Over on my earlier thread about hand planes, you all stressed the importance of blade sharpness in plane irons, and Jay got me to thinking of my abrasives in terms of microns. And this makes so much sense and really levels the playing field as far as abrasives are concerned.

I've done some research and found some discrepancy in these grit/micron charts.

1) I use Norton waterstones, 1000x, 4000x, 8000x. After Jay mentioned that he goes down to 0.5 microns with his plane irons, I was a bit concerned that my Norton 8000x wasn't giving me the best edge I could get, considering I will be planing white oak timbers. Nortons site lists the 8000x as 3 microns, while other charts list it as 1.2 microns. I see that some charts go by average particle size in the stone, and some go by the largest particle size in the stone. Any thoughts there on potentially clearing that up?

2) Also, I read where you can calculate approx. micron size by dividing 12,500 by the JIS grit standard (Japanese Industrial Standard) listed on abrasives. Any validity to this?

3) I recently bought a Sigma Power Select II ceramic 13,000x stone, but Lee Valley does not list it in microns. I've seen others say it is between 0.5 and 0.78. Sigma's 10,000x is listed at 1.5 microns, so I'm thinking the 13,000x ought to be under 1.0. Anybody have this finishing stone and know it's particle size in microns?

4) So my last question (ya right). Assuming my Norton 8000x really is 3 microns, is it too big of a jump to go to the Sigma 13,000x? Should I get another stone to fill that gap?

On a separate note, like some others here, I've had some down economic times recently and had to let my Guild membership lapse. But I was so impressed with the very helpful responses to my plane thread that I have since re-joined and am once again a proud Guild member. This forum has been an incredible source of info for me over the years, it's the very least I can do to give back. Thanks to all.

Ron:
Thanks for your membership.

Jim Rogers

You bet Jim!
Hope you and Tom are doing great!!

I don't have an answer to your question. I'd say give it a try. As long as you clean the iron of any grit before moving to a finer stone, you can't really hurt anything. I think green stropping compound is .4 micron. I go to an 8000x King waterstone. That seems to be just fine. Stropping would be a little bit better, but I don't see it as being any advantage. Jay might be referring to Japanese plane irons. They could be harder, and might benefit from a finer edge.

Thanks for renewing. Sometimes it comes at a tough time for me, but I find a way.

Here is a link to a chart of grit sizes

http://www.toolsfromjapan.com/store/index.php?main_page=page&id=13&chapter=5

Sharpening can become a marital art of extremes, a 13,000 polishing stone is getting close to ultimate, some people use mdf charged with buffing compound as a hard strop to avoid a comparitavely soft leather strop in hopes to prevent rounding.

I am a big fan of finishing with compound, green or gray. It really gives it a shine, and fun to see the fine thread worked off the blade.