Does stropping actualy do anything?

I just read Professor Verhoeven's paper on sharpening. It is very detailed and contains electron micrographs of many blade edges before and after variuos sharpening procedures. At several points he tests plain natural leather strops and finds the following:

It was the opinion of the author at the start of these experiments that clean leather strops would contain sufficient levels of natural abrasives adequate to produce significant improvements in the edge quality. Therefore experiments were done initially on clean leather strops.

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Figure 24 presents micrographs of the blade of Fig. 23 after it was stopped on the Butz strop in the clean condition. The stropping procedure used the same 10 4-stroke cycles. The stropping action on the clean leather does not appear to have had much effect on the condition of the as-ground edge. The bur shown in the edge views may be just a bit smaller, but it is only a minor effect. The abrasive grooves along the faces appear to be little affected by the action of the stropping. This result is typical of what was found on additional experiments using the second clean leather strop described above.

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The effect of loading the leather strop with the chrome oxide compound prior to stropping is shown by comparing Figs. 24 and 26. The chrome oxide abrasive used on the blade of Fig. 26 has produced a dramatic reduction in the size of the remnant abrasive grooves on the face of the blade. As shown in the edge view of Fig. 26 the bur width is on the order of 0.4 to 0.5 microns. Comparing edge width and edge straightness to that of the razor blade standards of Figs 7 and 8, one sees that the quality of the Fig 26 edge is close to these standards.

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As a result, several initial experiments were done with clean leather strops, including an experiment with alternate 3 cycles of 4 leather stropping plus a single 6000 grit sharpening. In all cases the clean leather stropping proved ineffective in comparison with the dramatic improvement found with the chrome oxide loaded strop illustrated in Fig. 26.

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3 Stropping of the waterstone sharpened blades on clean leather strops had little effect upon the geometry of the as-sharpened blades. The abrasive grooves on faces and the bur size along the edge were not significantly modified. The burs on 600 grit pre-sharpened blades were not effectively removed. Apparently, the natural abrasives in clean leather, on either the hard or soft side of the leather, is not adequate to produce a significant abrasion of the surface.

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The stropping experiment on clean leather employed a flat leather strop attached to a board. The experiment was similar to that of section [4], p. 19, except that it was done by A. Pendray in his shop, rather than by the author in his lab. As in section [4] study, it was found that the stropping operation on clean leather had little effect on the surface smoothness or bur geometry.

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2 The experiment with stropping clean leather confirms the previous experiments. The natural abrasives present on clean leather are not adequate to remove edge burs or surface abrasion grooves on stropping.

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5 Two independent sets of experiments utilizing stropping on clean leather showed similar results. Such stropping action is not effective in removing the as-ground burs or surface abrasion marks. Apparently, the natural abrasives in clean leather, on either the hard or soft side of the leather surface, are not adequate to produce effective polishing.

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Regarding the steel:

The bulk of the experiments were carried out on AEB-L stainless steel blades having a hardness of HRC = 60. A small number of comparative experiments were done on three non stainless steels, 1086, 52100 and a genuine damascus steel, at hardnesses of both HRC = 60 and 40.

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1 The edge roughness of steel blades sharpened with 1000 grit wheels on the Tru Hone machine and with 200 grit wheels on the Tormek machine show the same dependency on steel hardness. In both cases the edge roughness is significantly larger for blades at a hardness of HRC = 40 than for blades of HRC = 60.

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All of this seems to say that stropping on a clean leather strop has no effect on modern hard steels. Much softer steels seem to form much rougher edges with correspondingly larger burs. A plain leather strop MAY have an effect on that edge. This seems to imply to me that 200 years ago when razors were made form much, much softer steels that stropping may have had some small effect but now with modern steels it has very little to no effect at all. We have just carried over the tradition. It is also possible that straight razors have significantly different edge geometries that react differently to the strop. This is unlikely as the author compared all edges to a commercial Gillette razor blade and found that he was able to produce a nearly identical edge.

I would be curious to do an experiment. I could buy two identical razors, send both to the same honemeister then shave with each for 15 days, stropping one but not the other. I could then send both blades to an expert member here, somebody with years of straight razor experience and a sensitive face. They would not know which was which blade. They could then shave with both razors and see if they can tell a difference and correctly identify the un-stropped razor.

