The importance of stropping edge tools

[Derek Cohen (Perth Oz)]

In a woodworking context, and in my view, all it does is remove rag -- the last shards of the burr -- and that's it. It if smooths or contours the edge in any way that's not stropping, that's back to honing.

OK; we now have a definition of what stropping does; it removes the last traces of the burr, but (again defining what stropping isn't) not by abrasion.

So what is the mechanism of stropping, and (for bonus points) why is this action different in linen versus leather?

I'm aware that I am (in effect) asking "what is stropping" again and again, but since I keep failing to get a concrete answer, I'll just keep asking.

BugBear

Hi BB

I thought this was obvious? Or perhaps this is just my understanding ...

Stropping involves the bending of the wire, which occurs from one side of the bevel to the other, until it snaps and falls off.

I imagine that, as a blade dulls, the edge is not just worn away, but also bent back, especially in softer steels (overly hard steels are more likely to fracture). Stropping a used blade either straightens the "wire" created from use, or it straightens the edge (moving the steel). I have microscopic photos of the bending from use, but not seen photos taken after stropping. This is all just my supposition. Someone should taken some photos of the process. Or do you know of any?

The point that I was making in my previous post - which are so important that the forum software duplicated it! - was that the edge of the blade always has some vestige of "wire", and that the smaller it is, the less its incursion. Hence, a compound "strop" on hardwood is better than a plain leather strop.

Regards from Perth

Derek

 

[bugbear]

I'm aware that I am (in effect) asking "what is stropping" again and again, but since I keep failing to get a concrete answer, I'll just keep asking.

Hi BB

I thought this was obvious?

Not to me.

Or perhaps this is just my understanding ...

Stropping involves the bending of the wire, which occurs from one side of the bevel to the other, until it snaps and falls off.

OK. This is testable; try simply pressing the tool (on alternate sides) on sheet glass; this should flex the edge repeatedly, and ultimately fatigue away the wire.

I imagine that, as a blade dulls, the edge is not just worn away, but also bent back, especially in softer steels (overly hard steels are more likely to fracture). Stropping a used blade either straightens the "wire" created from use, or it straightens the edge (moving the steel). I have microscopic photos of the bending from use,

I've not seen those - are they on the web somewhere?

but not seen photos taken after stropping. This is all just my supposition. Someone should taken some photos of the process. Or do you know of any?

No - the intersection set of people interested in the minutiae of sharpening and people with access
to electron microscopes seems to be very small.

The point that I was making in my previous post - which are so important that the forum software duplicated it! - was that the edge of the blade always has some vestige of "wire", and that the smaller it is, the less its incursion. Hence, a compound "strop" on hardwood is better than a plain leather strop.

Thanks for a helpful reply.

BugBear

 

[essexalan]

According to Chris Pye strop is an older form of strap meaning "a strip of leather", he does mention loading the strop with a fine abrasive although I do not know if this was standard practice among barbers of old. So I would say that stropping means the action of improving or enhancing the edge of a cutting tool by the use of light edge trailing strokes on a suitable surface. A suitable surface has come to mean a plethora of substrates loaded or otherwise including stones themselves. If I feel a burr remaining when I take to the strop then I take the steel back to my last stone although a loaded strop will abrade this away. There is a natural law that states that the action of rubbing two surfaces together abrades both surfaces, even polishing is abrading metal. Leather is definitely abrasive and you can form a microburr with over enthusiastic stropping. Perhaps linen has a less abrasive action than leather your face will tell you when you run a razor over it. My Dad used a well oiled strop and I can never remember him using stones on razors, chisel and plane blades were finished on the palm.

 

[bridger]

This guy covers it:
https://scienceofsharp.wordpress.com/20 ... opping-do/

 

[bugbear]

This guy covers it:
https://scienceofsharp.wordpress.com/20 ... opping-do/

I probably won't be posting in this thread for a while.

I've got some blog to read.

Thank you!

BugBear

 

[Trafalgar]

Per the blog link posted above: 100+ laps on any material is no longer stropping as I understand it, at least not in a woodworking context.

