Stroping

T

tsu15

Joined
Oct 21, 2012
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What would balsa strops or leather strops do? Are they for a mirror polish?
 
Generally, in my understanding, they remove the burr and/or refine the finished edge and make it smoother. It will polish the edge somewhat, but will not make it a mirror finish. If used with a compound containing some kind of abrasive, it will also tend to grind the apex somewhat. More knowledgeable people than me may give a much better explanation, or refute what I think. I am a nooobie at this and am only guessing based on some observations from my use of strops.

Omar
:rolleyes:
 
Getting a mirror polish on an edge depends on a full, tight sequence of abrasive grits used in sharpening. A strop won't do it alone, UNLESS the previous appropriate polishing steps are taken first. A mirror only happens when the scratch patterns become very, very fine, and most of that work needs to be done with the stones. Stropping provides the finishing touches only. Very fine polishing compounds, often down to 1 micron size or less, are usually used for this on the strop.

Aside from polishing, stropping is mostly used for aligning an edge (straightening a bent wire edge), and stripping away some very fine burrs.
 
Obsessed with Edges said:
Getting a mirror polish on an edge depends on a full, tight sequence of abrasive grits used in sharpening. A strop won't do it alone, UNLESS the previous appropriate polishing steps are taken first. A mirror only happens when the scratch patterns become very, very fine, and most of that work needs to be done with the stones. Stropping provides the finishing touches only. Very fine polishing compounds, often down to 1 micron size or less, are usually used for this on the strop.

Aside from polishing, stropping is mostly used for aligning an edge (straightening a bent wire edge), and stripping away some very fine burrs.
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Wut he said... That "UNLESS" part is the deal-breaker. Pay attention to it. A strop isn't magic. It's part of a series of steps used to create a very fine edge. Without the proper previous steps, a strop 'can be' next to useless. Keep in mind too, technique is as important as the strop being used.


Stitchawl
 
I use the GATCO rod guided kit. I sharpen down to the extra fine and ultimate finishing hones. The edges that are created after the ultimate finishing hones are very sharp. I test before during and after sharpening to ensure my results.

I then go to the leather strops loaded with compound. After the stones and before the strops I could live with the edges. After the strops the edges are more refined and quite a bit sharper.

I agree with the sentiment someone else posted here a while back. Some say that toothy edges cut better than refined or polished edges. A toothy edge will degrade to the point that it needs sharpening. A polished or refined edge will degrade from its ultimate sharpness down to the toothy edges sharpness before finally degrading to the point that it needs to be resharpened.

I personally have not seen a material that a toothy edge will cut better than a refined edge.
 
Hard H2O said:
A polished or refined edge will degrade from its ultimate sharpness down to the toothy edges sharpness before finally degrading to the point that it needs to be resharpened.
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Depend on the edge geometry and brittleness of steel. A highly refined smooth edge more likely to deform/roll than degrade/fracture to toothy state. A rolled edge may performs poorly in compare to a dull toothy saw edge.
 
While we are talking about strops... How do you know when you have enough compound loaded on the leather?
 
Monofletch said:
While we are talking about strops... How do you know when you have enough compound loaded on the leather?
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The leather should still look like 'leather', but showing some coloration from whichever compound is used. For example, with chrome oxide (green) compound, you'd still see the grain and/or fibrous texture of the leather, but it would be tinted green in color. That's all that's needed. Some like to put a lot more compound on, to the point of it taking a 'caked' appearance, but only the very top of the thick layer will be interacting with the blade anyway. The compound that actually has opportunity to embed into the leather is what's doing most of the real work. Anything above that, which doesn't have something in which to embed/hold onto, will more or less be pushed around on the strop (it collects on the blade as well), and it can't work very effectively that way. Doesn't really harm anything, but it's additionally messy and doesn't add anything to stropping performance. In the sense that it doesn't embed, it actually just gets in the way, and will even degrade performance. I originally applied heavy layers of compound to mine, when first making them, but soon figured out performance improved noticeably after I cleaned most of the excess off.
 
Thank you David. Another dumb strop question.... Smooth side or rough side of the leather? I use the rough side with great results WITHOUT compound. I have white and brown compound.
Also, if the compound is turning "black"- does that tell me it's working?
 
Monofletch said:
Thank you David. Another dumb strop question.... Smooth side or rough side of the leather? I use the rough side with great results WITHOUT compound. I have white and brown compound.
Also, if the compound is turning "black"- does that tell me it's working?
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Both sides will work well, but personally, I find the smooth side to be best, especially when used bare (without compound,) the stropping step AFTER using compound on a strop. This is why Barber strops are always smooth. Think of it as similar to diamond plates; interrupted pattern or continuous. The blade is only contacting the higher points on the rough surface, but as there are so many, it's still effective. It just takes a few more strokes to do the job.

As for turning black, yes, that's the metal that's being removed. No need to worry about it, as it will still be working even when completely black. Many people feel the need to remove it (using WD-40, lighter fluid, Coleman Fuel, or just scraping,) or you could just crayon on a bit more if you wish. Keep in mind that what is happening is going on at a microscopic level. What you are seeing with your naked eye is NOT what is happening at the microscopic point. That's still going on despite what you see. Eventually your entire strop will 'glaze' over, not just turn black. THAT is the point where you might get better results if you either clean or just re-charge the strop.

