Thread: Looking for Micron Ratings for Sigma Stones

Others here know more about this and I don't have my tables with me.

Google for abrasive rating/conversion tables.

I understand from NeilS that JIS includes several rating systems just to make things more complex.

Stu from Tools from Japan, Japanese woodworking tools direct from Japan. is a member here and can advise.

HTH.

Sorry Russell. I would have made notes if I had ever seen such information.
I believe that I can guesstimate oil stone surfaces against sandpapers with my fingertips and my eyes shut. Otherwise, it's an issue of tool surface qualities after the "grind."

I am coming around to the notion that these companies, for whatever reasons, don't feel the need to reveal or be honest with customers regarding grit size/ stone composition.

In any event, I'm getting carving sharp edges on all 9 of my crooked knives off 1500 W&D grit (go easy/dry) then honing with chrome green on the finest crackerbox cardboard that Nabisco can provide.

Cheers guys.

The reason I asked incidentally is that I've heard the Sigma 6000 is finer than the Norton 8000, and on the razor forums they often say a Norton 8000 is a reasonable beginners razor hone. So, I'm thinking my Sigma 6000 could save me any reinvestment...

Easily sorted ... scrape it and see

I use the Sigma PS II 6000 as the last stone on my JP knives and it works well enough for me. But I haven't tried those edges on my face fungus.

Originally Posted by Robson Valley

Sorry Russell. I would have made notes if I had ever seen such information.
I believe that I can guesstimate oil stone surfaces against sandpapers with my fingertips and my eyes shut. Otherwise, it's an issue of tool surface qualities after the "grind."

I am coming around to the notion that these companies, for whatever reasons, don't feel the need to reveal or be honest with customers regarding grit size/ stone composition.

In any event, I'm getting carving sharp edges on all 9 of my crooked knives off 1500 W&D grit (go easy/dry) then honing with chrome green on the finest crackerbox cardboard that Nabisco can provide.

You'd be right with the bold, kind of.

Abrasive grit size comparison chart.

Unfortunately, this chart is not obvious in where it's lurking...

The Sigma Power stones conform to the JIS 6001:1998 standard, as far as that standard goes (#8000 only), and extrapolated/calculated beyond that.

Note the Sigma Power #6000 stone does have white aluminium oxide abrasive particles of 2±0.4µm with a relatively durable resinoid binder and the Norton gives us only 3µm with no range, no abrasive material and no binder explanation.


Stu.

I played with some emery abrasive stick on MDF discs on the lathe by way of one attempt at polishing out milling marks.

Can't recall the grit rating, maybe #600 acc to some standard, but the variation was plus/minus 200!

So Stu, AlOx particles are sposed to fracture. Do they get smaller to any significant degree? Ie. emulate a natural stone?

Thanks again, Stu.

I couldn't open the link for some reason most likely connected with my internet connection, but the info you put in your post was exactly what I was looking for.

As a side note, I have found the Sigma 6000 to be great to use as a beginner, and can get good edges even when freehanding microbevels (with the rounding of the edge that that most likely entails...).

Originally Posted by rsser

So Stu, AlOx particles are sposed to fracture. Do they get smaller to any significant degree? Ie. emulate a natural stone?

Actually, AlOx tends to blunt, not fracture. SiC is harder and more brittle, so it will tend to fracture and reduce in size and you can make them deliver more of a polish if you're careful, but the polish is often visual, as the smaller particles are still sharp and will leave sharp scratches/striations in the steel.

AlOx, again if you're careful will tend to polish when it's worn, but the polish has more burnishing, similar to a natural stone, as the particles are hard, but blunted. Gives a better edge and closer to a natural at the micro level, but because the particles tend to be of similar size, the blunted ones also tend to be smaller (as they're missing their edges) and the burnishing effect is somewhat limited.

A natural stone has some particles hard enough to cut, some not hard enough to cut but harder than the steel and some particles that cannot cut the steel at all.

There's more to it than that, but I'm not yet sure enough to tell anyone what I think happens. In short, a natural stone is a different animal entirely, and no synthetic stone works the same way as a good natural. But a good synthetic always works, whereas a natural doesn't always work...

Stu.

Excuse my ignorance, but why does it matter? If you get the edge you need/want with the stones you have, the micron ratings and physical properties of the stone seem, to my mind, to be irrelevant.

As an aside, I finish my blades on a 12000 Shapton; not because it ends up sharper, I just like them shiny

That's a valid statement! It can be helpful to know the grit system even though it is a bit arbitrary. Each stone, tool and user will have a different feel when you get high in the grit range. It is useful to know the grit when your comparing stones and grades as you skill and style changes.

Originally Posted by elanjacobs

Excuse my ignorance, but why does it matter? If you get the edge you need/want with the stones you have, the micron ratings and physical properties of the stone seem, to my mind, to be irrelevant.

As an aside, I finish my blades on a 12000 Shapton; not because it ends up sharper, I just like them shiny

Why the #12000? Why not a King #1200? After all, the 'grit' and 'physical properties' are irrelevant...

A lot of folks do have stones, but aren't sure if what they have is what they want/need. The grit rating gives an idea of what the stone 'should' do, as in coarse/medium/fine and the composition of the stone and it's abrasive type can give an idea of how the stone should behave in use. By knowing a little about that, you can look at a new stone and maybe work out whether it's for you or see how what you have compares to other stones.

It's not that important if you're content with what you have, but it is somewhat important as a basis for comparison if you're not that happy or are looking to replace a worn or damaged stone.


It really depends on the person asking/answering the question. Some are content to be blissfully ignorant and others are OCD on the minutiae, but most fall somewhere between the two extremes.


Stu.

Knowing the grit and brand can be helpful when your learning from someone or sharing your system with others.

Originally Posted by Schtoo

Why the #12000? Why not a King #1200? After all, the 'grit' and 'physical properties' are irrelevant...

A lot of folks do have stones, but aren't sure if what they have is what they want/need. The grit rating gives an idea of what the stone 'should' do, as in coarse/medium/fine and the composition of the stone and it's abrasive type can give an idea of how the stone should behave in use. By knowing a little about that, you can look at a new stone and maybe work out whether it's for you or see how what you have compares to other stones.

It's not that important if you're content with what you have, but it is somewhat important as a basis for comparison if you're not that happy or are looking to replace a worn or damaged stone.


It really depends on the person asking/answering the question. Some are content to be blissfully ignorant and others are OCD on the minutiae, but most fall somewhere between the two extremes.


Stu.

I said micron ratings, not grit - I know that the higher grit numbers are finer stones and that it is neccesary to label them as such. What I meant by my comment was that I don't see how it matters whether a 6000 grit stone is 4 micron or 3 micron or 17 micron.

Originally Posted by elanjacobs

I said micron ratings, not grit - I know that the higher grit numbers are finer stones and that it is neccesary to label them as such. What I meant by my comment was that I don't see how it matters whether a 6000 grit stone is 4 micron or 3 micron or 17 micron.

Because an abrasive particle size of x micron is an absolute value, whereas 'grit' depends on who decided what grit was what. There are several scales, and to be honest, using the 'grit' of a stone for comparison is pretty much useless unless everyone is using the same scale.

Which they don't.

(But most of the Japanese makers use the current JIS standard. Shapton doesn't, nor does Norton. Norton have an excuse, as they're using a US based standard.)

And to convert grit from whichever standard used, you need to know what the particle size is, in micron.

That's why it can be important.

Or not.

Not everyone cares, and that's ok.

Stu.