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What Does Stropping DO ?

Of the papers I've read from Dr. Verhoeven's studies the stropping was done on a spinning leather wheel and compared a loaded chromium wheel to plain leather. Thus, showing the plain leather added no refinement to the edge but the loaded wheel did. Thanks, Possum

Mr. Parker, Read exactly what I wrote, I'll quote it again for you: "Of the paper I've read..." I was not saying 'your' paper. I was meaning this paper;
http://mse.iastate.edu/fileadmin/www/mseiastate.edu/static/files/verhoeven/knifeShExps.pdf
Where he examples several types of leather wheels for stropping and the more common stationary type. All the accompaning photos show how little affects the plain leather had on the steel. While the loaded strop had much affect at refinement and burr removal. (different slurries used) Alfred Pendray
an accomplished Master Bladesmith did the stropping on the running leather wheels. (around pg.29) We maybe closer than you think... I'm just saying plain leather has 'some' affects. We already agree a loaded strop has much more affect on the steel. While some of Dr. Verhoeven's findings strike against, shavers normal pratices its hard to argue with a camera. So, load them strops up boys we're going to do some shaving! Possum


We are both talking about the Verhoeven paper, but we're talking about different parts of it. He uses both leather disks and flat leather strops in different chapters.

I agree that the leather strop has some effect. When I strop on linen, I must strop on leather afterwards in order to get a good shave. However, I'm saying that I don't know what those effects are, except that (a) they're beneficial and (b) I'm pretty sure it doesn't involve straightening out imaginary teeth in the edge. Hopefully someday some intrepid member with access to a SEM will perform similar experiments using a traditional straight razor and strop.
 
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Oh and Mparker, they aren't teeth in that way we visualize them, they are just functionally like them. As you said, the edge is torn away. However, if you were to make a topographical map of the edge with the zero plane being the hypothetical "ideal" high point of the bevel (on either side). When you hone the opposite side of the bevel, and metal is abraded away, what you might call "odd" metal is pushed up into your plane (the bevel not contacting the hone) becoming topography. Now since metal isn't fluid at the temperatures we're at, this obviously isn't going to act is if it were cast steel... so the strop doesn't need to abrade it. It contacts the plane (bevel) at a structurally weak point. So we strop to gently push it back in line, avoiding ripping it off and degrading the edge. That's the "teeth". Not just gouges with perfect little plowlines between them as low grit bevel scratch patterns make some people visualize. Fortunately, for the sake of realigning these "teeth", it doesn't matter how you visualize it. What matters is that they are connected to the blade by fatigued steel and can be pushed back into alignment.

It works like that at coarse grit sizes, but doesn't seem to work like that at the very fine particle sizes that concern straight razor shavers. Take a look at the 10,000x SEM photos in the Verhoeven paper, in particular the shots of the Gillette and straight razors on pp 6-7. There's nothing resembling what you've described. However, when looking at the shots of edges honed at 600 grit or so then your description does seem to match what shows up under Verhoeven's electron microscope.
 
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Agreed, Verhoeven does not say he stropped 100 times as some here do. You bring up a good point going to the linen first then a lot of hand stropping on plain leather would have some affect and give a good shave for what ever reason. The same procedure w/ stropping on chrome oxide would give better refinement and hence a better shave w/ less work and the reasons presented with evidence. Possum
 
It works like that at coarse grit sizes, but doesn't seem to work like that at the very fine particle sizes that concern straight razor shavers. Take a look at the 10,000x SEM photos in the Verhoeven paper, in particular the shots of the Gillette and straight razors on pp 6-7. There's nothing resembling what you've described. However, when looking at the shots of edges honed at 600 grit or so then your description does seem to match what shows up under Verhoeven's electron microscope.

I see exactly what I described. It's less obvious in the pg 7 image because that edge has been stropped. Look at the pictures on 19 and 20. It might be noted that he chose to use a butz strop (Suede) when "proving" that uncharged strops have little effect despite having used hard leather to initially strop the razor for the page 7 pic. He also draws conclusions based on images that he mysteriously doesn't include and notes that the evidence he's basing his conclusions on was much more noticeable in these secret pictures.


He also declares that a 6k waterstone is superior to Ceramic stones because he couldn't take his razor from 600 grit to a shaving finish in 40 passes on a barbers hone with a note that additional tests are required to confirm this. (Yeah, I should think so).
 
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Agreed, Verhoeven does not say he stropped 100 times as some here do. You bring up a good point going to the linen first then a lot of hand stropping on plain leather would have some affect and give a good shave for what ever reason. The same procedure w/ stropping on chrome oxide would give better refinement and hence a better shave w/ less work and the reasons presented with evidence. Possum

He stropped 40 times on a short (8" iirc) Suede strop.
 
