Tried different approaches to stropping

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maximus83

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Nov 7, 2011
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I've been experimenting to compare different methods of stropping to see which I like, and what kind of different results they get on the knives I own. This is not an attempt to be comprehensive. Just listing things I tried for discussion. I'm using the word strop somewhat loosely to refer to any kind of final stage edge refinement, whether traditional stropping or not. Where the main goal is final edge alignment or improvement of the cutting performance.

Stropping approaches tried so far:
  1. Firm leather backed by wood, without compound.
  2. Suede leather backed by wood, with compound (I use Tormek 8K).
  3. Plain cardboard.
  4. Plain balsa wood.
  5. Balsa wood with compound.
  6. Spyderco Sharpmaker UF ceramic rods. Light strokes, same as sharpening angle.
  7. Clean damp high grit AlOx stone with light, edge-leading strokes. Same as sharpening angle.
  8. Clean damp high grit AlOx stone with light, edge-trailing strokes. Slightly higher than sharpening angle.
  9. Computer paper wrapped around a coarse bench stone, with compound. Same as sharpening angle.
  10. Basswood, lightly sanded, with compound. Strokes slightly higher than sharpening angle.

I found that all worked in some sense. All took an edge that was sharp from the stones, and made it perform better in certain kinds of cutting tests. In some cases, stropping made the edge do better in some cutting tests, and worse in others. Example: a well stropped kitchen knife lost some toothiness and did better in push cuts but worse in pull cuts.

A few unscientific observations:
  • Stropping on material with "give", like balsa or leather, does indeed cause some natural convexing or rounding of the edge. And that may not be a problem, but it does happen.
  • Stropping on hard materials does help avoid the rounding, if you care.
  • For all non-stone methods of stropping I tried, using compound generally got better results than not using it. I suspect because it helped with final burr removal?
  • Of all methods tried, methods 7 - 10 seemed to get the best results (in no particular order).
  • Of all these methods, the two I preferred the most were 7 and 10. 7, because it uses the same sharpening motion I am accustomed to, which makes it easier to hold a consistent angle. And it does not require any additional gear, or compound. 10, because I found the stropping motion easy and repeatable on the hardwood block, and it seemed to get the best overall edge performance of any stropping method I tried.
  • When I use a stone-based approach, I cannot get QUITE the final level of edge performance as say Basswood + compound. But I found that the practical difference in performance, for me, was so minimal that I'm tempted to skip traditional stropping altogether and just use stone finishing approaches most of the time.
 
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Reminds me of me many moons ago. I used to have bricks and bricks of red/white/green/black compound. Kangaroo, horse butt, hanging, et al. All trashed. These days, a single edge-trailing pass per side of the final apexing run is all I do. Maybe two or four per side at most. Keep up the good work, maximus83 :) .
 
I noticed one missing, firm leather backed by wood with compound. Thats my preference for stropping. Usually in between sharpenings. Sometimes I will strop on a very fine ceramic stone at the sharpening angle too.
 
I'd suggest, on the basswood or any other hard strop, keep your angle as low as possible, just 'kissing the cheeks' of the apex. Raising the angle above the sharpening angle will quickly widen or round the apex a little bit, when abrasive compound is used. It'll produce what looks essentially like a convexed microbevel on the edge. So, in any stropping with compound, keep the angle flush on hard strops of wood, and even a bit lower on compressible substrates like leather, paper, cardboard, fabric (denim, linen), and even on balsa wood. The edges will stay crisper for it.

Raising the angle is OK on bare strops, as they don't pose the same risk of abrasively rounding off the apex; instead, they do better at just breaking a weakened burr off the apex. With abrasive compound on a strop, all you want to do is thin the burrs to an extent they'll just tear away on their own, without needing to break them away by raising the angle.


David
 
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Obsessed with Edges said:
I'd suggest, on the basswood or any other hard strop, keep your angle as low as possible, just 'kissing the cheeks' of the apex. Raising the angle above the sharpening angle will quickly widen or round the apex a little bit, when abrasive compound is used. It'll produce what looks essentially like a convexed microbevel on the edge. So, in any stropping with compound, keep the angle flush on hard strops of wood, and even a bit lower on compressible substrates like leather, paper, cardboard, fabric (denim, linen), and even on balsa wood. The edges will stay crisper for it.

Raising the angle is OK on bare strops, as they don't pose the same risk of abrasively rounding off the apex; instead, they do better at just breaking a weakened burr off the apex. With abrasive compound on a strop, all you want to do is thin the burrs to an extent they'll just tear away on their own, without needing to break them away by raising the angle.


