Thread: Advice on purchasing a coticule

dinnermint makes an excellent point that I too have followed.

I NEVER use a diamond plate for raising slurry on a coticule, only another piece of coticule as a slurry stone. Why? Coticules are made from larger garnet crystals (think glass) and sharp shards of diamond will easily fragment those garnets, leaving sharp pieces in the slurry or sticking out of the substrate. Gently using a cotigura (small coticule hone meant for raising a slurry) will be more likely to release the garnets from the substrate without harm and it is their round soccer ball shape that makes them work so well. I have no proof of course, but it seems to work for me, so that's my theory.

I do use a diamond plate to initially flatten a coticule (I did it once, maybe 15 years ago) and after that I have cleaned the surface with a cotigura and only use that for cleaning, raising a slurry or refreshing the surface. My coticule is rather hard and does not seem to auto slurry like many of them do, so it has not dished on me. But even if it did, it would have a long way to go based on the old hones we occasionally find that were used until they looked like a saddle.

Regards

Christian

Originally Posted by kaptain_zero

dinnermint makes an excellent point that I too have followed.

I NEVER use a diamond plate for raising slurry on a coticule, only another piece of coticule as a slurry stone. Why? Coticules are made from larger garnet crystals (think glass) and sharp shards of diamond will easily fragment those garnets, leaving sharp pieces in the slurry or sticking out of the substrate. Gently using a cotigura (small coticule hone meant for raising a slurry) will be more likely to release the garnets from the substrate without harm and it is their round soccer ball shape that makes them work so well. I have no proof of course, but it seems to work for me, so that's my theory.

I do use a diamond plate to initially flatten a coticule (I did it once, maybe 15 years ago) and after that I have cleaned the surface with a cotigura and only use that for cleaning, raising a slurry or refreshing the surface. My coticule is rather hard and does not seem to auto slurry like many of them do, so it has not dished on me. But even if it did, it would have a long way to go based on the old hones we occasionally find that were used until they looked like a saddle.

Regards

Christian

I do remember reading and seeing a magnification of the garnets when broken up with a DN vs coti slurry stone. It was advised not to use a DN for slurry, though many do and either don't notice a difference or don't know the difference.
It is in the article grinding and honing part4 belgian whetstones.

Originally Posted by kaptain_zero

dinnermint makes an excellent point that I too have followed.

I NEVER use a diamond plate for raising slurry on a coticule, only another piece of coticule as a slurry stone. Why? Coticules are made from larger garnet crystals (think glass) and sharp shards of diamond will easily fragment those garnets, leaving sharp pieces in the slurry or sticking out of the substrate. Gently using a cotigura (small coticule hone meant for raising a slurry) will be more likely to release the garnets from the substrate without harm and it is their round soccer ball shape that makes them work so well. I have no proof of course, but it seems to work for me, so that's my theory.

I do use a diamond plate to initially flatten a coticule (I did it once, maybe 15 years ago) and after that I have cleaned the surface with a cotigura and only use that for cleaning, raising a slurry or refreshing the surface. My coticule is rather hard and does not seem to auto slurry like many of them do, so it has not dished on me. But even if it did, it would have a long way to go based on the old hones we occasionally find that were used until they looked like a saddle.

Regards

Christian

Now I kind of wonder if that isn't why my coticule is extraordinarily upset with me. Tried taking an edge up to 12K, then bumping over to my coti. Shave was awful. I lapped it flat with a diamond lapping plate, then 'burnished' it with the rubbing stone to get rid of the scratches. Maybe I still have broken garnets exposed. Hmmm...now the question is, how do I go about fixing that. Might be worthwhile to scrub it with the rubbing stone some tonight under running water.

Originally Posted by Marshal

Now I kind of wonder if that isn't why my coticule is extraordinarily upset with me. Tried taking an edge up to 12K, then bumping over to my coti. Shave was awful. I lapped it flat with a diamond lapping plate, then 'burnished' it with the rubbing stone to get rid of the scratches. Maybe I still have broken garnets exposed. Hmmm...now the question is, how do I go about fixing that. Might be worthwhile to scrub it with the rubbing stone some tonight under running water.

Just keep using it the right way and over time it will forgive you.

After lapping a coticule will be more aggressive and faster. It will calm down with some use and using the slurry stone under running water can help tame it again.

Originally Posted by kaptain_zero

dinnermint makes an excellent point that I too have followed.

I NEVER use a diamond plate for raising slurry on a coticule, only another piece of coticule as a slurry stone. Why? Coticules are made from larger garnet crystals (think glass) and sharp shards of diamond will easily fragment those garnets, leaving sharp pieces in the slurry or sticking out of the substrate. Gently using a cotigura (small coticule hone meant for raising a slurry) will be more likely to release the garnets from the substrate without harm and it is their round soccer ball shape that makes them work so well. I have no proof of course, but it seems to work for me, so that's my theory.

I do use a diamond plate to initially flatten a coticule (I did it once, maybe 15 years ago) and after that I have cleaned the surface with a cotigura and only use that for cleaning, raising a slurry or refreshing the surface. My coticule is rather hard and does not seem to auto slurry like many of them do, so it has not dished on me. But even if it did, it would have a long way to go based on the old hones we occasionally find that were used until they looked like a saddle.

Regards

Christian

It would seem to me if you used diamond on a coticule the hardness of diamond is so much greater than the matrix and the garnets the diamond would quickly pulverize the garnets and force them to be released at a much greater rate. The softer the slurry stone the fewer garnets released and the more likelihood the garnets would retain their xtline shape.

Just a guess.

I love my three coticule. Each is a select grade. I do have my preference though. My advice is not so much on the purchase of one but the learning to use it. Read and watch videos all you can. I recommend the follow four part series by drmatt357 from YouTube in your research. The embedded video is part four, which I regard as the most informative. You can find the first three parts yourself.

https://youtu.be/to5Z-EFGDBY

Dieseld - seriously considered it a time or two. But even at a discount I wouldn't wish this curse on another if this rock is as bad a razor hone as I think it is. And if it isn't then I want to figure out what I'm doing wrong with it.

Might still be an excellent knife/tool hone. It cuts steel quick and polishes decent. Just doesn't make a comfortable shaving edge.

Was kinda messing with ya, but..........


I'm a gluton for punishment

Marshal, check out this video. He goes into problem coticule stones

https://www.youtube.com/watch?v=to5Z-EFGDBY

oops same one Laonhaultanker posted.


But this guy is good explaining the stones and how he gets the best edge