Stitchawl
 
Monofletch said:
Thank you David. Another dumb strop question.... Smooth side or rough side of the leather? I use the rough side with great results WITHOUT compound. I have white and brown compound.
Also, if the compound is turning "black"- does that tell me it's working?
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Stitchawl's input is good, regarding the 'black' stuff accumulating on the strops; it's no big deal, and does show the strop compound is working. I occasionally just wipe my strops with a dry paper towel, which removes a good bit of the loose steel swarf, and keeps the strop from 'glazing' for a long while, as stitchawl mentioned.

For me, I'll usually start out using the smooth side. BUT, the character of the rough side will vary all over the place, and sometimes I've used the back side of leather because it really does seem to work well, depending on the individual piece of leather. I have a leather belt, purchased from Cabela's, that has almost become my favorite strop, due to the character of the inside (rough) face of the leather. Works great as a 'hanging strop', with the belt looped around a bed rail, towel rod or whatever's handy. I applied a little bit of green compound to a 12" section of it as well (how many can say they actually wear their compounded strop? :D). I've also 'roughed up' the smooth side of veg-tanned leather to give it some velvety 'nap', which really holds compound well. I use some medium-grit sandpaper to do this, and vacuum up the debris/dust from the surface afterwards. I (strongly) don't recommend sanding a strop that's been specially prepared (cased) for razors, like horsehide, Russian, Illinois razor strops, for example; sanding those will ruin them. The 'plain' old veg-tanned leather, bought at craft stores or saddle shops, won't be diminished by it. I have occasionally sanded down a really dirty strop (after wiping with a WD-40-moistened paper towel), before re-applying compound. Again, I use a vacuum to pick up as much of the surface debris (including possible particles from the sandpaper), before re-applying the compound.
 
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bluntcut said:
Depend on the edge geometry and brittleness of steel. A highly refined smooth edge more likely to deform/roll than degrade/fracture to toothy state. A rolled edge may performs poorly in compare to a dull toothy saw edge.
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Maybe. That is why I am careful to use cutting boards. I also ensure that there is nothing that might damage the edge behind what I am cutting.

The only rolling or chipping I have experienced is in the kitchen on blades that I have taken down to a very fine angle. Even then they still perform better than a non stropped and polished edge.

You need to set the angle to the task to avoid that kind of problem.
 
Hard H2O said:
I agree with the sentiment someone else posted here a while back. Some say that toothy edges cut better than refined or polished edges. A toothy edge will degrade to the point that it needs sharpening. A polished or refined edge will degrade from its ultimate sharpness down to the toothy edges sharpness before finally degrading to the point that it needs to be resharpened.

I personally have not seen a material that a toothy edge will cut better than a refined edge.
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bluntcut said:
Depend on the edge geometry and brittleness of steel. A highly refined smooth edge more likely to deform/roll than degrade/fracture to toothy state. A rolled edge may performs poorly in compare to a dull toothy saw edge.
Click to expand...

I have never observed a refined edge degrade to a toothy edge - the very act of refining the apex makes this all but impossible without some form of micro-chipping. Use-dulled edges, whether toothy or refined, tend to fail as the apex becomes more radiused from friction or pressure. In my experience,when used in a friction application a toothy edge will far outlast a polished edge, and a polished edge will far outperform a toothy one in a pressure application. There is a sweet spot where one can balance characteristics (toothy/polished), but an edge specialized for a given task will (all other things being equal) always outlast one that hasn't been so customized, simply polishing an edge to a high level of uniformity is no guarantee of performance across a wide spectrum of tasks.


That said, I recall Hardheart posting a wealth of info from some CATRA testing he participated in that seemed to indicate (at least re the CATRA testing media) that inclusive angle was the biggest factor in longevity over edge prep - toothy or polished. Also, lest I stray too far from the topic, I always finish with some form of stropping, even if its on plain newspaper or paperboard. And while I cannot speak for balsa, I strop quite a bit on hardwood and get good results with everything from black emery in the 15-20 micron range right up to Flexcut Gold in the .5-1 micron range. If I want an even more polished edge I'll apply the same compounds to newspaper.
 
I am sorry if I didn't make my meaning clear. I didn't mean to say a polished edge would become toothy. I meant that a polished edge is sharper from the start and would degrade to become as sharp as a toothy edge before the sharpness would finally degrade to require work.

It is the sharpness I am comparing not the physical characteristics of a refined edge versus a toothy edge.
 
Hard H2O said:
I am sorry if I didn't make my meaning clear. I didn't mean to say a polished edge would become toothy. I meant that a polished edge is sharper from the start and would degrade to become as sharp as a toothy edge before the sharpness would finally degrade to require work.

It is the sharpness I am comparing not the physical characteristics of a refined edge versus a toothy edge.
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Understood, I have to respectfully disagree on the the overall statement anyway. A polished edge that has become dull frequently cannot execute a draw cut of any note, leaving the user to apply ever increasing amounts of pressure. A sharp toothy edge might require a similar amount of pressure to execute a pressing cut, but leaves the user with the option of executing a drawing cut with far less pressure. When working with some materials this can make a huge difference in functional longevity (all other things being equal - inclusive angle, steel type etc). All depends on what one is cutting. For use primarily in a food prep environment I have to agree with your statement, for general use I do not.
 
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