What’s this Stropping Magic?

strop_IMG_5235

If you’ve read even a little bit of the sharpening information in “The Woodworker: The Charles H. Hayward Years,” you’ve probably noticed how much they discuss stropping.

We’ve had several questions from readers about this. Why do some people strop and some people don’t? Should we all be stropping? Is stropping outdated? Is it fayrie majik?

Stropping is simple. It’s the polishing of an edge with an abrasive that’s about 1 micron in size. Nothing more.

It’s the same as polishing an edge with a Japanese waterstone that is about #8,000 grit or #10,000 grit. Those stones have an abrasive particle that’s in the neighborhood of 1 micron in size.

(Don’t believe me? Here you can see the Lee Valley Honing Compound is rated for 0.5 micron. And here you can see a Shapton #30,000 grit stone is rated at 0.49 micron. In my experience, neither does a particularly better job than a 1 micron or 1.5 micron surface. Why? Because of the real world.)

So if you sharpen to #10,000 grit and then strop, I would argue that you are doing no harm, but you probably aren’t helping things much – other than extending your break from real work.

Why does stropping exist?

Until the introduction of fine waterstones, natural sharpening stones, such as oilstones, couldn’t polish an edge past a certain point – about #4,000 grit was typical (using the Japanese waterstone system for comparison). So the strop was the way to get the extra polish that makes the edge last a little longer.

Though I use Japanese waterstones a lot, I also have a strop. Why? For carving. With carving tools, I am constantly touching up the edge with a strop to keep the bevel shiny, smooth and keen. (Stoning odd shapes is a drag, so I try to put it off as long as possible.) A strop is an easier way to do this than having a wet waterstone at the bench. Also, a flexible piece of leather charged with honing compound makes it easy to polish up gouges and the like.

So strop. Or don’t. Just know that it’s part of a Western tool tradition and makes total sense with oilstones. With Japanese waterstones, the strop might be superfluous.

— Christopher Schwarz

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20 Responses to What’s this Stropping Magic?

  1. Damien says:

    I thought Lee Valley was also rated “300 mesh … the largest particle that would pass through a 300 mesh screen 169 times larger than .5 microns” (Andrew Johnston 2008) But yes I get nevertheless my shiniest results with green compound.

    • I don’t like to discuss religion… so I generally avoid this discussion on mesh/micron size. People who wish to go down this rabbit hole can start here: http://www3.telus.net/BrentBeach/Sharpen/Stropping.html#cont

      One of my “real world” caveats is that large particles of polishing compound tend to get pushed down into the strop bed, leaving the finer ones doing the work.

      I’ve compared many stropping compounds, including those by knife makers (aka total nutjobs) and diamond strop fluid (0.25 micron) in the shop (not with a magnifying apparatus).

      To the woodworker, the difference is insignificant.

      • Justin Meehan says:

        Thanks for the look into Hayward’s extensive discussion around stropping… Know it is a dark bunny hole for many when it comes to sharpening. This was an unbiased historical look into his perspective at the time. Appreciate the clarification.

      • colsdave says:

        Quite the rabbit hole. A partial précis:

        Some grits makes you sharper
        And some grits makes you dull
        And the grits that mother gives you
        Don’t do anything at all
        (Cribbed from Grace Slick)

  2. jfkriege says:

    I have recently been experimenting with stropping, and find it most useful between sharpening on stones. If I am paring something like dovetails, I can take a couple strokes on the strop and keep from going back to the stone as quickly.

    • miathet says:

      I have started doing this as well. It may be psychological but when I am taking a quick break I’ll run the chisel over the strop and it seems to cut better and and as said above doesn’t require sharpening so soon. It also lets me take a break so I work more carefully and not too fast.

  3. Mariano Kamp says:

    For stroping chisels. How thick should the leather be? 1/16 inch? Rough or smooth side up? I really hope to get thatanswer from you 🙂

  4. momist says:

    My strops are made from the leather of an old brief case, I’d guess more than 1/16″ thick. The outer surface was a bit beat up, but the inner surface still smooth and glazed with some finish. I sanded that off, and use that side to strop on. If you use a rough leather, you will catch it more with your blade and cut it up quicker, but it needs a little ‘tooth’ to take the compound. 240 grit abrasive worked for me.

