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The better coticule has no surface flaws

chris

Member
The black markings on the surface of many coticules make them unique and create an image which I find quite attractive. I've spend some time just gazing at the patterns one can see on stones such as #7 (what a beauty!),33, 34, 35, and there are many more of them (the soft lines on #10!).

Then I started wondering about the specifics of those black dots or lines or stars. I have no clue what it is and if/how these affect the behaviour of the stone.

Is it the slate that shows through, or is it another material? Are they considered to be fault lines and do they affect the honing behaviour of the stone (and how)? Can I compare them with scratches or dust or even 'craters' on a telescope mirror? Those scars on the mirror are 'only' cosmetic flaws, the human eye cannot discern any deterioration in the image the mirror produces unless it's extreme. Only one's pride gets hurt :mad: getting a scratch (or worse :scared: )on the mirror surface. It will cause no difference in the perception of the image. So it is considered good practice to leave the scars, dust etc. in peace, one should not even try to think about them.

So my guess is that these markings on the coticule surface are indeed fault lines and that theoretically they should be regarded as less excellent compared to the white stuff :blush: (this is more a question, it is not really a statement).

Or is it also here safe to state that their effect on the blade can/should be ignored. Better to observe the beauty of the thing, the result will be ok? :blink:
 

Smythe

Well-Known Member
As far as I know, the material in those lines has no “negative” effect on the edge of the blade honed. It’s only human nature to prefer the visually “pure” and “unblemished”.
In fact, if you read some of the posts of those who have one, they are getting excellent edges. And I intend to get one of those “polka dot” ones from this lot before they are all gone).
 

tat2Ralfy

Well-Known Member
chris said:
Is it the slate that shows through, or is it another material?

It is another material, naturally formed as the coticule layer "grew", it would impossible for the slate backing to show through, esp in the case of #10 as it is a natural combination stone and contains no slate what so ever, further if there was slate present on the honing surface it would render the hone unusable, very very rarely Ardennes produces stones that contain "inclusions" that make them unsuitable for honing.

chris said:
So my guess is that these markings on the coticule surface are indeed fault lines and that theoretically they should be regarded as less excellent compared to the white stuff :blush: (this is more a question, it is not really a statement)

No there are not fault lines unless they effect the honing capability of the stone as above.

chris said:
Or is it also here safe to state that their effect on the blade can/should be ignored. Better to observe the beauty of the thing, the result will be ok? :blink:

Bang on! remember these stones are naturally formed over about 480 million years, any markings are purely cosmetic and perfectly natural, if the stone is produced by people who know what they are doing as in Ardennes, the performance will be affected in no way, the wonderful soft lines in my beloved # 10 cannot be felt, they effect the hones performance not one bit.

Hope this helps :thumbup:

Ralfson (Dr)
 

Paul

Well-Known Member
This reminds me of the discussion about the Kosher Coticules. Very interesting, indeed :)
 

Bart

Well-Known Member
Black lines and dots in a Coticule are almost always deposits of Manganese dioxide (Mn0²)also known as Pyrolusite.
The crystals have a hardness of 2-5 on the Mohs scale. That's too low to have much effect on hardened steel. Besides that, the crystals cleave very easily (Pyrolusite is extremely brittle), and quickly crumble to a fineness way below any significance for honing.

Manganese plays a key role in the formation of spessartine garnet crystals, which is the abrasive medium in Coticules. In abundant presence of manganese during the formation, some 480 million years ago, these black ores of Manganese leftover signify that a particular Coticule is densely packed with fine garnets. These stones nearly invariably turn out to be fast and fine cutters. In that sense a few traces of black are a sign of excellent quality, rather than to be considered a flaw. If I were to decide pricing politics at Ardennes Coticule (which luckily I am not), you guys would hate me, because I would raise the price on all stones with black ores. :p

Best regards,
Bart.
 

Paul

Well-Known Member
Bart said:
Black lines and dots in a Coticule are almost always deposits of Manganese dioxide (Mn0²)also known as Pyrolusite.
The crystals have a hardness of 2-5 on the Mohs scale. That's too low to have much effect on hardened steel. Besides that, the crystals cleave very easily (Pyrolusite is extremely brittle), and quickly crumble to a fineness way below any significance for honing.

Manganese plays a key role in the formation of spessartine garnet crystals, which is the abrasive medium in Coticules. In abundant presence of manganese during the formation, some 480 million years ago, these black ores of Manganese leftover signify that a particular Coticule is densely packed with fine garnets. These stones nearly invariably turn out to be fast and fine cutters. In that sense a few traces of black are a sign of excellent quality, rather than to be considered a flaw. If I were to decide pricing politics at Ardennes Coticule (which luckily I am not), you guys would hate me, because I would raise the price on all stones with black ores. :p

Best regards,
Bart.

It's bad juju just throwing that idea out in the universe :scared:
:p
 

tat2Ralfy

Well-Known Member
Note how the "3 Sisters" L#1,2,and3 are soo creamy with no distinct black "Birthmarks" yet they cut faster than an iguana drinking! :thumbup:
 

Bart

Well-Known Member
tat2Ralfy said:
Note how the "3 Sisters" L#1,2,and3 are soo creamy with no distinct black "Birthmarks" yet they cut faster than an iguana drinking! :thumbup:
Indeed. But which one did Bartman the Avenger keep all to himself?:D
 

Bart

Well-Known Member
Those lines actually remind me of bubble chamber pictures that reveal the trajectory of quarks and other elementary particles.
I think the resemblance is striking.:)



And the real stuff:
 

chris

Member
Hi there,

Thanks for the reactions so far, it is enlightening, although I still have questions about all components in our coticule. I am planning to give more details of what is going on in the coticule (happens to be another hobby of mine)and during the weekend in Belgium I planned to study a promising chapter in that book (French written) published by the Geological Survey. I read the chapter and I guess it may be of interest to more people too.
So far I go with Bart who explained it as
almost always deposits of Manganese dioxide (Mn0²)also known as Pyrolusite.
although I'm not completely convinced of the Pyrolusite as that mineral has some special characteristics. So I need to study more :blush: hope you forgive me for being stubborn, but I am interested in those quark lines and dots :)

A reason that I do not write more now is that I also visited Antwerp last Saturday and treated myself with my first ever straight razor (Dovo with a silver steel blade they call it I guess). It looks wonderful, but before this morning I didn't dare to touch it, again, I also need to study how to confront my skin with this type of steel, and I have a lot of respect for all of you who use it already on a daily basis ;) Also the accessories seem to be worth of careful study. I know, I shouldn't study too much, "just do it" and there will be other kind advice, but still, ... it's really sharp. I shaved my right cheek, only trouble I had was with the mirror which seems to be too small to get a good view of what is happening :lol: , so I just went for it "by feel". Not a bad trial I guess, I still could smile afterwards while finishing off with my old "Gilette-style" razor.

And about the Coticule, well, I certainly want to find out the details :) Regards, and enjoy the next shave!
 

Bart

Well-Known Member
The matrix that bonds the garnets in Coticules, is composed of a whole list of phylosilicates, all listed in that excellent book you're referring to. Difference in composition of that matrix is surely responsible for at least part of the differences we find in Coticules. Yet there's little doubt that the black lines are of a manganese nature, and do not have any direct significance for the honing properties. But if you can't take my word for it, have fun finding it out yourself.:thumbup:

Good luck with your recent straight razor purchase. The koordenwinkel in Antwerp is one of the nicest stores to by traditional shaving gear in Belgium. I too bought my first straight razor there. It's been a passionate journey ever since.:)

Best regards,
Bart.
 
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