David
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Ok that is plausible on the angles.

In your thinking, is the compound even adding anything? It seems to improve cutting performance SLIGHTLY to me versus not using, and I assume this is because it is enabling some very light honing on the edge.
 
adamlau said:
Reminds me of me many moons ago. I used to have bricks and bricks of red/white/green/black compound. Kangaroo, horse butt, hanging, et al. All trashed. These days, a single edge-trailing pass per side of the final apexing run is all I do. Maybe two or four per side at most. Keep up the good work, maximus83 :) .
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I've been doing traditional stropping for years, mainly on plain leather, or on improvised things like cardboard. Recently I've seen such a diversity of approaches in the forum, I decided to play around with a bunch of them and see how they differ in results. I wish I had time to do a bunch of rigorous cutting tasks, document everything, photos, the whole 9 yards. Sadly, with my job, I don't. :) What I confirmed for myself above, is kind of what my hunch was. That stropping makes a difference, and some materials do better than others, but for the kinds of cutting tasks I do, stropping only makes a small incremental difference. Usually not worth the bother--in my case. I plan to just experiment with different techniques for finishing directly on a high grit stone, and eliminate the separate stropping step altogether.

I can see a plausible argument being made: But how about MAINTAINING your edge? Don't you want to keep your knives sharp while removing as little metal as possible, and without having to get out all your sharpening gear?

Ok, I'll admit that's an interesting counterpoint that I'm thinking about. :)
 
I don't know that I would consider #7 as stropping. But all of these should work to some degree. I usually go with the same as 115Italian's method. I have also stropped on the edge of a thick book's pages with good results. DM
 
David Martin said:
I don't know that I would consider #7 as stropping. But all of these should work to some degree. I usually go with the same as 115Italian's method. I have also stropped on the edge of a thick book's pages with good results. DM
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Right. I admitted I was using 'strop' rather loosely in this post. In your thinking, is it only stropping if you're doing edge TRAILING strokes on some material?

Also, do you find that using compound makes little or no significant difference? I've found that any stropping method, with or without compound, on almost any reasonable material, can work. So improvised stropping methods can work too: on your hand, on the thigh of your jeans, on bottom of a coffee cup (I've done all those too :-)). But I did find that once you've decided to strop and you have the materials at hand, the compound did make a slight but noticeable difference in results.
 
83, glad your thinking about this. I am moving toward the notion that some here have written on about 'not stropping'. Meaning why strop,
when you have just sharpened the edge. Remove the burr on the stone and your done. Then use stropping as a up keep on your edge. To prevent taking it to the stone. DM
 
maximus83 said:
Ok that is plausible on the angles.

In your thinking, is the compound even adding anything? It seems to improve cutting performance SLIGHTLY to me versus not using, and I assume this is because it is enabling some very light honing on the edge.
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Depending on the compound used, the steel being honed/stropped, and the held angle, it could be adding a lot, or not much, or even make things worse. If the compound is an aggressive polisher relative to the steel being worked (i.e., if it handles the steel's alloy & carbides effectively), AND if the held angle is good, there could be a lot of improvement. As an example, something like white rouge (aluminum oxide) compound used on 420HC, VG-10 (both prone to stiff, tenacious burrs) could add a lot to an edge in burr cleanup, sharpness and polish, and could do it very quickly. If the held angle is too high though, it could also very quickly round off the apex. Lots of variables to play with, and any one of them could make a big change, either good or bad.


David
 
David Martin said:
83, glad your thinking about this. I am moving toward the notion that some here have written on about 'not stropping'. Meaning why strop,
when you have just sharpened the edge. Remove the burr on the stone and your done. Then use stropping as a up keep on your edge. To prevent taking it to the stone. DM
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Exactly. I would gladly still strop in any case where I feel like it's giving some significant advantage over stone sharpening, for the effort invested. In my testing up to this point, I'm just not seeing it being a game changer, based on the way I use my knives. The *only* argument for stropping I'm still thinking about is the one I listed above: the "use it to maintain your edge without removing metal" argument. However.....I can imagine that with REALLY REALLY light edge-leading or edge-trailing strokes on a fine grit damp stone, you can achieve very similar results with very little metal removal. That's what I'm going to be experimenting with going forward.
 
Stropping motion on the top edge of a car door window works good too. I do that a lot at work. People look at me like Im crazy but...
 
