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Question over at SRP

Tok

Well-Known Member
It´s here:

http://straightrazorplace.com/hones/70108-coticule-slurry-bs.html

Besides the "Coticule Crew" bashing (or whatever…), what do you think?

Regards,
Tok
 
G

Guest

If you apply a filter to eliminate one particularly obtuse but vocal member, that is an interesting, and overall well balanced thread. If you want to enhance it, I suggest you do it over there.

Regards,
Robin
 

torbenbp

Well-Known Member
Quite interresting...Perhaps they might even be right. A quick google search revealed no coticule garnets captured by SEM. Darn,the Ardennes Coticule played us all a trick!
:w00t: :w00t: I suspect this is just the first step, as the end target is world domination...


Excuse me,I have to go and dig a shelter..

Torbs
 

rtedwards

Active Member
That is quite an interesting thread. It would be nice if we could discuss the information available here to avoid the negativity of some of the posters, but in any event there are some clear heads weighing in and it is worth following. Whether I fully understand the mechanisms underlying the coticule's honing properties is different than learning to use the stones to hone. But it is interesting to know why they behave as they do. Not being one to need magic to feel wonder I always like to have a mechanistic explanation if one is available.
 

Jeltz

Active Member
Well I don't really care whether its garnets or not all I care about is that it works.

I started a thread on Shaveready the other day based on the concept that Coticules must be made from compacted fairy dust given how mine magically transforms my poor honing skills on other stones to competent ones which let me produce nice smooth sharp edges.
 
G

Guest

And that is exactly the sort of sciolism that makes Coticule cultists and certain shaving related forums alike a bad name.
 

TM280

Well-Known Member
Well, on the suggestion that there was something worth reading, I read that thread. With my manual filter engaged, so if I missed a piece of vital clarification, forgive me.

Perhaps I am missing the point of the original question, but I don't see anything to be answered. There are some good links provided to pictures of garnets, always interesting, but "are there garnets released in coticule slurry"? If anyone is actually in doubt, they would also have to doubt there exists garnets in coticules. Perhaps they do...

Any substance in a rock will be found in the ground away portion. Physically altered? Perhaps. What was the question again?

regards,
Torolf
 

rayman

Well-Known Member
I haven't looked at the article, but it wouldn't surprise me if they ran the test on the BBW side of a stone and didn't know it was actually slate. After seeing their presentation of a one stone honing, I am convinced that the members are just followers, hell - even Lex Luthor's assistant could have seen that they honed the razor first on synthetics before using the Coticule.
 

Bart

Well-Known Member
The thread was pointed out to me a couple days ago. I read it then.
So, without bothering to catch up with it, here are some facts:

Coticule rock has, for various reasons, piqued the interest of geologist and mineralogist, and has been extensively submit to scientific research. Scientific papers have been submitted and approved for publication.
Some of them are available online in digitized format, albeit not all for free:
Alphonse Renard, "Sur la structure et la composition minéralogique du coticule et sur ses rapports avec le phyllade oligistifère", 1878 is one of the earliest studies known to me. It's in French. He describes in detail how the garnets look as examined with various microscopic techniques (polarized light, etc) under magnification of 600 to 800 X.
It was also Renard who coined the term "Coticule" in its scientific meaning:
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See:
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This link contains a study of a Coticule deposit in The Bahia Mansa Complex, CHILE. It contains some interesting pictures of garnets, as found in Coticules.

Another well-known paper is: "The Coticule Rocks (Spessartine Quartzites)of the Venn-Stavelot Massif,Ardennes, a Volcanoclastic Metasediment?", By Ulrich Kramm, published at Mineralogisch-Petrographisches Institut der Universitât Köln, Germany.
Also Kramm describes garnets, their sizes and composition. The paper is available through Springerlink:
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It is not a free resource, but I have a copy:
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There also exists a recent book about the topic of Coticules, written in French under the scientific direction of Dr Sc Eric Goemaere, geologist at the Geological Survey of Belgium - Royal Belgian Institute of Natural Sciences.
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The book shows a very clear picture of a garnet as shown by a scanning electron microscope. It also elaborates about the composition of Coticules in detail. Another picture shows a large bunch of garnets as seen through a polarizing microscope. They are all smaller than 10 micron. There are the drawings Alphonse Renard made based on what he saw during his microscopic examinations: round and rhomboid shaped particles.

