Thread: Natural Stone Grit Confusion

Originally Posted by JimmyHAD

A blast from the past .... here are photos taken by Tim Zowada of various hones and the edges of various razors sharpened on those hones.

Here is a web article on taking magnified photos of edges with an OX3 microscope. I'm not knowledgeable on this topic but found this through a google search. Thought it might be of interest to some folks.

You are awesome Jimmy! Great read with a cup of coffee.
M

Great posts above. I think newbs or even intermediate honers can find this all a bit confusing, because in one thread we're saying "you can't really speak about grit rating when it comes to naturals" and then five minutes later we're on another thread describing coticules as 8-10K or Tam O'Shanters as 6-8K or whatever. (At least I know I'm guilty of this.)

The way I see there are two main pieces of intelligence a grit rating communicates:

(A) the qualities of the edge a stone will impart to a razor
(B) the relationship of that stone to other stones in a working "progression."

We can and often do in a loose sort of way use ballpark grit ratings to talk about (A) with regards to natural stones. Experienced honers know that doing so verges on metaphor, because the actual size of the actual cutting particles may vary widely and wildly within a single stone, and as Bart and others have pointed out, there are other factors like how deep it cuts and so on that count for more in the resulting edge. But it's a useful enough metaphorical shorthand for communicating the fact that a coticule's finer than a Tam but not as fine as a Nakayama, and so on.

But these ballpark "grit ratings" for naturals really don't tell us jack about (B), and can in fact lead to a lot of confusion on this score. With any good synthetic range of hones, I know that ~1K will be good for bevel setting, that 4-6K will be good for intermediate work, and that 8-12K and above will be good for finishing. The same is simply not true of naturals. The fact that a black surgical Ark is rated around 5K does not mean it's a good intermediate step between bevel setting and finishing. (It's way too slow to be a good working hone for that purpose; that'd be like choosing an extremely remote town in the midwest, hundreds of miles off the interstate and reachable only by rural roads, as a "good place to pull over and get gas" on a cross-country trip, simply because it's in the middle of the map). Meanwhile, the belgian blue is a good intermediate hone, but really for reasons that have nothing to do with its so-called grit rating. It's good because its slurry is less aggressive and hence less dulling than yellow coticule slurry (even though coticule slurry is supposedly of a finer grit). So you can creep up on a fine edge with the blue+slurry and then finish it on the yellow without. Grit ratings don't tell you why the blue is a good lead-in stone for the coticule, and for that matter they sure as hell can't clarify why a coticule w/ slurry can be a pretty good bevel setter.

It is the characteristic behavior of this or that natural stone – not its grit rating – that will tell you how it might work in a progression. They are totally, totally unlike synthetics in this respect.

Every time I read a newbie (or even intermediate) honer saying something like "I'm thinking of getting a white Arkansas (~1200) for bevel-setting," or "I'm thinking of buying a Tam O'Shanter (6-8K) to use between my Belgian blue (4-6K) and my thuringian (10-12K)," or "the Chinese 12K will be a good bridge between my Norton 8K and my Shapton 16K," I think we haven't sufficiently considered the confusion we sow when we use grit numbers for naturals, even in a casual way.

Dylandog,

That is as the most spot on explanation of why grit ratings for naturals are just meaningless. I envy your talent for explaining something that I considered inexplicable when I wrote my post yesterday.

Bart.

Originally Posted by JimmyHAD

A blast from the past .... here are photos taken by Tim Zowada of various hones and the edges of various razors sharpened on those hones.

Here is a web article on taking magnified photos of edges with an OX3 microscope. I'm not knowledgeable on this topic but found this through a google search. Thought it might be of interest to some folks.

That's all well and good, but do we really know the x range of that camera?

Originally Posted by Bruce

That's all well and good, but do we really know the x range of that camera?

Tim said in the text that it was @ 200x if I'm not mistaken.

[just an intermission]

Excellent thread this, gentlemen, thank you all!

[/just an intermission]

im sure someone has a setup that is understandable
like i use x grit before the natural and if anything needed after
just to suggest a range of use to those who think of getting one

i think someone said they can start on a coti with slurry then blue and finish on the coti

anyone ever try a syntetic in the middle and find out at what range the coti is less effective then desired for instance?