Why a leather strop?

[bigfred]

I have always used a leather strop to finish up the edge after sharpening a knife. My dad taught me that after first showing me how to use a sharpening stone. I have always wondered how and why the leather, a very soft material, will put such a good edge on steel. Anyone have an answer?

 

[Normark]

Hey Fred...

The strop actually polishes the edge enough to remove very small wire burrs...

Try jewelers rouge on it and it's even better..

ttyle Eric...

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Eric E. Noeldechen
On/Scene Tactical
http://www.mnsi.net/~nbtnoel
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Concealex Sheaths and Tool Holsters
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[Paracelsus]

The reason a soft material like leather helps to refine and maintain an edge is because All edges are really saws. They have small teeth. A 30X microscope or a jewlers loupe will help you to see these teeth.

The finer the final grit of your sharpening stone, the smaller the teeth along the edge. Because you sharpen on a stone by pushing the edge into the stone, the teeth along the edge get bent in different directions. Stropping on leather (I like to use 10,000 grit green chromium oxide polish on my strops) by pulling the knife Away from the edge on the leather will line-up the small irregularities in the edge. This will produce an edge ideal for push cuts. A very fine and polished edge may not be best for All knife applications.

Some folks like to use a steel for the same purpose. Stropping and steeling can maintain an edge in a optimal condition during use, delaying the need to resharpen on a stone.

This topic gets discussed a lot around here. You can use the search function at the top of the page to search the forums for past threads on strops and sharpening. I think you may enjoy these threads:

How to strop: http://www.bladeforums.com/ubb/Forum32/HTML/003186.html

Making a Strop: http://www.bladeforums.com/ubb/Forum32/HTML/002391.html


Welcome to BladeForums BigFred!


Paracelsus, hoping this helps in the never ending quest for Sharpness and Understanding

 

[Jeff Clark]

I like to finish most blades by honing with extra-fine ceramic rods then stroping with leather without any polishing compound. My (unproven) conception is that the ceramic leaves small and sharp micro-serrations on the edge. Plain leather stropping aligns, straightens and removes small imperfections, but does not polish away the micro-serrations. The final edge shaves well and cuts well.

 

[johno]

Lately I've been going to the strop after the soft Arkansas stone for most applications, with the intent of ending up with a bit of polish on a toothier edge. If the steel is hard enough and the sharpening technique good enough one can forgo the strop, the Dozier factory edge being a good example of an agressive, toothy edge that still cuts hair on one's arm. I'll guess that for most people the strop effectively 'hides' less than optimum technique using a stone, it certainly does for me, as it is difficult to consistently work an edge with increasingly smoother stones without increasing the sharpening angle. It's also difficult to get a lot of edges straight enough to be able to use on wider, smoother stones, where again the compliance of the strop helps to overcome the problem.

I find that with the typical gummier, softer stainless steels it's better to go to a finer stone before stropping, or to just finish off with a fine stone or ceramic stick. I'll guess it's because the wire edge is gummier with the softer stainless and doesn't respond as well to stropping, and is also why the Spyderco sharpeners are so popular.

 

Steel is a very tough stuff, BUT:
when your edge is only a few microns (micrometers, I mean) thick you may bend it with a feather....
So using "any" pressure with a hone will bend or breakout parts of the very edge.
Stropping will align these irregularities (a bit) giving you a "finer" edge, but not necesseraly a "better one" for cutting.
I do align with Spyderco's white stone used like a "steel" with "no pressure" at all.
In the "jig", so the angle stays constant.
Happy sharpening

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D.T. UTZINGER

[This message has been edited by ZUT&ZUT (edited 05-13-2000).]