Apart from that, I don't care if they work with garnets or petrified droppings of a dinosaur.
I do regret the infantile innuendo towards the honesty of Ardennes Coticule about the product they sell.

Kind regards,
Bart.
 

Loric

Active Member
Bart thanks for all the articles! Its amazing that you put more facts into a couple paragraphs than they did in pages of "debate". At worst I'm thank full that some real scientific insights are being brought out.

So does anyone know if the Bahia Mansa Complex Coticules are useable to hone on?
 

Bart

Well-Known Member
Loric said:
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It is doubtful. As explained the scientific use of the word Coticule comprises all rocks consisting mainly of quartz and spessartine-rich garnet. Not only need the garnets to be a sufficiently small granularity (which is obviously the case in Belgian Coticules), but also the quartz must be very finely grained. Fine enough to have either no real significance in the abrasion process, or either to have no detrimental effect on the result of the garnet based part of the abrasion.

In the paper about the Bahia Mansa Coticules report quartz particles with grain size up to 800 micron. That would surely harm the edge of a razor.
As explained, there first was these Belgian rock with commercial use as whetstone, called Coticule. Only later the term, in its geological meaning, was expanded to other rocks containing spessartine garnets, but not necessarily with the same abrasive properties as the Belgian rock.

Kind regards,
Bart.
 

Loric

Active Member
Thank you very much Bart! Thats quite interesting.

800 micron :scared: That must be in the ballpark of negative 500 grit.
 

altshaver

Well-Known Member
Bart, if there are any other journal articles you know of, but do no have access to, let me know. I am a graduate student, and I have access to many scientific journals. I'll take a look if I have time as well.
 

håkan

Active Member
I only made it to page 3 of that thread.
That's where someone referred to "Utopian" as; "being an actual science guy"...:thumbdown:

Almost every "scientific" discussion Ive seen on shaving forums have been firmly stuck in some kind of kindergarten-style Newtonian mechanics and a lot of people get simultaneously impressed and intimidated by that.

I blame the educational systems and capitalism. If it's not immediately profitable, noones allowed to spend time on it.
 

håkan

Active Member
Heh...

It's actually quite funny that you interpreted my statement as criticism towards your precious empire...

Capitalism were neither invented nor perfected in the USofA and even though you "did well" during the reaganomics-era youre hardly leading the capitalist charge although you, as a nation, are it's "poster-boy"
 

Jim1

Member
I think I interpreted it that way because the individual to whom you were referring was an Iowan, a state near and dear to my heart.;) I do see you point now, though. And I also agree that we are not leading the capitalist charge. We'll get around to changing that soon!
 

Bart

Well-Known Member
Let's not turn this into a debate over economical politics, or inhabitants of Iowa, shall we?

Now that we've documented that Coticules indeed do contain spessartine garnets, let's present some important facts about their nature:

Spessartine is a member of the garnet group, more in particular of the garnets that contain Aluminum as the second element. (there are is a garnet group based on Calcium). The chemical formula for spessartine is Mn(II)3Al2(SiO4)3.
The hardness is above 7 on the Mohs scale. This means it's hard enough to scratch (or abrade) steel.

The shape of spessartine garnets is mostly
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. They do not show cleavage, which means that they don't break down in separate fragments. If you want to crush a garnet, you'd have to crush it with a strike. This doesn't happen with the forces applied during honing, hence it is fair to say that the garnets will be found in their intact state in a Coticule slurry. They will however wear, and loose their well defined edges, during use.

While honing, the garnets not only abrade the steel of the blade, but also the surface of the hone. The other minerals that holds the garnets bonded into the stone are more easily to abrade than steel. As a result, once a slurry is present, a constant flow of fresh garnets is released into the slurry. It is a combination of garnet size, shape, concentration and binding properties of the surrounding minerals, that define the abrasive speed of a Coticule.

It is not difficult to understand that with the garnets still partially embedded in the surface of the hone, the Coticule will slow down considerably and the penetration into the steel will be far more limited than with the garnets fully exposed and present in more abundant quantity. This effect can be observed by anyone who owns a Coticule. With slurry, the Coticule will remove material much faster: this can be witnessed by the discoloration of the slurry, but it can also easily be heard (the abrasive sound is noticeably louder) and felt in the fingers that hold the razor. Also the microscopic view of the abraded surface looks different, often referred to as "the sand blasted appearance". With water, the Coticule will be quieter, the feel more glassy, and the surface finish will gain a more polished look.

Kind regards,
Bart.
 
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