This is the second installation of the Wicked Edge Precision Sharpener’s (WEPS) progression of stones under the microscope. In this post, we will look at the complete Chosera WEPS stone progression. You can find the microscopic progression of the WEPS stock diamond and ceramic stones here. I highly recommend reading the stock progression first, as it contains information that will be applied to this post.
The knife is a Maestro Wu bombshell steel folding knife with the angles set to 20 degrees per side. All pictures are taken with a Veho 400x USB microscope, and the actual dimensions of the pictures are all 1mm wide by 0.75mm high.
On a new knife, or one I am profiling for the first time, I would normally start my Chosera progression after the stock 600 diamond WEPS plate. And according to this grit comparison chart, it is a clear step backwards to go from the 600 WEPS (16 microns) to the Chosera 400 (30 microns). But as we saw in the WEPS stock progression of the 1K WEPS diamonds to the WEPS 1200 ceramic, the depth of the scratches on the diamonds can be pretty deep, and while the 400 Chosera stones may be coarser, they will not scratch as deeply – so your deepest diamond scratches begin to be exposed and worked out at much lower levels. The 400 (and 600) Choseras are also excellent for doing maintenance and routine repairs without using the diamonds. While I know not many people will be convinced to go back to the 400 or 600 Choseras, this step back actually excels the sharpening process as it moves forward.
As usual, I will be doing a series of scrubbing strokes followed by sweeping strokes at each grit. Scrubbing strokes are aggressive, and are an up-and-down motion used to establish the scratches at each grit, and to account for any minor deviations due to the tolerances of the angle cube, and dishing in the stones, etc.. The sweeping strokes are alternating strokes the span across the entire edge from heel to tip or tip to heel, and they establish a straight line at the edge of the edge. I don’t generally use circle strokes with anything other than the WEPS 100 diamonds.
One thing I do with my coarsest Chosera stone (which may be the 400, 600, 800 or 1K Chosera, depending on the situation) when coming off the diamonds is to first use the stone with a slurry. A slurry is generated by rubbing two same-grit stones together (they should be pre-soaked and wet already). In this case, I rubbed the two 400 grits together. This releases 400 grit abrasives onto the surface of the stones, and makes them more aggressive. While they do arguably cut deeper (since the full size of the abrasive is loose as opposed to just a portion sticking out of the matrix), it will still not cut as deeply as the diamonds. It will not be “best” representation of the edge, either. At this early stage, I don’t worry about making the edge usable yet. For me, it’s the transition from the diamond scratches to the Chosera scratches that is key.
Below we have the 400 Chosera with slurry.
It’s hard to tell at this level what is lurking underneath as the slurry on the stones makes things rather “dirty”. Things do clean up better with the 400 Chosera sweeping strokes:
While the bevel is clearly smoother than the diamond finish, the edge of the edge is rather toothy and serrated. This is because of the slurry. If I wanted to stop at the 400 Chosera, I would not use a slurry. We’ll get to that in a little bit 🙂
Next, the 600 Chosera with water only (no slurry) scrubbing and sweeping:
After the 600 WEPS, we can clearly see that the scratches are Chosera, and not Diamond scratches.
There is really not a whole lot of difference between the 400 and 600 Chosera stones other than the 400 is “harder” and generally better suited to softer knives while the 600 is “softer” and generally better suited to harder knives. FWIW, I personally like the 600 more than the 400 🙂
The 800 Chosera is an excellent “lateral” move from the WEPS 600 diamonds. I would use a slurry if I were coming straight off the WEPS 600, but since I am following the Chosera 600, I only used water.
There is an uncanny similarity to the 800 Chosera and the WEPS 600 Diamond finish at the edge of the edge. However, the polishing effect of the Chosera cleans up the face of the bevel, making it shine more. They are both very clean and ready for cutting at a basic sharpness level.
I want to take this moment to explain slurry and paste regarding the Choseras specifically. Slurry is loose abrasive that makes abrasion faster. On the Chosera’s it has a milky consistency that is roughly the same color of the stone. Because the abrasives are loose and there are a large amount of them, I reserve slurries for the coarsest grits, and do not use them past 1K. Paste is the black buildup on the stone that accumulates as you use it. It is a combination of water, abraded metal, lose broken down abrasive that has been released from the matrix naturally (not through raising a slurry), and bits of the binder. On the Choseras, a paste is desired. It is a finer abrasive that serves to “polish the grooves” of the scratches while cleaning up the edge of the edge. This leaves the edge more refined than the advertised grit. The trick with paste is to keep it wet enough so it stays on the stone without dripping off. Also, the more strokes you do, the more refined the edge gets (but not infinitely).
(Paste is often called swarf, but as we’ll see in the Shapton WEPS progression, Swarf is the mixture of abraded metal and water that is not desired.)
In the case of the Choseras, the scrubbing action at each grit helps to create a paste, which then makes the sweeping strokes finish finer. It’s a fantastic 1-2 punch! 😀
Now we will continue with the 1K Chosera:
The 1K Chosera is a wonderful stone for a working edge. It is often referred to as the “incredible hulk” since it bleeds green 😀 You can see how smooth the bevel is, and how clean the edge of the edge is thanks to the effects of the paste.
The 2K Chosera may look a little rougher than the 1K Chosera, but the edge of the edge actually comes to more of a point than the 1K, and roughly equivalent to the WEPS Ceramic 1600 (although I think the 2K Chosera looks a little better). Again, the paste has enhanced the performance of the stone, and there is actually a very nice mirror on on the bevel at this point, although the actual scratches are not even enough at the microscopic level.
A lot of guys swear by their 2K Chosera as the best all-around working edge, and the 2K sweeping picture shows why. 😀
The 3K Chosera scrubbing picture begins to reveal some of the deeper scratches left by previous stones. Even though the Diamond scratches were well removed, you still have the earliest Chosera scratches to contend with. In fact, revealing and removing previous scratches is a fact of life with any progression.
The 3K sweeping is not much different than the 2K, although there is a thinner edge of the edge and the bevel is smoother, still. As we approach a microscopically smooth surface, the more “blue” the edge becomes. When it turns white, then we have achieved a a real mirror finish.
Much like the relationship between the 400 and 600 Chosera stones, the 2K is “softer” and more forgiving, and is generally better on harder knives while the 3K is “harder” and less forgiving, and is generally better suited for softer knives. Both the 2K and 3K progress to the 5K with no problems.
The scrubbing at the 5K Chosera level exposes the scratches quite cleanly while the sweeping creates a very smooth surface. At the macro level , this is a full mirror, but at the micro level the surface is not quite clean “enough” to give that mirror effect.
That brings us to the “critical leap” concept. In any progression, there will be a transition where the peaks and valleys are even enough to reflect the surface cleanly. Medium grits still create scratches that won’t reflect directly whereas polishing stones scratches will. This transition is the “critical leap”. On the Chosera progression, you have a visible mirror at the macro level by the 2K level, but not yet under the scope. The critical leap on the Choseras is therefore between the 5K and 10K levels.
Because the critical leap on the Choseras is between the 5K and 10K levels, it requires more strokes to perfect things since we are using the”slower” 10K abrasive size to abrade. The paste from the 10K leaves a slightly “imperfect” looking bevel and edge. Believe me, the bevel is a complete mirror thanks to polishing effect of the paste. The resulting edge is a little toothy due to the scratches, but very smooth due to the polishing of the grooves with the paste.
From here, you can definitely shave your face, or continue on with pasted paddles or Shapton stones.