense.

Thanks again for chiming in.
I hope you make quick and full recovery,

Bart.

Originally Posted by Bart

Rating the coticule with slurry 6K to 8K is pure nonsense.

First off: I haven't intended to offend you, I just wanted to share a differing experience.

Second: When I said "issues" I was making reference to your own claim that you find the coticule's behavior "enigmatic", nothing more.

And, I think you're misunderstanding what I meant about the abrasive action of the stone. I don't intend to actually rate the grit at any level other than what it is, what I mean is that the extra garnet content in the slurry cuts steel with a speed that is much faster than the usual "8k"coticule. So it is as if the coticule were a 6k when you form a slurry, not that the garnet cuts 6k sized scratches. And, in fact, this is the case when you raise a slurry on many abrasive stones, not unique to the coticule.

Your experiment is nice, it was thoughtful and well executed. But it is faulted by the previous misunderstanding, in that the grit size has stayed the same, so yes, they look very similar. What your pictures don't show is the amount of material each method took off of the edge, which is what I meant by the lower/higher grit ratings. If you get an old wedge or some other razor with a fat bevel I think you'll be able to see what I mean by the "hazy" look made by the slurry, and the "polished" look made by the plain wetted (I've heard the word somewhere, so I'm gonna run with it) surface.

As for the wide variance in performance characteristics among natural stones; I am well aware of it, to say the least. But it is much harder to describe to someone (usually new guys looking for "the best stone for the money that will do everything I need"), with no first hand knowledge of the subject, how the slurry cuts faster but is the same grit as the base stone, or how the stone can both set a bevel and give a fine polished edge. It's just easier to make an analogy to lower/higher grit ranges.

And sure there is documentation saying that garnet is a crystal that is an X rating on the MOHS scale, it is, on average, Y microns in diameter, with Z number of facets, and that the Coticule is comprised of between ALPHA and BETA percentages in concentration of garnet crystals. But unless you get your precise stone analyzed, your still just guessing at it's rating anyway. And when it comes down to being realistic, you just have to have a bunch of stones to compare performance characteristics and decide what kind of rating fits.

(Does anyone remember what happened to that project where there was a chart that compared the different characteristics of various stone to the Nortons and DMT's?)

Originally Posted by Russel Baldridge

First off: I haven't intended to offend you, I just wanted to share a differing experience.

It is true that I felt a bit patronized by your reply. But I have a great appreciation for your knowledge about all things steel and sharp and your willingness to share with others. I think we have that in common, at least the willingness to share part.

My statement that rating the Coticule with slurry as 6000 grit is nonsense, was not directed to you. After all, you only mentioned others rating it that way. A coticule with slurry cuts at least 10X faster than one wiith water, and both you and I are not going to start rating it 600 grit, are we?

Thanks for thinking this thing through with me,
We have been quibbling before. I don't take that personal, and I hope neither do you.

Kind regards,
Bart.

Nope, no personal offense taken.

As for the striations; I think that, at the lower grit levels, the uneven portions of the edge that feel like teeth may be comparable in sharpness to the final desired shaving edge so they are what's making the blade appear to pass the HHT but in reality, the main cutting bevel is much too dull (not to mention that you'd have some serious razor burn from the teeth) to shave with. And when higher grit stones are used to remove the inconsistencies along the main cutting bevel, the sharp teeth are removed, leaving a slightly duller, but much smoother, razor edge.

This can be continued up as far as one wants to, or can realistically, go (i.e. shapton 30k, Nakayama, .25 diamond). And at some point, the edge just cannot get any finer. I have yet to tell a difference between CrO and my Nakayama because, at those grit levels, the striations are almost non-existent and it's the quality of the steel and the bevel angle that are the noticeable properties.

So, to summarize my attempt to answer your question, I am saying it's possible that the teeth are sharper than the main bevel, sharp enough to pass the HHT, and that a polished razor edge returns to the same (or finer) sharpness of the original teeth but without the serration. Thus making the edge "shave ready".

Is that somewhat in line with your observations?

Russel,

What you describe is what I believe to be the foundation of "the progressive honing method". From the very beginning it always made the most physical sense to me, so I have learned to hone my razors by those rules and still am to this day. My edges shave well and last between 10 and 20 shaves before I need to touch up. Many people would be happy with that and never give the bare physics of honing another tought. But that's not me...

There's the pyramids. No doubt in my mind they result in fine shaveready edges, but I can't honestly believe that 5 laps at 8K can remove 1 lap of scratches at 4K. I could be wrong, having no experience with Nortons and all. The last thing I want is this thread gliding off to yet another "progressive" versus "pyramid" discussion, so I 'm not going to say anything more about that.

But I have another observation: Robert Chevalier, owner of a razor store in Antwerp, tutors shaving and honing classes. As I mentioned in previous posts, his method really works, and because of the success of his courses, there are probably more people in Belgium that hone with Chevalier's paradigm than those who follow one of the methods advocated on SRP. Chevalier does this:
He raises a good slurry on a coticule. Then he hones, usually without X-stroke, a number of laps on the coticule, till the TNT passes. Next he runs the razor over a piece of horn that he keeps in water. It smells awful, and I really think it is not needed, but he states they do the same at Dovo, and it serves to remove a possible burr. As a final honing step, he does a few very light laps on a pasted paddle strop, cured with red Dovo paste (that's 4 (edit) micron!, if I'm not mistaken). He doesn't do much, just enough till the razor passes the HHT. (Is he pulling some teeth out of that finely polished coticule edge??) Then he strops about 20 on canvas and a bit more on clean leather. That's it.

I saw him do it. I saw his wife do it. I have tested a razor honed by her, that I knew for sure to be dull prior to the honing (a heirloom piece that had been lying in a drawer for 30 years). It passed the HHT very well. My friend learned to shave with that razor, and it stayed keen for many shaves.

All that leads me to wonder if there might be two types of edges. The one I have on my razors as we speak, which corresponds with what you describe in your mail, and another type of edge that includes "teeth".
The first thing I need to know to answer that question, is whether "teeth" really makes a difference for cutting a hair, hence the Shapton experiment I called for. I really hope there are people willing to perform the experiment (polishing an edge with a progression of Shapton hones and performing the HHT after each hone), and start posting their results any time soon.

Bart.

Coticule rated as a 6000? What's THAT about? I've been honing razors for years on coticules and have customers around the world who have been doing so as well. Their consensus is the coticule (Select grade) is rated as an 8k but polishes an edge to about a 10k. The belgian blue is similar. It is rated as a 4k but polishes toa 6k. You do have to use a slurry as the Belgians (and I) recommend. A pure coticule slurry stone ("cotigura"), a word I invented, is the best slurry stone to use either with coticules or belgian blues.

Hey Howard,

Nice info, thanks for contributing. Yes I saw Zowada's photos. I tried dry honing, but did not liked the results as much.
Another thing I have been trying, is to backhone on slurry after setting the bevel on a DMT, and then finish with a normal stroke on water. The results were very good, but I 'd have to build more experience with that approach and compare it to my regular honing paradigm, before I could confirm if there's any real advantage.