Thoughts on any of this?

Joe

Let us know how it goes after your 15 shaves with each razor. My guess is that you will not need to send them out for a second opinion.

Glen

He seems to be talking about sharpening effects of a strop. Those are indeed negligible. That's not why we strop though (unless you're talking stropping on an abrasive-impregnated strop). We strop to align the edge, not to remove metal (i.e. sharpen).

daveesq said:

He seems to be talking about sharpening effects of a strop. Those are indeed negligible. That's not why we strop though (unless you're talking stropping on an abrasive-impregnated strop). We strop to align the edge, not to remove metal (i.e. sharpen).

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I second that.

X

Well lets see here this is a difficult one, one the one hand many many millions of men have shaved with straights over the years and have found stropping to be effective and one guy with a degree comes along and tells us all those guys were wrong, imaging things and he's correct. I think that says it all.

I don't think most modern metals are that much harder than most vintage steels used. They all fit into the same range. Its just a few of the most recent steels that are a tad higher. Also its true he's talking more about sharpening which a plain leather strop does not do which he seems not to have figured out.

You want to do a stropping experiment? Go over to SRP and do a search under The Grand experiment and you'll see it has already been done.

I.m with BigSpender on this one. One guy with a "scientific" post negates the results of thousands who do this daily and know the difference between a stropped and non-stropped blade.

Reminds me of the Boone article which in many cases flies in the face of what actually works for most of us.

I read a lot to learn what others have experienced but really only rely on my own empirical results. If it works it works.

Tony

I hate that article but I agree with him on this. He is merely proving that leather, though known to have "abrasive" qualities, really doesn't. In fact it doesn't hone at all. I think that is the point of his observation.

Again, as mentioned, I think at best the strop simply helps align the edge because of a "stickiness" within the leather itself.

I, for one, rarely strop. I just let my blades rest and they shave fine. But, I have no intention of getting rid of it.

I bet you'd have to shave with an edge though to sense any improvement that might be observable. I would think the disturbance is pretty light.

I believe the strop acts on a straight razor as a steel does on a chefs knife. The purpose is not to hone or even polish the edge, both of which involve removing metal, but rather to realign the edge. Correct stropping should help maintain a good edge, but will not fix a bad one. Hence the occasional need to tune the razor on a pasted strop or finishing hone.

Education is no proof against category errors.

What kind of sharpening did they do on these blades?

The last quote in Joe Perri's original post mentions a 1000-grit wheel, and a 200-grit wheel. If this is what they used for honing, instead of 8000-grit or finer, then the edge they ended up with, and did the experiments on, has little in common with the edges we shave with.

Now as for how stropping 'aligns' the blade: If 'alignment' is something that really happens, then it should be visible under a microscope. I've looked at my edges under my Radio Shack 100-power microscope, and haven't seen the teeth that supposedly get aligned. I've seen smooth edges, and I've seen rough edges, but can't tell anything about the alignment.

Don't get the wrong idea, I think that stropping is doing something that makes a difference. I just think that I need a stronger microscope to tell what it is.

The image I have is that the edge of a straight razor which has been used for shaving looks like the back end of an airplane wing, with lots and lots of little flaps. Some of the flaps are pointing up or down, and stropping will either align them with the wing surface again, or break them off. In either case they won't interfere with the edge slicing through the hair the next time you shave. If you didn't strop, these flaps would catch on the hairs and result in more tugging than necessary.

I may be wrong, though.

/Nicholas

Magruder said:

What kind of sharpening did they do on these blades?

The last quote in Joe Perri's original post mentions a 1000-grit wheel, and a 200-grit wheel. If this is what they used for honing, instead of 8000-grit or finer, then the edge they ended up with, and did the experiments on, has little in common with the edges we shave with.

Now as for how stropping 'aligns' the blade: If 'alignment' is something that really happens, then it should be visible under a microscope. I've looked at my edges under my Radio Shack 100-power microscope, and haven't seen the teeth that supposedly get aligned. I've seen smooth edges, and I've seen rough edges, but can't tell anything about the alignment.

Don't get the wrong idea, I think that stropping is doing something that makes a difference. I just think that I need a stronger microscope to tell what it is.

