David, I'm in the middle of doing experiments. Under a scope, the scratch patterns from different coticules (2 bought from Ardennes, 1 vintage, and 1 other) show a striking variance.
As for how this all correlates whit the actual edges of these hones touching the face, I can't tell anything conclusive, since testing only recently started, but the first results seem to be in line with what can been seen under magnification.
The thread is here: http://straightrazorpalace.com/advan...-pictures.html
In my "coticule diaries", I wrote about Ardennes' grading system that has nothing to do with the actual honing properties from the stones, but only with the cosmetic appearance, except perhaps for the "Kosher" quality. They are aware of this, at Ardennes, and have plans for installing a grading system that reveals the actual layer that a particular coticule is harvested from, which correlates much more to its honing properties. In fact, a member of this forum recently bought a "Kosher" coticule and it came with the name of the layer written in pencil on the hone. I also received a small one from them myself, as a present that came with an order, that had a "layer designation".
Bart.