STROPPING A BLADE ON A LEATHER BELT?

Cosmic Superchunk

Cosmic Superchunk

Joined
Jan 28, 2001
Messages
3,709
I recently talked to a guy that says he gives his knives a touch up be stropping the blades on an old leather belt. He says he just oils the blade and stropps the blade away from the cutting edge. I've seen barbers do this, but does this technique really work? HAs anyone else ever tried this?
 
It works by aligning the edge (dullness can be caused by the edge rolling over) and/or polishing the edge. I strop against my denim jeans without any oils or pastes. It is a good way to finish up a blade after normal sharpening or to touch up an already sharp edge.

Chris
 
Yes, it will. Another common method is to strop the blade against the cardboard backing of a common paper pad (like a legal pad). The addition of metal polishing compound is advocated (clever play on words unintended) by some.

Another way to do it is to buy a special strop and Al0H3 (alumunum hydroxide) powder to use for stropping. I have done this.

The thing which actually works best for me is a small ribbed steel. Walt
 
A stropping will draw steel out towards the edge and is a great technique for getting a fine edge on softer steels that tend to develop a distinct wire edge when honing. Harder steels like ATS-34 and BG-42 can be sharpened well just using stones, and CPM S90V is so wear resistant that all stropping will do is polish the edge up nicely.

I prefer a piece of leather glued to a flat board instead of a belt when stropping to it keep a flat edge. With a belt or strap you get a convex edge, which some prefer, of course.


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James Segura
San Francisco, CA

[This message has been edited by stjames (edited 02-12-2001).]
 
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 jewelers 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

Try searching the word strop in this forum and any of the three blade discussion forum archives. This topic comes up a lot. I just copied the post above from a thread in archive#3 from last year.

Paracelsus
 
I've read that silica in leather acts as a fine abrasive.

In addition to polishing the micro teeth on a blade edge, stropping can also strengthen an edge by adding a miniature convex edge at the blade edge.

For folks who like narrow-angle blade edges, but would like to strengthen the thin edge, this addition of a miniature convex taper at the edge can result in an edge that is more resistant to rolling or chipping of the fine edge.
 
Well, terminology can get confusing here. A lot of people will talk about how a knife edge has "teeth". They might say that the edge looks like a "saw", or has "micro serrations". However, when you actually look at an edge under magnification, you might be surprised to discover that you can't see any teeth!

A knife edge doesn't really have "teeth", if what is meant by that term is denticulations that project out from the very edge, where the two bevels meet. There are some extremely small chips in the edge, which I guess you could call teeth, but those aren't visible at 30X magnification. In fact, it's hard to see them at 3000X magnification! Check out Juranitch's Popular Science article: here. Scroll down to the bottom for electron mircroscope pics of an edge.

An edge might not have "teeth", but it does have "furrows".
smile.gif
Furrows are the little grooves on the face of the edge bevel that are created by an abrasive hone. The less abrasive the hone is, the less pronounced the furrows are. It's hard to see the furrows with your naked eye, but they're easily visible with a loupe or magnifying glass.

Furrows increase the width of the actual edge and create drag as you cut. Stropping helps burnish the edge bevels by removing these furrows. A strop is an abravise, just like any stone, but it's very, very fine. So, you could certainly also use it to remove a burr or add some convexity to an edge.

I used to use an old leather belt, sans polishing compound, for stropping. It worked pretty well, but I decided stropping wasn't for me; it was an unnecessary step in the sharpening procedure for my needs. A rougher edge seems to last longer and doesn't tend to slide through fiberous material - qualities you look for in an edge made for "using".

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Cerulean

"My good reason to carry a knife is that God gave me rather weak teeth and rudimentary claws in an evolutionary trade-off." - J.K.M.

[This message has been edited by cerulean (edited 02-13-2001).]
 
Cerulean, thanks for the link, that's a great article.

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Jason aka medusaoblongata
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"To give is a need, to receive is mercy." - Thus Spoke Zarathustra
 
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