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Through the radio shack microscope? The quality of the optics in the RS unit might be great for checking for chips and gross problems in the blade but to see the fins on the edge you would need a very high quality microscope with several hundred if not thousands of diameters to see those.

It is interesting to see the different responses from everybody. It seems that this is a controversial topic. I'm sorry if I'm causing bad feelings, that was not my intent. Nor was it my intention to use an appeal to authority. I just thought this was a pretty neat study and wanted to talk about it.

As to the specifics, it seems that the common belief is that stropping does not sharpen or otherwise improve the edge but re-aligns the edge some how. The edge is supposed to be comprised of "teeth", "flaps", "tabs" or bent sections that need to be re-aligned to maintain shaving comfort. This is certainly possible but not supported by the micrographs of the edges. Here is a micrograph of a straight razor edge:



The edge seems to be smooth with no bur, flaps, tabs, teeth or other structure than could easily bend and create this need for re-alignment.

Some of the edges that were tested with the plain strops were formed with 6000/8000 grit Japanese water stones, others with a 1000 grit tormek.

I did search out the Grand Experiment but that was a single sided, sighted experiment. A blind study is needed to remove any bias. I'm really interested in trying a blind study of this. Would anyone else be interested? I'm certainly very open to the collected wisdom and experience of many generations of straight razor shavers and can readily accept that stropping does affect the edge in a positive way, I just see some strong contradicting evidence that I'd like to explore.

Joe

JoePerri said:

It is interesting to see the different responses from everybody. It seems that this is a controversial topic. I'm sorry if I'm causing bad feelings, that was not my intent. Nor was it my intention to use an appeal to authority. I just thought this was a pretty neat study and wanted to talk about it.

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Speaking just for myself, there were definitely no bad feelings. Yes, it's a controversial subject, because there's little hard data to go on. And what data there is, such as the study you mentioned, seems to contradict our own experience.

For example, I can get different results on the thumbpad test and the hanging hair test after I strop. So something changed on that blade. I don't know what, and I don't know how to tell, but it's different.

were those micrographs taken before or after shaving? It seems that the general consensus is that shaving disaligns the edge, and stropping fixes it.

Wow, neat pictures. Am I right in reading that they are at the 10 micron level? Would you need to magnify down to the 1 or 2 micron level to see teeth? I'm not sure so I'm asking.

Also, one of the quickest ways to answer your question is to shave with a razor for as long as you can without stropping. When it pulls or gets too uncomfortable strop it and see if it makes a difference. You will then have your answer.

Chris

EL Alamein said:

Wow, neat pictures. Am I right in reading that they are at the 10 micron level? Would you need to magnify down to the 1 or 2 micron level to see teeth? I'm not sure so I'm asking.

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They are pretty neat! They are taken at 800x and 3000x. The smallest resolvable feature in the 800x is less than 1 micron and around .1 micron in the 3000x.

I am planning on doing a simple trial as you suggest but since it would not be blind my bias could certainly creep in.

Are there any experts willing to take part in a blind experiment? I'd sure like to give it a go. My plan is to buy three identical razors. I'll send all three to an expert honemeister for an identical sharpening. I will then shave for 15 days with each razor, stropping one or two but leaving one or two unstropped. (In other words there could be one stropped blade and two unstropped OR two stropped blades and one unstropped. It is important that the expert not know.) I will then send all three to an experienced expert straight razor shaver and have him use all three blades in the condition they arrive in. The expert would then identify which razor(s) gave the best/smoothest shaves and also which two were the matching pair. This is a standard ABx or triangle test. If the expert is unable to correctly identify the matching blades the difference is said to be undetectable. If he correctly identifies the matching pair and the unstropped razor(s) then we would say there is a noticeable difference. We could then repeat with 2 or 3 more experts.

Any one want to participate?

Joe

http://mse.iastate.edu/fileadmin/www.mse.iastate.edu/static/files/verhoeven/KnifeShExps.pdf, for the interested.

No takers on the experiment?

Anyone with a few years of straight razor shaving experience will do.

Joe

Men have been stropping blades for hundreds of years. I think most would agree that stropping does something! Either that, or you've found the biggest placebo effect in history.

What this paper shows is that the action of the strop, whatever it is, is nonabrasive, and likely at a submicron level