Are Leather Strops pointless? Yes! Yes they are.

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I made this recently with the goal of assessing a leather strop vs a denim strop embedded with Chromium Oxide (CrOx). After generally finding a sharper edge off of my CrOx embedded suede strop vs the leather of the same strop, I thought I'd DIY this little hands held strop and see if it was the same outcome.

It was.

This is beginning to make me question leather strops all together.

Maybe my technique sucks, or there's something I'm missing, but if anything, I find I get a duller edge off of leather. Especially if I go CrOx, wipe the edge and then go to leather.

I'm the same person sharpening three different knives using the same technique on all knives and surfaces. Am I the problem?

After reading up on "The Science of Sharp," (https://scienceofsharp.wordpress.com/2014/08/13/what-does-stropping-do/']https://scienceofsharp.wordpress.com/2014/08/13/what-does-stropping-do/']https://scienceofsharp.wordpress.com/2014/08/13/what-does-stropping-do/ )
I find even less of a pro argument for leather. Yes it polishes, but so does other material that doesn't cost an arm and a leg.

Thinking high level, there are likely only a few things that could be happening on a micro level to the steel to polish or sharpen:
Alignment - pushing the steel back into a single apex.
Abrasion - removing steel
Melting - Causing steel to melt and smooth/flatten
Polishing - Adding something to fill the holes

So far, it seems leather does none of the above, except maybe slight melting and abrasion. I have no idea what leather's grit would be, but I imagine it would be so high, it would do practically nothing. Otherwise, one would have to strop so much on leather to "sharpen" at it's really high grit that the risk of melting and bending the edge would be very high.

In other words the risk greatly outweighs the rearward.

Is there a benefit to leather when there are so many other options that seem better AND cheaper?

Does leather have a grit?

Should leather be kept for sheath and sweet period clothing?

What do you think experienced blade forum community?
 
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My own preferred 'best use' for leather stropping, either with compound or bare, is aimed mainly at removing fine remnants of burrs still clinging loosely to the edge. In some circumstances and with some steel types, I've found it works more consistently for this than other means I've tried. In particular, I've liked it with 1095, CV and simpler stainless, like 420HC, for just a few finishing swipes after I've done most of the refinement on a stone. Sometimes I've used it with a relatively light application of green compound; but, most of the time, I've been happy with just using bare leather alone, or leather with a long-neglected 'hint' of previously-applied green compound, having not been refreshed for a long time. A tiny bit of the compound left over can be useful for the light burr cleanup; but I've found a heavier application of it to be unnecessary, and sometimes even counterproductive.

I wouldn't rely on leather much, either with compound or without, if I were still looking to do additional shaping or polishing of the edge. Without compound, it won't do much for that anyway. And with compound, it's more likely to round off and/or dull the apex, if the touch isn't very, very light and if one doesn't go too far with it (too many passes). If the compound has any aggression at all, in metal removal, the inherent compressibility of leather underneath it is only going to make the compound work faster to round off the apex.

For aggressive polishing and some thinning of the edge, I've liked hard-backed denim better, if relying on a strop to do this in the first place. If the denim is very firmly backed, and especially if it's fairly thin (old jeans are good), denim holds compound extremely well, and helps it work very, very aggressively for fast polishing while still doing a pretty good or excellent job in keeping the apex crisp and thin.


David
 
you can make a strop out of nearly anything. compound on paper on top of glass is very cheap.

as for a strop in general, you need a strop of some kind to remove the bur. if you sharpen without getting a bur, then you wont need a strop.

ive had zero issues (if used correctly) with a leather strop with compound.
 
Been using a straight razor for nearly 50yrs. On that, plain smooth leather is a must. on a knife; maybe. It will remove a burr and for a push cut very useful. On a slicer with a more toothy edge; not a real issue IMO. Greg
 
Leather is traditionally used because it will grab a burr and pull it off of steel.
Other than resiliency and texture, there is no reason to use any compounds on leather.
 
I think my stroppig technique is bad also. Or I take too many passes. No matter how light of a touch or what angle I choose I always seem to dull the edge. I have gone to using a felt block or piece of cork for deburring and they work well for me.
 
This is beginning to make me question leather strops all together.
Maybe my technique sucks, or there's something I'm missing, but if anything, I find I get a duller edge off of leather. Especially if I go CrOx, wipe the edge and then go to leather.
I'm the same person sharpening three different knives using the same technique on all knives and surfaces. Am I the problem?
Hi,
How sharp are you before the leather?
How do you deburr?

If you're burr free (double angle deburr) and can push cut newspaper/phonebook paper,
and stropping on leather is making the edge cut worse,
sounds like your angle is too high for the squishyness of the leather,
or you're using too much force for the squishyness of the leather .
Use permanent marker trick to find the correct stropping angle.
Strop using lighter force.
Strop using fewer passes.