 

[G S Haydon]

I'm aware that I am (in effect) asking "what is stropping" again and again,

BugBear

A practical and experienced woodworker's response to that question will be to tell you how the process improves the quality of their work. That is what stropping is to a practicing woodworker. Their mind is applied to their work, each version of what each person calls stropping will be different. That's shown in the responses, to a practicing woodworker as myself the information provided by people so far, is more than enough to understand how stropping works and how it can be applied to the work at hand.

Your question is a little different, as your perspective seems more aligned to personally discover a definition beyond that. Bon voyage on your reading. Perhaps also making something and sharpening in a few different ways as described by people might give some illustration. With practical things like woodworking sometimes you'll need to put down the book and experience it.

Good feedback from the OP, good to see the work is improving thanks to the add of a stop.

 

[Paddy Roxburgh]

In a woodworking context, and in my view, all it does is remove rag -- the last shards of the burr -- and that's it. It if smooths or contours the edge in any way that's not stropping, that's back to honing.

OK; we now have a definition of what stropping does; it removes the last traces of the burr, but (again defining what stropping isn't) not by abrasion.

So what is the mechanism of stropping, and (for bonus points) why is this action different in linen versus leather?

I'm aware that I am (in effect) asking "what is stropping" again and again, but since I keep failing to get a concrete answer, I'll just keep asking.

BugBear

STOP ASKING THE SAME BL@@DY QUESTION OVER AND OVER AND OVER, I'VE HAD ENOUGH OF IT, i CAN'T TAKE ANY MORE. WHY CAN'T YOU JUST BE HAPPY WITH THE ANSWERS YOU'VE GOT? ARGGGHHHHH, YOUR DOING MY HEAD IN.

See above for example of stropping (hammer)
Paddy

 

[D_W]

This guy covers it:
https://scienceofsharp.wordpress.com/20 ... opping-do/

I was a bit stunned at first that in that progression, there was a huge foil ripped off by the linen. That shouldn't be so, but if it's in the article, I missed the comment about it (it's certainly possible to use a belgian stone to raise a fat wire edge if you use too much pressure). In the comments below, the blog owner admitted that the razor isn't properly sharpened.

Linen doesn't have anything to do with woodworking, but in razoring, it certainly increases the subjective sharpness of an edge, and aligns it faster than leather would.

There is no good linen made currently that I'm aware of. Nobody seems to know what the treatment was that was added to old linen. Some of the "linens" marketed now, even if they are genuine untreated linen, are stiff and harsh and they degrade an edge.

 

[bugbear]

This guy covers it:
https://scienceofsharp.wordpress.com/20 ... opping-do/

I was a bit stunned at first that in that progression, there was a huge foil ripped off by the linen. That shouldn't be so, but if it's in the article, I missed the comment about it (it's certainly possible to use a belgian stone to raise a fat wire edge if you use too much pressure). In the comments below, the blog owner admitted that the razor isn't properly sharpened.

Linen doesn't have anything to do with woodworking, but in razoring, it certainly increases the subjective sharpness of an edge, and aligns it faster than leather would.

There is no good linen made currently that I'm aware of. Nobody seems to know what the treatment was that was added to old linen. Some of the "linens" marketed now, even if they are genuine untreated linen, are stiff and harsh and they degrade an edge.

That all sounds a bit more zen than concrete to me.

BugBear

 

[D_W]

This guy covers it:
https://scienceofsharp.wordpress.com/20 ... opping-do/

I was a bit stunned at first that in that progression, there was a huge foil ripped off by the linen. That shouldn't be so, but if it's in the article, I missed the comment about it (it's certainly possible to use a belgian stone to raise a fat wire edge if you use too much pressure). In the comments below, the blog owner admitted that the razor isn't properly sharpened.

Linen doesn't have anything to do with woodworking, but in razoring, it certainly increases the subjective sharpness of an edge, and aligns it faster than leather would.

There is no good linen made currently that I'm aware of. Nobody seems to know what the treatment was that was added to old linen. Some of the "linens" marketed now, even if they are genuine untreated linen, are stiff and harsh and they degrade an edge.

That all sounds a bit more zen than concrete to me.

BugBear

What part of it?