Slice, Good--we needed a eye from a different slant to read some of this inorder to call some points to our attention. I've read that paper several times and never caught what you just did. According to my grit charts the 6k JIS waterstone is the same as a ultra fine ceramic (ANSI). But all charts are not without error. I'm thinking a harder, better quality leather strop would have made more difference on the edge. But as much as the slurry applied strop? I doubt. Still, that would lend some explaination as to why a good shave can be had using a plain leather strop. There could be some plastic flow on the thin edge of a razor. Thanks guys, good discussion. Possum
 
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For some reason I read his "Ultra Fine" as a barber hone.

http://www.razoredgesystems.com/pro...lvm_fly2_grey.tpl&product_id=11&category_id=6

It appears this is the hone he used. I doubt it's the grit of a vintage Ceramic (The "official" grit of ceramic hones dates back to the 60's at least. I've seen it in a couple books I don't have on hand at the moment (Library) that rated Ceramics, Diamond hones, and Arkansas against each other on a grit scale.) That said, I can only find one reference about the stone outside of the manufacturers site, and given the price and how long they've been around (a decade at least). I would guess that judging ceramics as a whole based on that stone is a very bad idea. Anyway, just something that makes me doubt this guys expertise. The pictures are nice and all, but when I was at college I could probably have gone into a lab with SEM's and done something like this in an afternoon or two. Just because he's a professor and he's got access to this equipment really doesn't convince me that he knows what he's talking about.
 
The first link MParker gave (Modern Mechanixs) does say stropping bends the jagged edge back into a more uniform position and shows photos. Plus, discusses more about how tough a beard is for a razor to cut and how whiskers damage the edge. All this is repaired by stropping. The author Mr. Martin does not say how much stropping is required but appears to be using a normal strop like a Illinois. Possum
 
So....

If the effect is 'aligning of teeth', why do we need a soft, conformal surface like leather to this? Why does a 'stropping' motion on a hone not do this? (And...it doesn't, as far as I can tell).
 
So....

If the effect is 'aligning of teeth', why do we need a soft, conformal surface like leather to this? Why does a 'stropping' motion on a hone not do this? (And...it doesn't, as far as I can tell).

The stropping surface must be compressible.
 
But wouldn't a thin band of steel do the identical thing? I mean something on the order of 0.010" thick (.25 mm for the metric types). ?? The steel could not bend to a zero radius and so would lift away from the bevel and again only touch the last few millionths of the edge.

Brian

The compressibility of the strop allows it to act on the very edge of the blade (the last couple of microns).
 
If it could have that level of flex and not rip when held taut enough that you could force it to not remain flexed (translating force applied downward to the band (as to a strop) to "straighten it" against the edge which is trying to bend it into force applied against the edge to resist its attempts to bend it) then I imagine it could work. But I doubt steel could be worked into this state.
 
Well, twenty thousandths is just a number I pulled out of the air. But using that as a working number, a piece of mild steel, 3" wide X 0.020" thick would have a tensile strength of 3,600 lbs. I doubt that would rip or tear even if held in gorilla hands. :)

But something more commonly used as a strop, newspaper, does not effectively compress and yet works as a strop for all the same reasons: it is thin enough to flex as the blade passes over it and yet cannot make an infinitely small radius (which causes the paper to lift away from the bevel. Paper is, for all intents and purposes, non- compressible.

I think anything that will flex around the radius of the edge and rub against it at an angle greater than the natural caused by the bevel will work as a strop. Of course some materials will work better than other material but I think they will all function.

Brian

If it could have that level of flex and not rip when held taut enough that you could force it to not remain flexed (translating force applied downward to the band (as to a strop) to "straighten it" against the edge which is trying to bend it into force applied against the edge to resist its attempts to bend it) then I imagine it could work. But I doubt steel could be worked into this state.
 
A stack of newspaper doesn't compress? I'm not too familiar with stropping on print, but I believe newspaper compresses pretty well. I'm surprised the tensile strength of steel is that high at that thickness, maybe get some steel foil and try it out? If you point me somewhere to get 2/100ths" thick steel bands for cheap, I'd be game to try it out. I have pretty high standards for strops and believe I could get a pretty good read on its efficacy compared to traditional linens and leathers.



This look like the right stuff?

http://www.staples.com/PRECISION-BRAND-100-in-L-Low-Carbon-Steel-Shim-Stock-6-in/product_711698
 
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OK, I just stropped a shorty that I don't normally shave with on smooth galvanized .017" steel. Surprisingly, it did not feel as ridiculous as I expected.

After about 20 laps I checked HHT = no HHT, but I did not know its condition before the stropping.

Brought the edge up to HHT 4 with CrOx, clean denim, leather, then another 30 laps on the galvanized steel. HHT was worse but not completely absent. I do not believe that HHT is completely objective, so I cannot state definitively that the steel degraded the edge.

This is an interesting discussion. I do find it odd that leather stropping is ubiquitous, and so many very different leather surface conditions produce good results.
 
Other than some alignment of the metal. What does stropping do? Is it micro plastic flow at the edge? When we know that steel is much harder than plain leather . I realize whats going on when slurry is applied but with out slurry. Possum

Stropping removes any debris from your blade prior to shaving. After honing, it removes any loose metal fragments. Before or after shaving, it removes any soap or water debris.
 
The blade only needs to sink in a few microns, so only the outer surface needs to be compressible, not the bulk of the strop.

Newspaper is sufficiently compressible, and I expect the print is abrasive as well.
$newsprint.jpg
 
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