Thread: Finer Than 8000 Grit Stones?

There are a large number of people who swear by the Chosera 10k stone... It is reputed to be one of the finest....

With the way water stones work - there may not be much benefit of going from 8k to 10k...

Our own Rob Streeper is in the throwes of a huge chisel test... His results at this point are pointing towards diminished returns in performance on wood past 5k... But if it makes you happy to polish your edges out to atom splitting levels - by all means, have at it...

I have the 13K stone that Stu (Tools From Japan) sells in the set he recommends and the seat of the pants feeling is that there is a worthwhile difference between the 8k & the 13K in that set. Is it necessary? most probably not but I spent money buying it so I have convinced myself it is worth using.

A couple of sides to the coin Luke. Conventional wisdom has it that the sharper it is the longer it stays sharp.

OTOH Rob's tests seem to show that the extra sharpness goes too fast to be worthwhile.

Both of those arguments are probably largely dependent on what wood you are working. An abrasive timber will no doubt knock any degree of sharpness off so it's probably not worthwhile going up too high to save considerable time at the stones (of course the particular piece of timber may have grain that demands a sharper blade).

The easiest, safest, calmest thing to do? Stay out of any discussions on sharpness, bed angles, primary angles, microbevels, which waterstones to use (or NOT ), which plane is best, what plane should I buy, etc etc etc etc etc etc. You'll get a helluva lot more work done without the angst or observing prat-like behaviour.....

That is a good point about the wood you are working and what you are trying to do....

For example - if you are shaving spruce - the ultra sharp edge will allow you to do some seriously beautiful work leaving an ultra smooth and glassy surface that is unmatched by any other tool - especially on end grain... And spongy styrofoam with hard grain line spruce end grain is tricky to cut smoothly without crushing... But if you aren't super careful - you will knock the ultra sharp edge right off the chisel when it flies through the styrofoam grain and hits the hard grain line....

On the other hand - something really hard and abrasive will dull the ultra sharp edge fairly fast but it will leave an edge that still lasts a good long time... In this case - you may not see any benefit of going up...

So far I've seen marginal increases in sharpness past 5000 grit. Most of the chisels I've tested do gain a little but like truckjohn wrote above that extra smidgen goes away pretty quickly. Awfully hard to realize any increase in sharpness beyond 10-12 k or so. If you have a really good and stable jig you can get a tiny bit but it's lost quickly.

Interesting and as yet unexplained observation is that some chisels, like the LN bevel edges and Craftsman appear to get sharper coming right off of the stone, especially in soft wood.

Very hard to have "seen" any kind of an edge without a Scanning Electron Microscope for your eyes.
Leonard Lee is the Myth Buster here. Look at the micrographs in his book. Canada's National Engineering and Research Council = your CSIRO.
1. Bevel angle. He claims that you need enough steel behind the edge to support it in service.
I run everything from 30* down to 12*. The tool edge fits the job. No argument.
2. Test and test. For our very soft western red cedar, I'm carving an over-ripe tomato.
I go to 1,500 grit and hone with CrOx/AlOx for success.

Australian woods are far more diverse and far harder that anything I encounter.
Pick a bevel angle and select a stopping grit. 47,000 grit won't help you at all
if it is your intention to use 320 grit sandpaper at the end of the day.
You ought to be using scrapers to cut the surface.

Originally Posted by Robson Valley

Very hard to have "seen" any kind of an edge without a Scanning Electron Microscope for your eyes.

When I wrote "seen" above I meant changes in numerical measurements of edge performance. SEM pictures would be a nice complement and may provide insight into failure mechanisms.

Originally Posted by Luke Maddux

I had someone adamantly argue with me on another forum that the difference between an edge honed at 8000 and an edge honed at 16000 grit on waterstones was significantly different.

I'm reluctant to believe this, but I thought I would get some other opinions. The chances of me buying a super high grit stone are low, but I'm also the type of person who likes to experiment and be able to comment on a topic, so I'm at least open to hearing about it.

Interested in any feedback.

Hi Luke

I THINK the consensus is that not all water stones finer than 8000 are equal.
I recall some commentary that a Shapton 12000 stone does not produce an edge as good as that from a Sigma stone of equivalent grit -- I suspect that at higher grits, the binder is almost as important as the size of abrasive particle.

