Originally Posted by
Russel Baldridge
To address your issues with the coticule, it's surprising to me that you don't see any difference between edges honed on a coticule with slurry as compared to those without slurry. I notice a difference with no magnification at all. The slurry produces a hazy, dull bevel, and no slurry (just water) makes polished linear scratch lines. Distinctly different with no need to magnify.
And yes, the coticule is said to cut like a 6k to 8k hone with a slurry and like an 8k to 10k hone without slurry. The grit size is not changing, just the speed at which it abrades the steel, which is comparable to stones/hones in lower grit ranges.
Raise a slurry and see how fast it turns black when honing, then try to get the same amount of blackness on the coticule without a slurry. It'll take a lot longer because the slurry is abrading much faster than the plain stone's surface. (don't do this on a good blade, use one in need of a resto or a junker).
Also, the slurry does abrade the cutting edge, which is why it isn't recommended to use the coticule with slurry as a finishing step. It is a "rough cutting" step before polishing with the coticule and water.