Grit scales for sandpaper and waterstones.

The official definition of the grit levels of sandpaper goes something like this:
40-60 coarse 80-120 medium 280-320 extra fine 360-600 super fine
The highest number I've found is the 600.
But in several references to waterstones I've seen the numbers 1000 and higher, maybe even 3000. If this is on the same scale as above, it would imply that the waterstones are much finer than "super fine". Can this be right?
My question is: Is the same grit scale applied to waterstones and sandpaper or do waterstones have their own scale?
The reason I'm asking is because I'm considering trying to sharpen my tools with sandpaper (the Scary Sharp method).
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Here's a chart that explains all the grit numbers: http://www.nortonconsumer.com/pdfs/GenInfo2004.pdf
JeffB
Zaster Sap wrote:

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Mr. or Ms. Sap
    I use the scary sharp method.     The finest wet/dry paper I can find in this area is 1500 grit.     I think it is used for dulling car finishes before repainting.
    This works very well for softwoods and okay for oak or maple. It probably would not produce a sharp enough blade for the harder woods (which I have never used anyway).
    What bugs me about stones, besides the price, is that you have to do maintenance on your maintenance tools (flattening the stone). Sandpaper can just be thrown away.
Just my opinion Joe
On Tue, 15 Jun 2004 10:47:12 -0400, "Zaster Sap"

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1500 works just fine for sharpening edge tools for use with the harder woods. In fact, many folks I know, who produce excellent work, generally stop at 800.
I happened to run across an article in FWW written in the mid 90's by James Krenov, on hand plane tuning. He indicated that, although heresy by then- current dogma, he sharpened his planes with three levels of oil stones, and a little kerosene. His finest grade of stone was a hard Arkansas, if memory serves me. That's what I use on my kitchen knives.
My planes get taken to 800 with Scary Sharp, unless the project is at it's final stage. Then 1200. Maybe.
Last project with 'harder woods' was, in fact, a plane body, with a base plate of Jatoba. The one before that, Cocobolo. The plane blades were just fine at 1200.
Patriarch
"if it's good enough for Jim, well, then, ..."
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If you go to an automotive paint store you can find grits in excess of 2000 and these are for wet sanding fresh paint to make it look deep. Some of the best paint jobs are wet sanded.
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I understand waterstones and diamond stones do have different scales and they don't cross exactly.
I use scary sharp on my planes and they are sharp, it's easy to do. But the experts (jay greer, Steve Knight) say waterstones will get you sharper.
Alan
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Same grit will give you the same scratch size, which is what sharpening is about. Waterstones might get you there faster, powered waterstones faster still. Speed counts more as an end to a sharpening cycle than as a hone between cycles.
Stropping gives you the finest scratches, not honing. Not sure - meaningless anyway - what "grit" it is, but Chromium Oxide compound makes a fine strop, with powered strop more rapid than manual.

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Unfortunately, waterstone grits do not compare directly to sandpaper grits. Sandpaper can even be graded with different scales.
From <http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=shop&file=articles_244.shtml :
"There is little disagreement that one should sharpen to at least P800 (for comparison, a 1000 grit Japanese water stone equals FEPA P800 and CAMI 500 in abrasive sheets). Not everyone agrees how much beyond P800 is necessary. As a point of comparison, a 6000 grit Japanese water stone is equivalent to CAMI 1500 abrasive paper which is a third the particle size of FEPA P2000 paper. Some people recommend continuing to P2000 in abrasive paper and then stropping, while others stop at grits coarser than P2000 and then strop."
Somewhere out there are comparison charts between the stone grades, American sandpaper grades, and European sandpaper grades. I don't have time to track it down right now.
Barry
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You are, of course referring to the meaningless numbers, rather than the actual grit, I take it?
Same grit - same scratch, regardless of how produced. I think we get hung up an awful lot on the micrometer business, when we ought to be result oriented.
wrote:

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faster
<http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=shop&file=articles_24 4.shtml>:
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The 600+ grits are hiding at your local auto supply store in the paint section.
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Actually automotive paint stores carry grits in the 2000-4000 range. These grits really bring out the shine on a freshly paintesd surface.

I have an 8000 grit water stone. It'l put a mirror finish on a chisel.

No. they are all rated differently.

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As others have mentioned paint and automotive stores carry much higher grits than that. Also, Lee Valley has PSA-backed 3M microfinishing film in 15, 5 and 0.5 micron which are supposedly equivalent to 1000, 2500 and 9000 grits. I don't know if they are equivalent or not, but I do know that I've been using the film for several years now, and my edge-tools seem to be sharper and to hold an edge better than when I was just using plain old SiC wet-dry paper.
I attach the film to granite surface plates and keep it out on my old modified w*rkm*tt, so it's just a matter of taking a few steps over to the bench to touch up an edge.
There are also some other companies online that sell a variety of films, etc. Precision Surfaces International (http://www.psidragon.com /) is one I've dealt with, and there is another company that's even cheaper, but I can't seem to find their site right now.
Chuck Vance
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http://www.ketone.com /
carries 2000 grit!
Alex
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... sorry that is to say 2500 grit. Alex
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