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the coticule is reportedly a finishing stone to be used after the norton 8k. When i use mine and look at the bevel, it apears as though the scratch patter after the coticule is much courser than after the 8k norton. I tried the coticule again last night after working up a slight slurry on it. I was horribly dissapointed in the results and went back to the norton 4k to start over again. Has anyone ever encountered coticles that act courser than the 8k?
I have encountered a wide variation in the quality of newer quarried Coticules, hence my reasons for not selling them any longer. I still offer vintage stones when I can get them but have given up finding a consistant supply of newer yellow coticules.
Tony
The fact is geologically speaking the coticule is a type of stone with embedded crystals which do the cutting. depending on where the stone originates and even the part of the same quarry it is mined from there can be great variations resulting in you getting a poor result when you use it to hone.
Unless each stone is sampled under magnification you really won't be able to tell whether its a fine or coarse stone. Think of the term coticule like diamond. There are very fine flawless diamonds that are worth 25 grand a carat and stones worthy of industrial use but they are still diamonds so all coticules are not created equal. You really need to know your seller or know exactly from what quarry they came from and have some knowledge about the petrology of that quarry.
Sometimes even a visual inspection will not tell you what a stone will do. I se mainly two types. Those with visable "grain" or crystaline structure and those of a smooth, homogenous nature. I sent a fairly coarse looking one to Lynn and he semed to have very pleasing results with it while a very smooth looking stone I had sent out was very coarse cutting. My customer was not pleased and I immediately took it back and sent it to another member for testing who got similar results. So, back to the quarry it went!
Tony
I have read of more problems with coticules on this forum.
That's why I have decided to visit the quarry in October during the autumn holidays. According to others who visited the place the owner is quite knowledgable about the various aspects of coticules. His quarry's got about 20 veins, all of 'em with slightly different stones. If anyone's got any questions etc. let me know: I'll ask & report back.
If buying a new coticule you may want to ask your dealer on availability of "Kosher Quality" stones. The Belgian is favored by Kosher butchers and they will buy only the best grades of stones. I had a few Rabbi customers and they were very knowledgable as to what made a good Belgian coticule.
Expect to pay a premium for ones like that though. I was always quoted a 30% premium.
Tony
You bet Tony and another premium for larger sizes, ie 8x3 or 9x2.
Lynn
Lynn,
Those large ones are indeed rare. I just returned a defective 2 1/2" x 12" to Belgium but my prize is a 2 1/2" x 10" natural blue/yellow. This and a smaller natural will cover anything I ever need.
Tony
Maurice Celis of Ardennes Coticules e-mailed me that the 8"x3", optically flawless coticules sold in the USA have a lower garnet content. Reason: those stones can only be extracted from a small number of veins with a lower garnet content.
According to Mr. Celis this makes the stones slower cutters.
Would that be the cause of disappointing perfomance of some of the stones?
Kees,
The stones I got from Maurice that were returned were because of cutting too coarsely. These looked fine grained but gave an edge similar to a 4K Norton. These were not "Kosher Grade" but the regular supply from Ardennes.
Tony