Unusuable BBW?

[mrmaroon]

I bought a vintage extra choice selected grade coticule off ebay. The coticule layer is the most perfect specimen I have ever seen. There are no lines or patterning at all. I would guess it is a petite blanche or a veinette.

The main point of this post is the BBW layer it is glued to. I tested it with a razor and the razor got caught by a bump on the surface. It took out a nice chip in the edge. The whole surface is rough like that. It looks like a normal BBW unless you look at it flat, if you do you can see a raised surface.

Is this BBW not fit for razor service? It works well on my knives. Even the slurry has some of the bumps in it. I will try to post some pictures soon.

MrMaroon

 

[Paul]

All the La Petite Blanche and La Veinette specimens that I've seen have some sort of manganese inclusions, and they are naturally combos because the layers are so thin that they typically can't be cut into multiple stones. If it is either of those layers, it would seem to be a bit of an odd duck... Either way, it will have to be one of the odd ones that separated from the natural BBW backing...

While it's possible that it is a BBW that's unfit, I wonder how it would work if you lap it a bit further. With the amount of superlatives used to describe it ("extra choice select"), I would have had to pass on it, though :

 

[mrmaroon]

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It's a mouthful I know! I should have added pikes!

I doubt lapping it will prove any better, because the bumps can be felt on the side of the BBW all the way to the glue line. It isn't a natural combo. They aren't little bumps either, they catch the edge of the razor and stop it instantly. It is a weird feeling. I will take some pictures, but it looks much like a normal BBW, except the red "garnets" are larger and stick iup just a tad.

 

[Bart]

It's probaly some hard inclussion in the rock. In the old days, as today, the glued backing of a Coticule was never intended to be used as sharpening stone. Its function is to reinforce the Coticule. They used Blue stone, because that's what they had available in massive quantities anyway. Labor was cheap. Having employees sawing and lapping blue stones was the economic logical thing to do. Nowadays, labor is expensive. Vietnamese slate flooring tiles are much cheaper than having a Belgian laborer turn local blue rock into backing plates.

But the idea was the same. Not all blue rock is suitable for honing. In fact, there's only one blue vain that has ever been exploited as sharpening stone. That was one particular layer at the Ol'Preu deposit, known as La Veine Lorraine, aka "Salmon Rouge". It's a purplish BBW. But recent research at the university of Liège revealed that also other BBW layers at the Ol'preu deposit have some garnet content and can be used for honing. It also appears that blue stone situated adjacent to Coticule rock - in other words: the blue rock naturally joined to combo stones -, has sufficient abrasive properties to serve as a sharpening stone, although there are differences in speed between various specimen. Obviously, the blue backing of your vintage Coticule, has not been naturally adjacent to Coticule, otherwise it would have been a natural combo. We also don't know whether this stone comes from Ol' Preu. Likely not, because there were so many other mining locations that the odds are low.
While we're at it: in my opinion, you are far too quick to call a particular stone "La Petite Blanche" or "La Veinette" (there was another thread a while ago, but unfortunately I didn't find the time to address this issue then). Without knowing the exact mining location, is it nearly impossible to determine a layer. There were layers that are currently not being accessed by the last remaining mine. "L'allemande", comes to mind, but also "Les Petas", "Les Dados"; just to name a few. We don't even know if a Petite Blanche from Tier Du Mont, or from Old Rock, or from Regné, Hébronval or Ottré,which were all important mining spots, display the same morphological appearance as the ones we know from Ol'Preu.

But of course, all this information must never withhold you from enjoying that Coticule.
Sounds though, like to blue part won't be of much use, this time.

Kind regards,
Bart.

 

[mrmaroon]

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If it is the old rock you are referring to, it was ralphy that said it originally (no offence to him). After testing that one I have high doubts it could be that layer. Superficially it does look very close though.

This one still needs further testing, however it does look and preform like the other two veinettes I have tested. For some reason though I am getting better dilocot results on it than I usually get with that layer. It could be I have learned quite a bit more since then. It could also be that it isn't anything close to that:w00t: ! Probably both: .

My limit before stropping keeps getting set higher and higher as I keep getting better and better. My third try on this one I got HHT-3 off the hone. I usually have to work very hard to accomplish that on any of my others with my medium hair thickness. It is still awaiting a shave test.:sleep:

Also Bart, I remember you mentioning that you had a coticule with "spikes" in it that you had to send back to ardenness? I wonder if my results are similar to yours?

Regards,
MrMaroon

 

[Bart]

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n°27 in the Vault (repository1). The pink dots were ok, but the orange one caused havoc.
[img=800]http://www.coticule.be/tl_files/Coticule%20Vault/Coticule027.jpg[/img]

Kind regards,
Bart.

 

[Woodash]

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The coticule does look like a bit of an odd duck based on my limited experience - but an interesting one. I'd be curious about the abundance of the white material in there and the orange color may be from another type of garnet present. How does it work?

 

[Bart]

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According to my unpublished notes, it was slow on slurry, with +++ for sharpness. There were orange specks sparsely present on the surface, among the large amount of pink/red specks. Those orange specks caused small chips at the very edge. They were large enough to be seen with the naked eye (albeit barely). Too bad, because it's a beautiful stone.

Kind regards,
Bart.