Always fun to experiment and find out for yourself what works best. I've settled on two primary stropping approaches. A firm leather with green polishing compound applied to it, and a balsa strop with 1 micron diamond compound. Those two are "good enough" for me, both for final steps in normal sharpening and as a quick retouch between sharpenings.
 
Geez, I got awesome results tonight on probably the crappiest $5 paring knife in my wife's entire set. That blade looked like a saw blade there were so many chunks out of it. :-) I should've taken 'before' pictures.

Did this progression (profiled to about 12 dps, no micro). About 20 minutes to sharpen with most of it cleaning up the dinged up edge during profiling:

150 grit cheap diamond stone > Arctic Fox 400 > Ptarmigan (5 light backhoning strokes per side on damp stone, same as sharpening angle, in lieu of stropping)

This got fantastic results. Not just shaved arm hair but tree-topped it, effortless push-cuts through paper. The AF + Ptarmigan is a killer, killer sharpening combination.

Backhoning a few strokes on the damp Ptarmigan is an excellent replacement for stropping.
 
maximus83 said:
I can see a plausible argument being made: But how about MAINTAINING your edge? Don't you want to keep your knives sharp while removing as little metal as possible, and without having to get out all your sharpening gear?
Click to expand...
That is why I rack a few select stones next to the sink on the kitchen counter. The process of retrieving a stone, splashing it and touching up a micro can be measured in seconds. Perhaps a minute or two at most including cleanup.
 
maximus83 said:
Geez, I got awesome results tonight on probably the crappiest $5 paring knife in my wife's entire set. That blade looked like a saw blade there were so many chunks out of it. :) I should've taken 'before' pictures.

Did this progression (profiled to about 12 dps, no micro). About 20 minutes to sharpen with most of it cleaning up the dinged up edge during profiling:

150 grit cheap diamond stone > Arctic Fox 400 > Ptarmigan (5 light backhoning strokes per side on damp stone, same as sharpening angle, in lieu of stropping)

This got fantastic results. Not just shaved arm hair but tree-topped it, effortless push-cuts through paper. The AF + Ptarmigan is a killer, killer sharpening combination.

Backhoning a few strokes on the damp Ptarmigan is an excellent replacement for stropping.
Click to expand...


Backhoning on polishing grade waterstones is a solid way to go. You can also use a few scrub passes and then finish with a couple of backhone passes. Either way can be one of the most effective finishers.
 
adamlau said:
That is why I rack a few select stones next to the sink on the kitchen counter. The process of retrieving a stone, splashing it and touching up a micro can be measured in seconds. Perhaps a minute or two at most including cleanup.
Click to expand...

There you go--just eliminated my last reason for a separate stropping step when sharpening at home. :-) I'm not convinced that a small number of light edge-trailing strokes on a super fine grit actually REMOVE much more metal than traditional stropping, either.

I almost think that stropping is something I would keep doing in "improvised sharpening" situations, like when I'm backpacking to maintain an edge without sharpening. But not when at home and have the luxury of a nice setup of stones to use.
 
Ok, I like this too. ^ I think (light) back honing doesn't remove much metal as well. Plus, it can really tune up an edge. DM
 
For me, hard-backed stropping is one of the best ways to go. I find it to remove less steel and maintain geometry plenty close enough to reset on a hard stone from time to time without removing any more steel than a blown out microbevel, maybe less. The lifespan of my knives has increased considerably since I adopted this as the primary means of touch-up.

Any hard stone is ultimately grinding a new flat into the steel over the wear bevel. This works great if the angle is constant every time such as a Sharpmaker. Odd angle swipes can add up rapidly and necessitate a reset with a rougher stone, as most polishing grade stones can't readily recover anything but the slightest loss of angle/geometry. This is true of hard strops as well. With a rougher stone as a finisher you are likely removing more steel per recondition, but doing so less often - mostly a push.

When maintaining on a hard stone I normally make a few passes at the original angle with a rougher stone anyway, and then refresh the microbevel. The upside is I have to do a full reset less often, the downside is I need two abrasive surfaces. The end result is not much different from a hard strop.

That said, I do use both strategies. Commercial sharpening I only make a few passes on the hard strop coming off the microbevel stone. In my personal use even if I set out to maintain only on hard stones, much of the time I will eventually default to the hard strop as I find it to be a lot faster when I'm in a hurry and no real loss of cutting efficiency. I have a tough time sticking with any one stone type or strategy though. It all works, and you only acquire and keep skills by doing.
 
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