 

[Cheshirechappie]

This guy covers it:
https://scienceofsharp.wordpress.com/20 ... opping-do/

That suggests to me that stropping is more a burnishing process (plastic deformation - moving metal around) rather than an abrasive process (removing metal). Putting it another way, the main effect seems to be slightly reshaping an edge by deforming metal to where it's wanted to make a better cutting edge, rather than by abrading it to form a new edge in new metal.

From a purely personal observational point of view, that rather confirms what I find when using a slate polishing stone. There seems to be only slight metal removal, but when I treat tool edges by only trailing them on the stone (rather than the usual honing practice of back-and-forth), I end up with edges that seem sharper than almost any other way I've tried. I've noted the same effect on an ultra-fine ceramic stone too. That practice seems to both remove the wire edge from the main honing stone (fine India in my case, or medium ceramic in the past), and burnish the honed edge to a better 'finish' than the honing stone leaves.

That effect does not happen if I use the same back-and-forth technique on the slate as I use on the India, or at least, not as quickly.

I've no proof of this whatever, but my suspicion is that leather, palm of hand, piece of hardwood dressed with compound or undressed, or polishing stones, all do the same thing - burnish rather than abrade.

 

[memzey]

I always thought that the purpose of stropping was to bend the last jagged vestiges of the wire edge back and forth until it breaks off cleanly. Not so much abrading metal away as weakening it through repeated deformation.

 

[ED65]

As wonderful as the information is on scienceofsharp I think we need to be realistic about what the take-home message here is as far as how we would typically strop. When I strop I get a noticeable improvement in shine, and polishing is generally understood to be largely an abrasive process (material removal).

Now despite what the above shows about plastic deformation is there much of that happening stropping the way we do? Well that's going to depend.

I don't know about anyone else here but I'm not stropping 100 strokes every time! And I'm not using a very firm unloaded strop. Don't have time for that kind of lark. I'm doing less than 30 strokes on a loaded softish strop. So as far as my experience of stropping goes I'm confident it is nearly entirely an abrasive process, what about you?

 

[Cheshirechappie]

As wonderful as the information is on scienceofsharp I think we need to be realistic about what the take-home message here is as far as how we would typically strop. When I strop I get a noticeable improvement in shine, and polishing is generally understood to be largely an abrasive process (material removal).

Now despite what the above shows about plastic deformation is there much of that happening stropping the way we do? Well that's going to depend.

I don't know about anyone else here but I'm not stropping 100 strokes every time! And I'm not using a very firm unloaded strop. Don't have time for that kind of lark. I'm doing less than 30 strokes on a loaded softish strop. So as far as my experience of stropping goes I'm confident it is nearly entirely an abrasive process, what about you?

I'm just interpreting the evidence presented in the scienceofsharp link. It's the best evidence I've ever seen on what's happening during stropping. That doesn't make it final and conclusive, of course. However, one pass over a stropping medium (or perhaps some stropping media) could cause some deformation of metal at a cutting edge; many passes could burnish an edge quite extensively. It does seem to fit with practical experience. Well, mine anyway.

If you know of any evidence that shows stropping is an abrasive process, lob it into the mix and let's assess it.

 

[Trafalgar]

What is "burnishing?" :wink:

 

[essexalan]

What is "burnishing?" :wink:

It's like polishing or sharpening without removing any metal
:wink: The strop actually has magical properties whereby it replaces metal, fills in any scratches and makes the edge sharper.

 

[Cheshirechappie]

What is "burnishing?" :wink:

Plastic deformation - moving metal around. Like using a burnisher to turn a hook on a card scraper.

 

[Trafalgar]

Yes of course but it's hard to imagine linen providing a similar phenomenon but I suppose the photos don't lie.

 

[essexalan]

Probably would not work with burnishing cream or a burnishing cloth either. Oddly the same result can be obtained using a sharpening steel on softer steel knives. Never worked with razors so no idea you would even attempt that with linen let alone succeed but then anything harder would damage the razor I suppose. Any plane irons or chisels that deform to that extent I would consider unfit for use. Of course all this will be fixed when PM-V21 is released, self sharpening of course.