Leonard Lee's 2 pages of SEM pictures changed how I sharpen and finish edges for carving in very soft woods such as western red cedar and yellow cedar.
Steels are not crystalline. The best you will ever do is shred the edge. The total included bevel angle probably matters just as much.
I think that it's entirely practical to switch over the Oxide honing compounds for any excursions needed above 2,000 grit stones.

Steels have a crystalline structure. That doesn't mean that you'll see crystals under a scope (you won't, the crystals are bonded together).

I have experimented with stones more than anyone I know, and at a cost (I haven't kept them all) greater than anyone I've ever met (aside from someone collecting rare versions of the same thing - like hatanaka stones).

The difference in an edge above the 8k level is very practical for shaving. For woodworking, it's nice for a beginner because beginners really don't have any hand/brain subtlety that you learn from sharpening for a long time. That subtlety allows you at adjust so that you get a durable edge as well as a sharp one, and to make sure your edge is finished and free of foil.

I don't disagree with the comment above about going to oxide compounds if you like to do that, but I like a stone better. I'm too far down the road to think about what I like or don't like about various synthetic stones, as I generally finish with natural stones instead (and quickly - I don't like the maintenance that synthetic stones need if they are in that area of fineness. Natural stones generally don't need it, and I like their cutting qualities better).

Last year (or early this year), I undertook an effort to sharpen a bunch of ashley iles chisels with various abrasives, starting at the 8k stone sold as "kitayama". I didn't measure edge thickness, just refinement by eye. I was surprised to see that autosol on hard leather was much cleaner than the 8k stones, despite the abrasive supposedly being similar in size.

Short answer after the long answer, I don't think stones above 8k will give you anything in terms of work results or surface finish, but if you like them, buy one and use it. If you're going for something practical, take up straight razor shaving to learn the value of stropping to remove the wire edge. Not stropping to use compound, but to improve an edge by making sure that it's defect free and without foil.

Brent beach has a page concluding that stropping is useless, but he doesn't know anything about stropping. He's comparing honing with films to honing with compounds on leather. If stropping didn't do anything, barbers wouldn't waste their time with it (or wouldn't have in the days of straight razor shaving).

Separate side comment, Luke. I currently have stones varying in value from $1 to $800 (US). One of my favorite finishing rigs is japanese natural whetstone powder on jasper. The powder was free for me because I sell some natural stones and need to lap them (thus, I end up with a bunch of powder). The jasper cost me $10, and I'm assuming there is some sort of equivalent in australia (not glass or something like that, but jasper - I haven't tried glass). the powder on the hard jasper is very aggressive, works extremely well with WD 40, and it will finish anything very finely and very quickly with no chance of damage - no matter what direction you hone - to the base stone.

I didn't organize myself and remember where i posted the pictures, but I'm sure I could take more. I don't think people learn much from pictures, though - they learn from experience and the need to find a result.

1. The scanning electron microscope pictures showed me how far and how fine grit particle sizes are practical. Not to be ignored.
The steel edges are smeared and shredded, no matter what was done in the sharpening process. Most disappointing.

2. It isn't useful to ignore the edge quality in service where major differences in woods are encountered. A "good" edge for hard woods
is of little value in carving soft woods. Like the edge you need to slice an over ripe tomato.

My sharpening regime goes 2000 (Sigma I think), 8000, 13000 (Shapton?), but a lot of the time I stop at the 8000. Might go the 13000 on chisels from time to time, especially for use on softer timbers (e.g. dovetailing in hoop pine). Starting point is a hollow grind off a CBN wheel, so I'm only working on the microbevel with stones. Plane blades are rarely taken past 8000, with the possible exception of a bevel up smoother.

As well as an SEM picture of the freshly sharpened blade (I have the Leonard Lee book), proponents of ultra-fine stones should be shown another SEM of the edge taken after about 10 strokes with a plane on even a moderately hard Aussie timber....it ain't pretty

Mr Brush. A question if I may.
I agree that fine edges must crumple badly in Australian woods.
You have 10X the challenge that I have.

Do you think that a slightly steeper bevel, say going from 25* to 35* would put
more steel for support behind the edge and thus reduce the crushing?