Matus - I hesitate to say that is the case. The only 2 knives I've used on these T-nats so far as that wide beveled project/beater knife (carbon core, soft iron cladding) in the picture as well as a 52100 monosteel narrow beveled project knife. These are knives that I mess with on almost a weekly basis practicing sharpening, thinning, polishing, and testing different stone finishes. As such, they indeed tend not to have patina most the time and so I'm used how to manage that during sharpening.
On the monosteel knife, I recently polished up the sides to 320 or 400 grit 3M sandpaper which had it kind of shiny. I sharpened that one with a white binsui with some tomo nagura slurry (after that pass, no problems, no patina) and then the khao men. Every place on the blade face that the khao men slurry covered for no more than a few minutes had turned almost milky white, huge contrast to the polished remainder of the blade face. I've never had that much change to that monosteel knife in the course of a sharpening on one stone.
And then on the wide beveled knife, the cladding rusted faster than I'm used to. I have started wiping after every polishing pass on one side (1-3 minutes) after the khao men though I do not have to do that on other stones.
I had reservations about mentioning this feeling/suspicion but decided to write it anyways in case for some reason this isn't an isolated occurrence or that it's not totally in my imagination. Is there any precedent for acidic inclusions in natural stones? My Khao Men has some streaky white coarser stuff running vertically along one end of the sharpening surface. At any rate on that stone I'll be wiping every minute or two at the longest to try and avoid having problems.
Today I did a little more thinning and polishing on that wide beveled knife. Naniwa Pro 400 ->Thai Orange Binsu -> Gesshin 2000 -> Khao Men. Freed but a little bit more of the core steel towards the middle and front of the knife. Took a few pictures
https://drive.google.com/file/d/1JsPVE8ewL1JBiETImGXapiqFqGvifrRGGg/view?usp=sharing This is after the orange Binsu. Mine is definitely on the harder side and acts much like a coarser version of the white. It doesn't shed abrasive all that readily and instead the surface tends to burnish, similar to the white binsu I have. I was hoping it would act more like a bigger, better quality red binsui/red amakusa which I have a small block of and will actually generate something of a slurry/paste. As you can see in the picture the mud is basically all swarf, though with some swarf and a good water buffer you can use this for some polishing. Added a great deal of contrast following the Naniwa Pro 400.
https://drive.google.com/file/d/1LPlcplSK7_QDhHP_jfrNThuWUJWeiTyg9Q/view?usp=sharing This is the Khao Men finish following the Gesshin 2000. Smooths out the scratch pattern fairly well. Cladding color is darker and core steel color hasn't changed much compared to coming off the Orange Binsu which diminishes contrast a bit though obviously the scratch pattern is actually finer. Hopefully there's a bit more core steel visible to get an idea of contrast in this picture compared to the earlier post. Still forming my opinion on this, but at this time I'd rate the Khao Men I have as something in the 2-5k, maybe 3-5k range. This and another natural I have both remind me of the edge and finish similar to that of Suehiro Rika.
Here are pictures of all 3 stones dry and then wet.
https://drive.google.com/file/d/1UCKGxNE8Lv4X18zXrJ0dNW5GfEQD_Eb8Fw/view?usp=sharing
https://drive.google.com/file/d/1h_xpoOZOB7xOO2nSR_of0y0t9BVLHgNgLQ/view?usp=sharing
I realized that I forgot to specify that I wanted to get a softer pastier orange binsu as opposed to a harder one, got too caught up specifying dimensions to fit my budget range. I feel that my orange and white are kind of close together in grit and overall usage.
https://drive.google.com/file/d/1hbHnffjiLSLXaRUYIEFSkVunwmGkwIDmng/view?usp=sharing
This picture shows a slight chip in a corner of the white binsu which reveals a deep orange color so clearly I got a 2-in-1 stone
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I may have to make another purchase to grab a softer orange binsu...