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Thread: Basic Stropping Question

  1. #1
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    Basic Stropping Question

    Hi All,

    I am wanting to start doing stropping after using stones, and have no experience with it. I am planning to make a stropping set up.

    My questions are:

    Do you use the leather rough side up or smooth side up?. (I have vegetable tanned leather.)
    What stropping compound do you like, and where can it be obtained?
    Do you use more than one type of compound?

    Any advise would be appreciated.

    Thanks and regards,

    Stew

  2. #2
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    Ooh! I can do this actually!

    I strop all my knives and tools. Firm believer in it. The way I was taught was smooth side up, though I see people doing both. I believe smooth side up gives more consistency but that's subjective.

    To find the appropriate angle, lay the blade flat and slide it along the strop with the edge forward. Slowly raise the back of the blade until the edge catches. That's your angle. Any more and you'll round the edge, any less and you'll just be polishing behind the edge. With a big enough strop glued to a flat surface (hint: you should glue it to a flat piece of wood) you can use a honing guide and just drag the edge back.

    The amount of pressure is another matter of contention. I start out with moderate pressure and end with very light pressure. If you're using a honing guide to maintain the angle then use very light or no pressure. Some people use a lot of pressure, and I've seen people make that work but in that case you probably want your angle to be a little bit less than what you found above because the leather will conform more as you apply more pressure. Again, I just found that light pressure works better for me.

    Stropping compound--the most common is the green chromium oxide that is supposedly about 1 micron. I also have a black compound that is 3ish micron and a white that is supposedly 1/2 micron. I never go past the green, and I don't use the black too much honestly. I got mine from Bark River Knife and Tool but I think Lee Valley sells compound as well. I'd imagine most of it is the same if you get it from a reputable source. If you're using tougher steels you can use diamond paste. I've been just fine using regular compounds with O1 and A2 steels though.

    For applying the compound, heating up the leather and compound with a candle or lighter helps. You want a very think covering--as light as you can make it while making the strop a uniform color rather than just streaked with compound.

    This guy's videos demonstrate the concept pretty well:
    https://www.youtube.com/watch?v=3iMv...A#action=share

  3. #3
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    As to the argument of rough side or smooth side let us allow others to shoot flames on that one.

    What stropping compound do you like, and where can it be obtained?
    My current stropping compound is green chromium oxide. I have two different sticks from different sources that seem to be pretty much the same. One came with an Arkansas stone. It is sold by many suppliers including to the best of my memory Lee Valley.

    My other green stick of chromium oxide came from a lapidary supply shop. Rock hounds use it on wheels to polish stones. If there is a rock shop in your area you might want to go in. When they are not busy you may be surprised at how many things they have that can be useful in woodworking.

    After a blade has been brought to an edge on stones it is tested. Then it is tested again after stropping. This will let you know if the edge was improved or if it was dubbed in the stropping. It is now a rarity for me to dub a blade on a strop, but it happens when not paying attention. Most of the time it only takes three to five strokes on each side with the strop to bring up a smooth surface and remove a burr.

    For gouges and shaped blades I have various pieces of wood to use with softer leather to form to the shape of the tool.

    Of course as always, YMMV!!!.jpg

    jtk
    Last edited by Jim Koepke; 08-19-2017 at 2:25 PM. Reason: wording & For gouges and shaped blades
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  4. #4
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    Stew,

    I always strop my chip carving knives and they are (have to be!) extremely sharp. I use the smooth side of a piece of leather and use either a compound from a bar or a bit of the Tormek honing compound (a lot more expensive but easy to use and it stays in place.) My favorite stropping leather for these knives is pigskin glued onto a board but I use other kinds of leather with other tools, such as lathe spindle gouges and skews. You can get honing/stropping compound (and leather already glued to wood blocks) at carving shops. Amazon.com also carries several types.

    As mentioned, the angle has to be right. I use a light pressure.

    JKJ

  5. #5
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    Quote Originally Posted by Jim Koepke View Post
    My current stropping compound is green chromium oxide. I have two different sticks from different sources that seem to be pretty much the same. One came with an Arkansas stone. It is sold by many suppliers including to the best of my memory Lee Valley.
    Almost all of those "green sticks" come from a single manufacturer. I can't remember who it is, but Brent Beach tracked the source down a while back.

    I use the green stuff on irregularly shaped tools. I use it on the smooth side of leather (for convex tools) or wooden forms (concave). I also have some 0.5 um AlOxide paste that came with my Tormek. When examined under a scope it definitely leaves a finer surface than the green stuff, but I don't see much difference in bottom line results.

  6. #6
    Stropping is a very low tech technique. You shouldn't try to make it too complex. Many substrates work. Many compounds work too, some better or finer or faster. But you use it very sparingly and over time the grit breaks down anyway.

    So, what do I use? Leather from an old motorbike saddle bag. Rough side up. Compound is Autosol chrome polish. One tube will easilly last a few lifetimes. My choices were driven by availibility and cheapness.

  7. #7
    Quote Originally Posted by Kees Heiden View Post
    Stropping is a very low tech technique. You shouldn't try to make it too complex. Many substrates work. Many compounds work too, some better or finer or faster. But you use it very sparingly and over time the grit breaks down anyway.