  5. stevevoigt says:

    Chris, I have to strongly disagree with the statement that stropping is “the polishing of an edge with an abrasive that’s about 1 micron in size. Nothing more.” Traditional stropping is done with no abrasive at all; the purpose is simply to remove any bits of wire edge that didn’t come off on the finish stone.

    A basic problem in talking about stropping is that there are some drastically different definitions of what it is. Watch Larry Williams take a few gentle swipes on bare leather; then watch Paul Sellers hyperactively sharpen on leather charged with a thick layer of compound. These are totally different activities that both get called stropping (the latter shouldn’t, in my view, but that’s just my opinion).

    The approach you describe above is a very good one, but it’s not the traditional nor the only way to strop.

    Sorry for being “that guy” with the sharpening post. 😉

    • Steve,

      I should have been more clear in my entry. I’m discussing 20th century stropping from Hayward, which in many cases references a rouge or abrasive compound.

      Period stropping is something different, of course. And is more about the wire edge than anything.

      Every question I’ve ever gotten on stropping during the last 20 years has asked about modern methods: leather, compound and unicorn farts. So I admittedly have blinders on.

      Chris

  6. stevevoigt says:

    Thanks for the reply, Chris. That all makes sense.
    It is interesting that Hayward mostly talks about charged stropping. I’m looking forward to reading that…after I’m through with the Galbert book…

  7. nealm44 says:

    Perilously close to discussing whether to immerse or to sprinkle here. I personally strop between uses with chisels and gouges, regularly with my pocket knife, and after honing plane irons, etc. because when I was learning “stuff” from my grandfather that’s what he taught me to do. That likely made sense as we were using various oil stones and stropping may have taken the edge a bit more towards the elusive 0-degree. Using waterstones (or for moulding plane irons, abrasive film on a backing shaped to the blade) I very much doubt it really does any more than polish the blade a bit more. I do it anyway because it doesn’t “feel finished” until the stropping happens. My strops vary from my father’s barber strop (making it a very old strap indeed!) to scraps from a leather supply place glued to hardwood backing and then charged with stick compound. My brothers, our children, and now a couple of our grandchildren all use different stones, different strops, “scary sharp film”, and so on (one of us even examines his edge under a jeweler’s loupe) and you know what? All of the blades are very sharp indeed. When asked, I always say do whatever works — just pick a way and stay with it long enough that you’re practiced and confident and then branch out to something new if you want.

  8. The main issue with stropping arises when you put too much pressure on the tool as you drag it across the strop material. Because strops are often pliable means that downward pressure on the tool can cause you to inadvertently round-over the edge. Just use the weight of the tool itself and you will be OK.

  9. Deniseg says:

    I really like that chisel roll. What’s the source?

  10. amosswogger says:

    Even if the stropping and waterstone abraisives are the same size, there is one huge difference you left out: the strop is pliable (it has “give”). This slight amount of give allows you to reach the apex of the edge in an manner and angle that can’t be dulicated by the waterstone. As you well know the amount of “give” is a funtion of the hardness of the leather and (more importantly) the pressure exerted by the sharpener. Irregardless of micron size, this gives the strop an advantage over the waterstone in the final polishing allowing you to ensure the apex is polished, and very very slightly rounded. Of course the strop can be used incorrectly and edge rounded over too much, but this hazard is easily and quickly overcome with practice.

    Yes, I’ll admit it, I am one of those crazy knife fanactics!

  11. jwatriss says:

    I really liked using a strop when chopping dense hardwoods… White oak, Purple Heart…

    Yes, it dubs the edge. Fancy people can argue whether it constitutes a micro-bevel or a convex sharpening approach. Or a micro-convex bevel?

    Either way, stripping after every few cuts kept the edge keen, and the dubbed edge held up better through the job.

    Don’t believe the whiners. It’s not hard to grind off a dubbed edge and re-sharpen if you know how to take care of your tools.

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