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Carbon content is related to utsuri no doubt of that, a 0.45% C can't produce utsuri, while over 0.7% can. Anyway I shared enough of my personal experience and Japanese swordsmiths experience, the readers can decide what they think works better. The topic is already exhaust for me

I don't see any mention to utsuri or hamon in the article, I don't know how can be relative to the utsuri topic. This process shows how grain size changes during cycles of normalizing and annealing. The grain size doesn't affect the appearance on the ji, it might influence the hamon in some degree, but depends on how the yakiire is performed

I would say not a common way to make utsuri, also not much reliable, but it still can work, since the principle is the same, different temperatures when cooling rapidly

Midare utsuri Bo utsuri

Exactly, any form of forging and hardening is a thermocycling, but what he stated in his first post is a series of process of heating and cooling with application of clay prior to the yakiire that would lead to the creation of utsuri. I just want to know where this information comes from and how it should look like when it's done. Because so far the only way I know to create utsuri is by temperature control during yakiire. It's not something I claim, it's been done by several swordsmiths, not only Japanese

Of course any form of hardening is a thermocycling, because it changes the composition of the metal through heating and rapid cooling, what I mean is that specific process you described in your first post. Can you provide an example of blade made that way and how you know that process has been used on it?

I have close to 1TB in my library, you gonna need to be more specific on what you want me to show you. Meanwhile can you show me some examples of what you assume is an utsuri created by thermal cycling?

I already showed several examples, but apparently they're not utsuri? I'm not trying to fight or being petty, just I'm sharing my first hand experience, and those who say I'm wrong provided no evidence of what they're saying.

I'd say with the same steel a blade with utsuri has more resilience, so can withstand hits without breaking, more than a blade without. Sharpness is due the hamon so not directly influenced by utsuri. I agree with Kiita saying that first times could had been accidentally created by trying to avoid heating the blade too much and for too long time, but then became a feature when they figured out it worked better on the battlefield

Kapp never mentioned cycling in the book, it's heating at different temperatures at the time of yakiire, which is the same I said in my first post. So if nobody did that in modern times, how do you know it was made that way back then?

Just to understand, is this utsuri to you?

So where are the blades that we know for sure are made with this method?

Yes but doesn't create hamon nor utsuri from what I know, do you have any actual example of hamon and utsuri create by this method?

same blade as the same picture, not a second hamon. I know how to look at utsuri another blade from same swordsmith, is this "real" utsuri? Who made this theory? Do you have any evidence or experiment about this process? This sounds an overly complicated process for someone who wants to reduce the risk of mistakes during hardening, not to mention this might give some extra internal stress. This would not be easy even with modern day tools.

I never said he did master the old koto masters utsuri, and anyway those are just two examples that I actually own. This topic isn't about who made the best utsuri, but how utsuri is made