Carbide popout is a finicky thing… even with all diamonds.
You run into several issues as you add more refinement to abrasion resistant steels. The first is that There is a point of diminishing returns with the more abrasion resistant steel – the higher you go in grit, the slower it abrades. Of course diamonds still cut, but they will progressively slow down at each grit level.
More importantly, the diamonds abrade through the carbides once the abrasive becomes smaller than the size of the actual carbides – I don’t know for sure what that size is, but I am guessing somewhere between the 4K and 8K range (2-4 microns) based on my observations (which is by no means extensive in the super steel area) – In theory, this can cause carbide fracturing, where the comb-like gaps in the carbide itself become too unsupported and snap off like a pencil point, leaving you with a “whole” thickness of carbide again that is still secured to the steel. This theory seemed to be proven with my recent attempt to sharpen an s90v Spyderco military knife to shave ready. I’d get it to a certain point, where it was screaming sharp, and then the edge would disappear on me.
With the surrounding steel being rather “soft”, I found that while it was difficult to abrade through the carbides, the steel itself was still rather flexible, and I could feel the edge had rolled somewhat after stropping (since I was going for a shave, I used lower angles and the edge of the edge became very thin).
The solution was to add angles to the steel as I went higher in refinement. This accounted for all the issues presented here. The higher angle allowed the carbides to be abraded through with finer grits, but left enough structural stability in the serrated carbide to not fracture. It also solved the issue of rolling the edge that was too thin for stropping. I ended up at about 35 degrees per side for my shave on the s90v.
ZDP-189 may react differently, but I think they will follow the same route.
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