Thread: Looking for info on a speckled Coti

Originally Posted by TwistedOak

thanks Hirlau! Any thoughts on it's cutting speed?

I don't really know a lot about speeds on a stone, only 2 years into this honing experience. I have finished about 6 razors on it now. Coming from an 8k, I get a beautiful shave at about 35 strokes. I have touched up 2 razors with 10 to 12 strokes, to get back in the game.

Compared to my PHIG, it's like the Concorde was from New York to London.

Nice looking stone. I have some that are tiger stripped. I would think it'd be on the fast side as well. Create some slurry. Take an old razor and do "back strokes" See how fast the slurry darkens, That's a good indicator of it's speed. 10 or less strokes, very fast. You can check the stone itself by scratching it with your fingernail. If you see a nice clean mark, it's soft. If you see nothing, it's hard, and in between, well you get the idea.

La grise can have big bright orange spots on the surface but I can not say yours is one because it is an old mined coticule. Coticules mined decades ago can not be ID'd because the names are long lost.

Old coticules selected for razors had a certain combination of hardness vs softness vs garnet content, which is why some of us prefer older coticules labeled for razor use.

For example harder coticules may have less garnet per square inch than softer coticules thus making them more suitable for tools and knives. If you asked Maurice today for a coticule for razors he would pick one based on a degree of hardness vs softeness for razors.

Hard coticules- less garnet per square inch but agressive cutting power.
Softer coticules- more garnet per square inch, finer polishing ability but not much cutting speed.
Perfect balance of those two is what you want for razors and older mined coticules were sold for razors after being tested for that purpose.

Originally Posted by Disburden

Hard coticules- less garnet per square inch but agressive cutting power.
Softer coticules- more garnet per square inch, finer polishing ability but not much cutting speed.
Perfect balance of those two is what you want for razors and older mined coticules were sold for razors after being tested for that purpose.

That's not my experience, I'm afraid! When I used to talk to Rob from Ardennes Coticule that was pretty much his opinion, too (I mean he agreed with me - harder is finer). I suppose there are always exceptions, though.

I find that harder coticules give a finer finish - my Les Latneuses is as hard as they come, and still manages to be a fast cutter and the finest coticule finisher I have ever had - and I have had a lot! I have one that is only slightly less hard, and which is a slow cutter, but it is a very good finisher. These two give an edge that is very un-coticule like - very sharp indeed with hardly a hint of the soft, rounded bevel edge that you usually associate with coticules.

The softer coticules that I have owned all had good cutting speed, but left an edge that was too soft and mushy - the softer ones lose garnets quickly, and the slurry rounds the edge. Hence the fact that most people progressively water the slurry down to impede the rounding effect. With some soft coticules you cannot really stop the garnets being released - they 'auto-slurry' and the water picks up a mistiness within a few laps. Some auto-slurry so much that they are useless for razors, except for coarse work.

I have had a tiger-striped one that had the same colour in the stripes as the OPs has in the dots - that was a fairly fast cutter, and a decent finisher.

Regards,
Neil

Neil. I respect your knowledge and experience with coticules but I am just reiterating what Ive been told through emails from Ardenes themmselves and how they judge a eazor stone compared to a knife stone. I was told majority of the time a harder stone has less garnets but as larger in size compared to a softer stone with a larger garnet content. Of course there are exceptions but that is the majority rule I am told.
I was told told by Maurice though that once a stone becomes too soft you need to finish under running water or in a pool of water to escape the auto slurry effect.

No problem - exchanging knowledge benefits us all! Even if it doesn't, a frank exchange is very welcome.

I find it odd that Rob's opinion is at variance with Maurice's.

Not that I'm taking issue with the amount of garnets a coticule has in it - what I have observed is that harder = a finer edge.

FWIW I think that the matrix (binder) is more important in determining the type of edge you can obtain. A soft matrix releases garnets quickly, whereas a hard matrix does not. As it is the free-floating garnets that are rounding the tip of the bevel and at the same time accelerating the cutting power of the stone, then it follows that a soft coticule (soft matrix) cuts quicker but not as finely as a hard coticule (hard matrix).

No doubt there are all manner of deviations, such as a hard matrix with a high garnetcontent and a soft matrix with a low garnet content (BTW, I believe that there are some intermediate layers with no garnet content whatsoever), but all things being equal I can't help but find it self-evident that a hard coticule that is not releasing garnets at a great rate of knots is not going to round the edge like a soft one that throws the garnets out like there's no tomorrow.

With regard to the amount of garnet in each, I can't see that you can tell what it is without some sort of analytical tool like a microscope or for purely coticule layers (ie no natural combo stones) by measuring the Specific Gravity of a stone, but allowances would have to be made for other depositions within the stone like manganese inclusions, quartz, etc, etc - I should imagine you would have to be some sort of research chemist to make this workable. You certainly can't see individual microscopic garnets with the naked eye. Most people tell what is what by attempting to scratch the surface of the coticule with a fingernail to determine soft from hard.

What you say about running water/pool of water makes sense - though in all honesty I would rather ditch the coticule and get a stone more suited to the task. I'm afraid that I no longer see anything romantic in hones - they are just tools to me.

Regards,
Neil

The boxed 5x1 looks like it might be a Thuri. I have an Escher like that.

Originally Posted by Pyrateknight

The boxed 5x1 looks like it might be a Thuri. I have an Escher like that.

That is actually the backside of this coticule, after cleaning it's more reddish/burgundy.

Thank you everyone for the information! I'll do what I can to see how hard it is and how quickly it cuts.

Interesting stone. I have one that has speckles on it that I was told was not a real coticule. Was told it is a man made stone of some sort. There is a test that is done to see if in fact the stone was natural or man made. Using some CLR I put a drop of it on the stone which reacted to the binder (so I was told) and created bubbles. This indicates (so I am told) that the stone was indeed a man made stone.

A couple of pics on the one I am referring to.