I've been stropping for a few months now, I too was disappointed it wasn't like magic :D

So far, it seems leather does none of the above, except maybe slight melting and abrasion. I have no idea what leather's grit would be, but I imagine it would be so high, it would do practically nothing. Otherwise, one would have to strop so much on leather to "sharpen" at it's really high grit that the risk of melting and bending the edge would be very high.
In other words the risk greatly outweighs the rearward.
Does leather have a grit?
Yup, leather is essentially not abrasive, the largest effect is bending/fatigue , and thats not always a good thing :)

It does contains sodium silicate in sizes of 2 to 100 nm in diameter or 0.002-0.1 micron or ????-160,000 grit (thread has interesting info/links)
but it is in very low quantities/density so cutting isn't the primary effect.


Is there a benefit to leather when there are so many other options that seem better AND cheaper?
Should leather be kept for sheath and sweet period clothing?
Its mostly about the squish :) and the grain

Do you live in an urban area?
I recently discovered the "free stuff" section on craigslist.org
every week (or day) somebody is giving away a leather chair/couch/lovseat/sleeper/sofa...
half the time they leave them out on the curb or by the garbage dumpsters,
and thats just the people who bother to post to craigslist,
people in dorms/apartments/condos toss stuff all the time,
...
A few months back I passed 5 leather chair/sofa on my way to mailbox
I didn't cut off the leather because I foolishly though somebody would take them
or at least take the leather,
but nobody did, in the garbage it went,
most of these giveaway leather furniture ends up in the garbage dump
and yards of it are free for the cost of 10min walk or a 10min ride :)

A pickup truck, a curbside leather couch, a couple of choppers ... lots of fun potential :D
 
I think my stroppig technique is bad also. Or I take too many passes. No matter how light of a touch or what angle I choose I always seem to dull the edge. I have gone to using a felt block or piece of cork for deburring and they work well for me.
Hi,
Sounds very much like you still have burr
Have you ever tried double angle deburring before stropping?
Thats 1-2 ultra light (under 100 or 50 grams on a scale) edge leading alternating passes at double the angle?
Shearing off a Burr Using High Angle Passes - Steel_Drake
A Comparison of Deburring Techniques - Steel_Drake
19m26sec A Brief Introduction to Coarse Particulate Abrasive Stropping - Steel_Drake
30micron pasted strop From Dull to Crossgrain Pushcuts in 5 Minutes - Steel_Drake
 
So leather is somewhat pointless, with some specific exceptions.

Glad I'm not crazy.

If burr removal is the purpose, there are so many ways to achieve that, leather seems like a waste. Paper, newsprint, old jeans, 1x per side on the hone, other hone techniques, there's so many other options. Leather probably makes better sheath material.

I'm all for recycling, I just don't really trust discarded furniture. Bed bugs scare me. And I'm not confident enough to do the leading edge burr removal. You two are brave.

How straight razor are any different, I don't really understand. Yes there are different angles, steels and tempering involved, but we're still talking about steel and an edge.

I haven't done a tonne of tests with my Dovo straight razor yet, but did find a vast improvement when I started finishing using CrOx after trying 10,000 Chinese stone to leather. Something about the CrOx seems to beat leather, for me at least.

I'm interested in Cubic Boron Nitrate paste (CBN) . Seems to be a natural step up from Chromium Oxide.
 
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I haven't used the Boron paste yet. But will. I use SiC grit/ slurry on a hard compressed leather, glued to a 2"X 4". The grit is around 250-300. Hard backed stropping. I strop light and not a lot of stokes for burr removal. Not refinement. This works well and keeps the edge rather coarse.
Around 400- 450. This also works for a stand alone tune up stropping of the edge. No stone work. So, little to no metal removal. Thus, saving the edge and giving it longer life. Some good benefits. DM
 
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How straight razor are any different, I don't really understand. Yes there are different angles, steels and tempering involved, but we're still talking about steel and an edge.
Razor steels are the same as knife steels, "heat treat" is done the same, edge angles are often somewhat lower than knives (not always the case). I'm not a straight razor user, but my understanding is that unless you own a very very fine stone (8k, 12k, or even finer), and can master that stone, you will want to be using plain leather to strop that razor for a comfortable shave.

With that said, I never have cared for stropping. I bought a leather strop a few years back with black compound on one side and green on the other. It sits unused! I like to do my complete sharpening process on the stones, stopping at what grit I think is best for the application that particular knife will likely see.
 
The leather on a strop you made looks awfully sick. This is going to promote rounding of the edge
 
The leather on a strop you made looks awfully [thick]. This is going to promote rounding of the edge

Yup! You're definitely correct. Live and learn.

I remember reading somewhere that straight razors are about 7 degree edge angle. Plus they're hollow ground, so super slicey.

