True Grit II: A Chart for Deciphering Sharpening Gear

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Pure opinion: Buying sharpening stuff would be easier if manufacturers used microns to describe the particle size of the abrasive in each product.

While microns isn’t a perfect description, it’s a heck of a lot better than saying a stone is a “fine crystolon” when that stone is useful only for grinding away damage on a woodworking tool.

Woodworker Bert Bleckwenn recently created a chart that converts many sharpening products for woodworkers to microns and shared it with me. It’s an excellent and useful chart and is a good way to understand how coarse or fine your abrasives are.

Sharpening & Honing – Stones – Abrasives – Inventory – 050514

A couple of caveats: Natural products are difficult to rate this way. For example, novaculite is the abrasive found in Arkansas oilstones. These can be coarser or finer depending on the individual stone. And there are other factors with abrasives – too many to really write about here without creating a book.

So if you have problems with this chart, I ask only this: Make a better one and I’ll consider posting it, too.

When I sharpen, here are the micron sizes I use for each operation.

  1. Grinding. This is the rapid removal of material to repair an edge, reshape it or to shrink my secondary bevel. I like a particle size that is 50 microns or larger.
  1. Honing. When I have dulled an edge and need to recreate a new zero-radius intersection, I like an abrasive that is between 15 and 6 microns.
  1. Polishing. All abrasives smaller than 6 microns are polishing media in my eye. How far you polish is personal. I usually polish at about 3 microns and then finish at 1 micron or so.

Thanks to Bert for this chart. And thanks in advance to readers for not trying to turn this post into a fight over sharpening (that’s a hint).

— Christopher Schwarz

About Lost Art Press

Publisher of woodworking books and videos specializing in hand tool techniques.
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22 Responses to True Grit II: A Chart for Deciphering Sharpening Gear

  1. steveschafer says:

    Can we fight over “course” vs. “coarse?”

  2. Thanks to you and Bert for sharing! I was a bit annoyed when I received my Arkansas stones, and the manufacturer failed to identify which stone was which, from the standpoint of ‘course’, ‘medium fine’, and ‘xtra fine’. I was able to figure it out from the order and color of the stones. They do work mighty fine.

    Keep up the good work!

    Lynn

  3. Kevin says:

    Thanks for the chart, the difference in grit description is what pushed me to purchase DMT stuff, even on the Amazon page it states what micron each stone is. Coarse is 45, fine is 25, extra-fine is 9 and extra-extra-fine is 3.

  4. Rex Wenger says:

    My old eyes cannot read the chart. Is bert going to make chart available with larger print? Rex

  5. tombuno says:

    And then there is the occasional issue of diamond plate fineness being off even within same mfg. range. I have a full range of diamond stones where the extra fine is coarser than the fine.

  6. bobeaston says:

    Being that we like our woodworking ever more precise, can the next revision of this chart be in angstroms?

    Seriously though, THANKS for the chart!

  7. drewstout says:

    Lots of good information here. A few questions, though. Is the particle size the average or the maximum? Does anyone have any information on particle size distributions? There’s no way to get every single particle the exact same size, so the best you can hope for is a tight range of sizes. But the tighter that range, the higher the level of quality control you need (and therefore the higher the cost). For instance, I’m guessing that the cheaper sandpapers have a larger range of particle sizes for a given grit. It’s probably an academic argument, but I was curious.

    • That is one the many caveats to charts like these. The information is all stated particle size and is from the manufacturers or (in a very few instances) from outside sources.

      So we don’t know. I would guess that these are best-case particle sizes.

    • steveschafer says:

      There are different standards for measuring grit size and for allowable grit size distributions for different kinds of abrasives. In fact, that’s the major difference between CAMI-graded and FEPA-graded sandpapers (and explains why the two scales deviate at finer grits).

  8. One thing that threw me off in the past was I bought the Veritas honing compound thinking it would be a step up from my Shapton 8000 (listed as about 1.2 micron on the chart), since the honing compound was advertised as .5 micron. Yet no matter what I did it would dull my edge immediately even though the particles were in theory smaller. From reading more on it, I think there’s two things going on:

    1. Stropping rounds over the edge especially when using leather but also even if you use MDF
    2. The .5 micron particle are actually suspended in larger micron sized “filler” material, so in practice you never get a .5 effect

    Other folks have commented that the honing compound is in reality more like a 3k grit edge which I’d believe.

    So now I leave my 8k edge as-is, but use the strop just in between sharpening when I don’t have time to use my water stones.

  9. jonathanszczepanski says:

    Two posts in a row about two SAPFM members. SPAFM giving back!

  10. lignarium says:

    This is one of the reasons I love Shapton Stones. Every Stone has the size of the particle printed between the glass and the stone.

  11. tellis2365 says:

    A minor quibble. 3m has 2000 and 2500 sheets that are sold in the automotive section of WalMart. Anyone have an accurate mapping to microns?

  12. Jonathan says:

    There’s only one way to sharpen.

    Often.

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