Thread: Coticule edges (dilucot) under microscope 160x

Originally Posted by Euclid440

I too have suspected that the rough surface from a diamond plate stone can impact the stones ability to polish.

In Grinding and Honing part 4 Bos warns against lapping with diamond because he says the sharper / harder diamonds shred the garnets in the coticule making them less effective for polishing. That would support what you say. Since reading that I have stuck to Silicon Carbide for lapping. I have also started pairing similar sized / types of coticules and rubbing them together after honing until the suction ceases. So far this seems to be quite effective for keeping them flat.

Originally Posted by Seveneighth

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I have also started pairing similar sized / types of coticules and rubbing them together after honing until the suction ceases. So far this seems to be quite effective for keeping them flat.

Good Idea! I think it works best if you have 3 stones rubbing their surface to to each other.
Having only 2 stones in your "lapping team" you might run into a problem that one stone develops a kind of "hill" in its surface and other the "tale" matching to the hill of the first one.

Philipp

Originally Posted by Philipp78

Good Idea! I think it works best if you have 3 stones rubbing their surface to to each other.
Having only 2 stones in your "lapping team" you might run into a problem that one stone develops a kind of "hill" in its surface and other the "tale" matching to the hill of the first one.

Philipp

That's a really good point. I hadn't thought of that. I have enough stones of similar sizes to do that. - Thanks!!

Great photos by the way! - I am still trying to digest them. So many questions...

I like the way that the initial bevel from the nakayama kiita contrasts with the second coticule bevel. The coticule scratch pattern shows up nicely. I would be curious to understand the interplay between the scratches from the first bevel and the second when the unicot is performed on a single coticule. I still can't get my head around why, with certain stones, the unicot edge I get is so much sharper than a dilucot with the same stone.

Bart covers it in his original post:
https://sharprazorpalace.com/advance...le-honing.html

But it would be nice to be able to visualise what is happening to the metal. My guess is that the scratch pattern on the second bevel would intersect with the scratch on the original and even out the edge. Much like two hatching patterns on the shading of a drawing coming together to form a hard edge.

Just to chime in old coticules were never sold with a slurry stone. I haven't seen any ever sold in a box with a smaller stone or instructions asking us to use slurry on a Belgian hone.

Has anyone else?
I have seen instructions to use water or oil or lather. And I don't buy the idea that lather meant slurry, there's no evidence of that.

Originally Posted by Seveneighth

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I still can't get my head around why, with certain stones, the unicot edge I get is so much sharper than a dilucot with the same stone.
...

I think that the slurry-dulling is playing a significant role here.
Coming from slurry stage in dilucot the edge needs to overcome the damage produced by the slurry at the very apex. Meaning during the dilution stage still certain metal needs to be removed.
But also in the dilution stage the slurry applies some dulling action on the edge.
So it could be tricky to refine the edge as long a any amount of slurry is present.

Now on water only Coticule might be too slow to remove the damage of the slurry at the very apex in a reasonable time.

Putting a tape to the spine significantly decreases the surface of contact to the stone. This boosts the refinement power of the same stone. Working that way allows to achieve the desired refinement with acceptable effort.

I am sure careful dilution and more work on water in dilucot can results in the same keenness of the edge as with unicot method. Haven’t achieved it my self yet...

"I too have suspected that the rough surface from a diamond plate stone can impact the stones ability to polish."

"In Grinding and Honing part 4 Bos warns against lapping with diamond because he says the sharper / harder diamonds shred the garnets in the coticule making them less effective for polishing. That would support what you say. Since reading that I have stuck to Silicon Carbide for lapping."

Two different things and not something we see, diamonds imbedded in a stone. A single 300 grit would be painfully obvious in a 6-8k grit stone.

Diamond plate are easier and faster, if you refresh often and you should.

For polishing, where you are only doing a limited amount of laps the smoother stone surface will polish better. For general honing the rough surface will wear smooth after multiple laps.

Originally Posted by Disburden

Just to chime in old coticules were never sold with a slurry stone. I haven't seen any ever sold in a box with a smaller stone or instructions asking us to use slurry on a Belgian hone.

Has anyone else?
I have seen instructions to use water or oil or lather. And I don't buy the idea that lather meant slurry, there's no evidence of that.

Me neither, I've gone away from using them with slurry anyway

Philipp

Excellent thread and most excellent photos. How about a photo of your microscope?
Early on you said that you used a Jnat to refresh the bevel before using the Coticule, and that you did not use a diamond plate to make a slurry. I do not wish to misrepresent you so please correct me if I am wrong.

I have found that most any Jnat will contribute some slurry during a honing session, some more than others, and I have found that any slurry from a jnat or a coticule or on an arkansas will by adding that cushion of free roaming grit, will be prone to convexing the bevels of a razor. These less than flat bevels stipulate that when you next lay the razor on a flat surface the edge will be proud above the flat surface, in our case the next slurry-less stone. For this reason I suggest that you use a synthetic stone, one that does not self slurry to create your model bevels for you studies. A good hard synthetic, where the grit remains bound up in the stones matrix will give you flatter, truer and dependable model bevel for which to build your Coticule edge upon. This is evident from your "taped spine" photos where the edge seems to be more greatly affected right at the Edge. Any slurry can by its very nature change the geometry of a bevel, for you photos studies it is helpful to begin with a "V" shaped geometry rather than a "U" shaped or rounded bevels geometry. Having the V shape will give you more proof positive reading and photos.

About using a diamond plate on a Coticule, I agree that the diamonds can rip the garnets or shred them as suggested. Garnets are not friable if they are born in a soft binder matrix. If the garnets were of a mass of solid garnet all bound together a diamond plate would cleave them, but when they are bound in softer clay like matrix, they just come loose as whole/sized granets and abrade your razor with their rolling around as full size grit particles. The relatively softer matrix of a Coticule will disgorge the garnets before they would have a chance to cleave from a diamond. The Atoma or DMT will really only work or work especially well with Jnats because these naturals have a homogeneous stone matrix and friable silica grit particles. The silica and clay might break off in larger clumps from a diamond plate, but the water soluble clay matrix quickly releases these bundles packing and the silica is free to cleave as individual particles.

Back to the tape. I suggest that for your photos that you begin each session with a perfectly flat bevel made with an efficient synthetic that does not slurry and the go directly with out alteration to your Coticule, without an intermediate stone or abrasive before the Coticule. I like to, when doing this, create diagonal scratches with the synthetic and then with the Coticule as an example use only straight edge leading strokes. This gives good contrast and accounting as to the amount of steel that is being abraded by the Coticule at the edge. This is the approach I tried in this video. Again, your photos are great and I am sure authentic.

Alex

Great pictures Philipp! You have a nice set up to get clear pictures.

Research science teaches you to take away as many variables you can so your peers can replicate the findings you are reporting on. Alex idea of jumping off a known synthetic is much more repeatable because you can go out and by that synthetic and colabrate or point out any variables you missed. A Nakayama is great but you can't go out and buy a Nakayama that has the same properties as yours(hardness, grit level,etc.) So a synthetic would be great in this application.

Playing in the mud is very effective and rewarding when you figure it out. Alex videos and personal help, helped to speed up my learnong curve and taught me to understand the influences that can happen and the effect they have on the edges.