After using my straight razor for 6 months, stropping before and after every use, the edge died. It was completely unusable.

I tried using my 10k Chinese stone then leather to bring it back, it was horrible. It could barely cut arm hairs. I now realize that a harder high grit stone would be better, the Chinese one is very soft. Also, going to a smooth section of suede embedded with CrOx rendered the best edge I've achieved so far. Based on what I've read, Cubic Boron Nitrate takes the edge/polish to the next level.

Check this out. This guy shows an 800x magnification of CrOx vs CBN. Skip to 8:50.
 
Is there a benefit to leather when there are so many other options that seem better AND cheaper?

Does leather have a grit?

Should leather be kept for sheath and sweet period clothing?

What do you think experienced blade forum community?

Plain leather can have a beneficial effect, this effect is going to be most pronounced as the edge angle and stock thickness become more acute and thin - like on a straight razor. In that case it is mostly straightening out the edge and removing any metal fines and residual compound. It will also be having a mild burnishing and polishing effect.

Even veg tanned leather often uses silicate in the process of tanning, and stropping leather is often (exclusively) made from grazing animals' hide - the plants uptake silica salts and oxides and when eaten, the digestive system of the critter passes particles as large as 100 micron or more, certainly particles in the 20 micron range and smaller are absorbed and make it well into the blood stream. I honestly don't know how far into the skin they go, but either by migration or in the tanning process there are oxides of silica in the leather.

How hard the leather is makes a big difference in the effect it will have. You can do a quick experiment with a sheet of paper wrapped around a brick, and one wrapped around a piece of wood. Stropping on a significantly harder surface will seriously effect the burnishing rate/effect. I have kept an Aus8 blade arm hair shaving sharp for weeks of daily use by only stropping on plain paper over a hard surface. In fact it required less and less strop to work time as I went, right up until it dulled the final time and couldn't be restored without added abrasives.

Once you start applying compound to anything, the mild effects from plain leather will be left far behind in terms of polishing. It won't work well for maintenance either except on those extremely thin shaving razors, tho some folk strop on plain leather and swear by it. Again, how hard the leather is makes a big difference - it should be about as hard as a seasoned soft wood.

Personally I use paper over a hard surface or Washboard most of the time - I do have one or two around my bench though. If I need the compound to have more bite I use thinner paper or apply a little more force. The failure mode on this type of really hard strop is breakup up the final few microns of the edge, easily recovered with a few more passes at lighter pressure or avoided in the first place by keeping pressures below a pound or so.

If I need a smoother finish I use more sheets/thicker paper and less pressure. Now the failure mode is rounding, so this needs to be done softly. This is the same role as most leather strops loaded with compound - light use and light pressure so it doesn't load up fast or round the edge.

So whether it has a role for you is going to depend on how its used, what you expect it to do, the properties of the specific piece of leather and a couple of other variables that I can't think of at the moment. I seldom use it myself anymore.
 
i use horse butt leather.

if you google "horse butt leather", no quotes. 2nd link is what i have.

leather regardless is NOT pointless.
 
So leather is somewhat pointless, with some specific exceptions.

Glad I'm not crazy.

If burr removal is the purpose, there are so many ways to achieve that, leather seems like a waste. Paper, newsprint, old jeans, 1x per side on the hone, other hone techniques, there's so many other options. Leather probably makes better sheath material.

I'm all for recycling, I just don't really trust discarded furniture. Bed bugs scare me. And I'm not confident enough to do the leading edge burr removal. You two are brave.

How straight razor are any different, I don't really understand. Yes there are different angles, steels and tempering involved, but we're still talking about steel and an edge.

I haven't done a tonne of tests with my Dovo straight razor yet, but did find a vast improvement when I started finishing using CrOx after trying 10,000 Chinese stone to leather. Something about the CrOx seems to beat leather, for me at least.

I'm interested in Cubic Boron Nitrate paste (CBN) . Seems to be a natural step up from Chromium Oxide.
Hi,
Get a practice knife (kitchen paring), conquer your fears :)

Also there is an online "Bed Bug Registry" to inform your covered furniture hunting,
however harvesting leather from curbside furniture should pose minimal risk,
double bag it, go directly to laundromat and wash it :)
 
I use thin, hard leather with chromium oxide compound, or diamond spray on balsa.

I bought some veg-tanned leather at a local Tandy, hand cased it to make it firmer, and applied the compound. Works really well for me for finishing up after sharpening. I can get arm shaving results relatively quickly on simple steels like 1095 or 420HC/440A by going straight from a 400-grit India stone to the strop. I use the diamond/balsa strop for kitchen knives and steels with hard vanadium carbides in them, after a progression on diamond hones or water stones.

You may not get good results out of a leather strop, but mine work great.
 
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