Maruoyama shirosuita grit range?

[shobudonnie]

Around what grit range is a typical shirosuita from Maruoyama mine? I know that ohira and Shoubudani typically falls into the 8000ish range. And Maruoyama shirosuitas are supposed to be softer/less fine. So maybe around the 6000ish range?

And if it is around the 6000ish range, what would this natural stone offer that a synthetic 6000 stone like the gesshin or jns 6000 couldn’t?

 

[ethompson]

There is a bit of range from about 5ish k on the low end up to 6.5-7ish for the finest examples. Grit equivilent is a tricky thing with natural stones, so this doesn't tell the full story.

What happens on the edge certainly isn't what happens with the finish when it comes to polishing. While an edge from a good 6k stone (like the ones you mentioned) and a Maruo shiro might be similar, the finish will certainly not be. A Maruo or similar soft / "coarse" suita will leave a very clean finish on hardened steel and good base on soft cladding. Transitioning from Maruo to an Ohira or Shoubu will be a seamless, easy process assuming the base work is well done. Creating kasumi with the first stone being finer suita following a 6k is usually a tedious process as cleaning the core steel well can be a drawn out process.

TL;DR - If you're sharpening a 6k synthetic and soft Kyoto suita (of which Maruo shiro is probably the best readily available example) do pretty much the same job, especially if it is not the finishing stone. They aren't readily interchangeable in a polishing progression.

 

[lesslemming]

ethompson nailed this response.

To me, there are basically two reasons to get excited about JNATs:

1. You are a purist: Experience the mystery of what Japanese togishi have been doing for centuries.
2. You are an aesthetic: You are looking for Kasumi polish or would like to tickle out as much detail as possible while also being a purist.

To answer your question the way I would have phrased it:

Where in the progression does a Maruoyama Shiro Suita typically fall?

It comes after the bevel has been set and is clean.
It is recommended to either use a Nakatoishi like an Aoto, Natsuya or Aizu before proceeding to something like a Maruoyama Shiro Suita.
Of course a Maruoyama Shiro Suita can also be used after an equivalent synthetic sharpening stone in the range of 2k-4k.

Personally, I have always felt the Shiro Suita from Maruoyama are finishers in their own right, both for sharpening and for Kasumi / polishing work.
But of course one can go a step beyond with an even finer and harder Awasedo or particularly fine Suita like a Nakayama Suita.

TLDR: The Maruoyama Shiro Suita is usually considered right on the border of being a finisher.