Part 2:
Identifying Coticule layers is a bit like identifying mushrooms.
We could sketch up a sort of taxonomy, but without proper experience, misidentification is very likely, all the more when one can only go by pictures. That said, I'm not one to withheld information, so her goes:
Start with reading this thread, it contains information about the Ol' Preu quarry.
I am following the numbers of the layers as they are listed in that thread. We have to start at number 4, because the first 3 are depleted, 4 is becoming rare, and 5 extremely rare at that particular location. Since Ardennes is currently only extracting Coticules at that location, there are no specimen available from other layers.
4. La Grosse Blanche.
Pale colored Coticule layer, that turns deep brown when exposed to (sun) light for a prolonged time. Black manganese lines and dots may be present. Sometimes brown needle-spots, spread over part of the surface, resembling pores (although the surface is non-porous). Slurry has a characteristic soapy texture. Speed on slurry is fast to moderate. Speed on water generally very slow, but the presence of said brown spots predicts a faster behavior on water. Usually much "slurry dulling", but mellow, skin friendly edges when finished on water.
5. La Grosse Jaune (presumably called La Gros Grés by Dumont)
Coticule has a yellowish gray color that turns ochre yellow when wet. Presence of a grainy-looking pattern (although completely smooth to the touch), that is finer than that of La Grise (see there) and more reminiscing of wood pores than of wood fibers. On slurry this is one of the slower layers. On water the stones are slow, with a "magnetic" draw that resembles the "hybrid' side of Les Latneuses. Slurry has a consistency as if a lubricant was add. La Grosse Jaune Coticules are among the easiest to get perfection during the final honing stages.
6. La Dressante
6a. La Dressante au bleu
Always a combo with BBW. separation line sharply defined, and often curved. Coticule has a coffee-with-cream color, a bit darker than the rest of La Dressante. Possible presence of black manganese lines and dots. Possible prescence of red or orange lines. Surface of Coticule is not patterned, some bluish blotches may be present. Speed on slurry is moderate, about in the middle of the spectrum. Slurry dulling is mild. Speed on water is slow (some discoloration of the water after a set of halfstrokes).
6b. La Dressante Upper Layer
The part of La Dressante that is not connected to the "lower" BBW part, hence mostly glued to slate. The most variable of all layers. Color can vary from pale to pink. Hues sometimes present in one stone. Manganese lines and dots possible. Manganese hairlines seem to predict very fast performance on slurry. Red, orange and yellow lines possible. Red lines seem to predict (relative) fast speed on water. No surface pattern. La Dressante upper layer has a clear feedback that transitions from textured on slurry to almost icy on water. Speed can vary from moderately slow (rare) to fast (very common) and occasionally very fast.
7. La Veinette.
A very narrow layer, always bonded to BBW (unless the BBW is defect and they have to glue to slate). Creamy Coticule part, no surface pattern. Often manganese lines or dots. BBW caries short or longer white stripes at the lateral side, parallel with the separation line. Abrasive properties very consistent throughout the layer. Moderately fast on slurry and (relative) moderate to slow on water, which means that it will darken the water before the end of one set halfstrokes. No much slurry dulling, which makes them easy to use. Typical feedback, grainy feel on slurry that evolves to a slight draw on water.
8. La Petite Blanche.
The second one of the narrow layers, always bonded to BBW. Pale creamy color, no surface pattern. Characteristic blue line running at the lateral side of the Coticule part. Often purplish parts in the BBW near the transition line. Manganese lines may be present. Abrasive properties very consistent throughout the layer. Fast on slurry and (relative) moderately on water.
9. Les Latneuses.
A twin layer, consists of one "hybrid" part, sandwiched between 2 Coticule parts. Delivers combination stones "hybrid"/Coticule, and Coticules glued to slate. Hybrid side helps identification. Coticule is coffee-with-cream colored, manganese lines and spots possible. Sometimes orange-brownish lines. Also more pink colored Coticules with lighter yellow lines and dots. These are strikingly fast on water. One side of Les Latneuses has series of blue hairlines running laterally in the Coticule part. This side is moderately fast on slurry. The other side has far less occurrence of these blue hairlines, and is very fast on slurry. Speed on water of Les Latneuses is variable throughout the layer. Coticule sides have in their feedback distinct textured aspect. The hybrid side is moderate speed on slurry, and has a different feedback, that is often described as "magnetic" on water only.
10. La Nouvelle Veine
Thicker layer that allows several slices of Coticule to be cut. Pale creamy color, often blotched with hazy blue spots. No real pattern as seen on La Grise, La Verte or La Grosse Jaune. Typical are a series of faint blue hairlines running in the lateral side of the Coticule part, parallel with the separation line (or glue line). Abrasive properties on slurry vary from slow to fast, depending on which part of the layer you got. It appears that on one side near the adjacent BBW, the layer is fast, while the stones bonded to the opposing BBW are slow. La Nouvelle Veines with a gradual transition to BBW are fast. The ones with a prompt transition are slower. Glued specimen can be anything in between, but generally are fast. On water, La Nouvelle Veine Coticules are slow to very slow. Fast-on-slurry La Nouvelle Veines exert much slurry dulling and require precise dilution to yield perfect results. They have that in common with La Grosse Blanche. It appears that these stones oblige the user to get it right, in which instance they deliver outstanding, mellow edges.
11. La Grise
Thicker layer that allows several slices of Coticule to be cut with consistent properties throughout the layer. Color mostly warm (yellowish) gray, but cool (bluish) gray occurs as well. Presence of a grainy-looking pattern (although completely smooth to the touch), that is reminiscing of wood grain. Natural combination stones mostly have a gradual transition to the BBW. Many La Grises are glued to slate. Speed on slurry centers around moderate, sometimes a bit faster, but usually slightly slower. Speed on water is (relative) slow, which means that the water will show signs of darkening after a set of halfstrokes, but not with regular (low pressure) X-strokes. La Grise Coticules have a glassy feel on water only, and mild slurry dulling. They are easy to yield good keenness.
12. La Verte
Thicker layer that allows several slices of Coticule to be cut with (mostly) consistent properties throughout the layer. Color is of a distinct greenish gray hue. Natural combination stones have a gradual transition to the blue of their BBW part. Presence of a grainy-looking pattern (although completely smooth to the touch), that is reminiscing of wood grain. They are both in look and feel related to La Grise, albeit La Verte Coticules are generally harder. Speed on slurry centers around moderately slow. They are faster on water than La Grise, which makes them excellent touch-up hones, and they can make up on water for neglected work in earlier honing stages.
13. La Veine aux Clous
Only 2 specimens tested so far. These were quite soft, slightly porous with an open texture that gave them a granular feedback. Very slow on slurry, with a lot of extraneous slurry release during the honing process. Bevel correction capabilities were limited, finishing, when performed under a running tap (to counteract the auto-slurry release), was on par with what I expect of a Coticule edge. This layer is - to my knowledge - not commercially exploited, but for completeness sake, and because it has a name, I am sharing this information for what it is worth. I repeat that I only tested 2, nearly identical, specimens of this layer.
Bart