    So, what do I use? Leather from an old motorbike saddle bag. Rough side up. Compound is Autosol chrome polish. One tube will easilly last a few lifetimes. My choices were driven by availibility and cheapness.
    Basically what Kees said. The same applies to honing as well, I read the current sharpening thread and shake my head in amazement at how difficult some folks make something simple, use an abrasive to get a burr, then a finer abrasive and a strop with a still finer abrasive to get rid of the burr. Go back to work, repeat as necessary. The whole process shouldn't take more than a minute or two.

    I will make a statement that I can't back up other than with observation: A stropped edge will stay working sharp longer than one straight off the finest stone. As always with any thing wood....YMMV.

    ken

  8. #8
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    Quote Originally Posted by ken hatch View Post
    I will make a statement that I can't back up other than with observation: A stropped edge will stay working sharp longer than one straight off the finest stone. As always with any thing wood....YMMV.
    My observation is the same, for woodturning tools in my case. For example, I use a 1200 grit CBN wheel on the Tormek to grind/sharpen my spindle gouges then hone/polish on the leather wheel then strop for a few seconds. The subjective result is a longer-lasting edge. I recently got an Edge On Up SharpCheck sharpness tester to try to put some numbers on this. I need to devise a reasonable test procedure for the lathe. It would be easier for a plane.

    JKJ

  9. #9
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    Quote Originally Posted by ken hatch View Post
    I will make a statement that I can't back up other than with observation: A stropped edge will stay working sharp longer than one straight off the finest stone. As always with any thing wood....YMMV.
    I think that it's safe to say that more refined edges last longer. Hard steels are brittle, and notches/striations tend to grow with use. One simplified way to think of this is that your goal in honing is to reduce those striations to a similar scale as the steel's own grain structure. Going finer than that doesn't help, since the steel will simply fracture on grain boundaries instead of on sharpening striations. As always there is more than one way to get there.

    With that in mind, the validity of your statement depends entirely on what your "finest stone" is. I see better edge life when I strop after using my Arkansas slipstones (Norton translucent for the most part), but if anything stropping makes things worse when I use it after my finest (10K+) bench stones.

    Quote Originally Posted by John K Jordan View Post
    My observation is the same, for woodturning tools in my case. For example, I use a 1200 grit CBN wheel on the Tormek to grind/sharpen my spindle gouges then hone/polish on the leather wheel then strop for a few seconds. The subjective result is a longer-lasting edge. I recently got an Edge On Up SharpCheck sharpness tester to try to put some numbers on this. I need to devise a reasonable test procedure for the lathe. It would be easier for a plane.
    A 1200 CBN wheel leaves pretty large and "sharp" striations (CBN is a pretty harsh abrasive), so I think that stropping is near-mandatory in your situation.
    Last edited by Patrick Chase; 08-20-2017 at 1:30 PM.

  10. #10
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    Quote Originally Posted by Patrick Chase View Post
    A 1200 CBN wheel leaves pretty large and "sharp" striations (CBN is a pretty harsh abrasive), so I think that stropping is near-mandatory in your situation.
    There are differing opinions on the need. With even a striated edge will cut wood well on the lathe. Most people, BTW, use turning tools directly off a 120 or 220 grit wheel and many never remove the burr. The spinning wood takes the burr off the edge in seconds but the rough edge still cuts the wood. I used the Tormek water wheel for years before going to a 600 grit CBN which I found too coarse, even though it was finer than what most use. There seem to be relatively few woodturners stropping although some do dress an edge with a diamond hone.

    For some tools (roughing gouges, bowl gouges, parting tools) I skip the polishing but still hone/strop to knock off the grinding bur regardless of which grit I use. However, I far prefer a mirror polished edge on my spindle gouges (and sometimes the skews) especially when working with certain woods like hard, fine-grained woods (e.g., dogwood, cocobolo, ebony). The scratches on the blade edge are transferred directly to the wood. I find that with a polished/stropped edge and good tool control I can get clean surfaces, at least on smaller things, that need little or no sanding.

    But the less-than-objective observation that the stropped edge cuts better and lasts longer is the biggest reason I do it. BTW, in their literature Tormek makes the same claim about edge life.

    JKJ

  11. #11
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    My strop is rough leather on a wooden board that I bought from Paul Sellers at Homestead Heritage many years ago.
    It is charged with green compound. Check Amazon.

  12. #12
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    Quote Originally Posted by John K Jordan View Post
    There are differing opinions on the need. With even a striated edge will cut wood well on the lathe. Most people, BTW, use turning tools directly off a 120 or 220 grit wheel and many never remove the burr. The spinning wood takes the burr off the edge in seconds but the rough edge still cuts the wood.
    Ah, I was thinking in terms of non-spinning woodworking when I made that comment. I don't have significant firsthand knowledge of turning so I'll leave it there.

  13. #13
    I have used a clean strop, smooth side up, since 1965. I tried some polishing powders around forty years ago, but I prefer clean and dry.

    I can't recall seeing the green bar in a professional shop. I think if I were to use an abrasive on the strop I would use powder. The wax bars are designed for a buffing wheel.

  14. #14
    Strop for carving tools, knives, and straight razors - either Warren's clean strop for stuff coming off a hard black arkansas or the Tormek stuff in a tube on the power strop for carving tools. Never on chisel or plane blades, where my preference is for the edge I get off the stone. I religiously stropped for decades before bagging it after moving from oil stones to diamond/waterstones back in the 1990's.

  15. #15
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    I use green stropping compound with leather smooth side up, glued to a board. I am of the opinion that rough side up will give you some rounding or dubbing of the edge.
    Life's too short to use old sandpaper.

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