Quote Originally Posted by onimaru55 View Post
I'm also curious as to why the bevel gets more polished & the scratches get finer if the slurry doesn't break down as the blog postulates.
It isn't stated anywhere in the blog entry on Japanese natural slurry that "the slurry doesn't break down". What he says is:
Quote Originally Posted by Todd@scienceofsharp
In conclusion, there is no evidence that the silica (abrasive) particles “break down” or become finer with use. The soft clay binding material of the stone, composed of phyllosilicate material, does break down into individual flakes.
Note: No firm conclusion, just that he did not find evidence of silica particles breaking down or becoming refined through use using his methods. No more, no less.

He addresses it further in a comment:
Quote Originally Posted by Todd@scienceofsharp
scienceofsharp says:
January 14, 2015 at 3:21 pm
I don’t believe there is any controversy as to whether the slurry changes consistency with use, becoming “less abrasive.” This is an accepted observation.
However, the only change we observe in the slurry is that the phyllosilicate component decomposes into thin sheets.
The silicate particles may be slightly abrasive, but the combined effect is expected to be dominated by the abrasiveness of the silica particles.
So, yes the phyllosilicate particles almost certainly play a role, but the physical mechanism has not been established.
He is quite clear in this.

As far as the scientific criticism goes, I think he could be doing much worse. He defines his terminology, carefully examines his subject and clearly states his methods, so they can be reproduced. On claiming new insights, I couldn't find other than he states that "The goal is to provide an understanding of what is happening a [sic] the blade’s edge", but I might have missed something.

I don't feel he's 'soapboxing' by any means. He engages in discussion in the comment section and doesn't come off as preachy or highly opinionated. I haven't yet read all of it, but what I did read was interesting at the very least.