Sharpening razors — old wives tales?

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bushtucker

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I'm putting this in the Maintenance area because the razors area seems to have low traffic and because the behavior of steel is not specific to razors.

The issue is one of "resting" the blade between uses so that the edge can "slowly grow" back into shape. I have never heard of steel slowly reforming itself, and I want to check here with the experts to see that the score is. See the references below:

DOVO website FAQ said:
There is no generally valid rule for the whetting (stropping) of straight razors; in many cases, it is sufficient to draw the razor lightly over the ball of the thumb, especially when it has been left unused for several days between shaves. Wet shavers of the old school know that the facet (blade) "grows", i.e. the microscopically discernible and extremely fine "fin" on the cutting edge changes during the shave but returns to its old position afterwards; it stretches and again becomes extremely fine....straight razors are whetted in the factory for use (whetting on leather by hand). If you own a suitable strop, you should nevertheless take into account that the razor must first "rest" after use. After the razor has been carefully rinsed and dried, it should not be used again for at least 24 - 48 hours because the fine "fin" on the cutting edge straightens up again extremely slowly
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mu1014w.jpg
 
kershlack said:
I may not be correct at all, but here is a mildly educated guess.

In the time of blades that looked like that above there was a significant silver content in them. Silver is naturally a very soft metal in which it probably would be possible for a resting blade fill itself out again.

Again that is probably not correct, but it could be.
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No, straight razors are still made and sold today, and this has nothing to do with antique blades or silver.
 
I'm a str8 user (Dovo Special) for about the last 6 months. I'm always experimenting and trying to judge "cause and effect". I haven't experienced anything to suggest the phenomena from the DOVO website is an important factor.

By the way...if you love sharpening knives and using stones, you'll love shaving with a str8. It is a sharpening addicts dream. The honing angle is set by holding the blade flat to the stone. You get to fool around with 4K, 8K, 12K, or even 16k stones and pastes. You use the razor evey day and strop it every day too! After a few months of so-so results, you start getting really nice shaves.
 
No, you're basically shaving with a very thin, hard, sharp piece of steel.
Bill
 
Bill DeShivs said:
No, you're basically shaving with a very thin, hard, sharp piece of steel.
Bill
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AMEN!

And a leather hone loaded with .5 micron diamond before final stropping on the barber strop will let you get to know just what SHARP really means! :):)
 
Burr or no burr, who cares? The "extremely fine "fin", as described by Dovo, sounds like a burr, or wire edge, of sorts.

What's the deal with letting a razor rest? Sounds like BS to me.
 
Scientifically, it's supposed to have something to do with the Bauschinger effect, the elasticity of steel, hysteresis and strain aging. If you are interested, you can follow the debate here.
 
bushtucker said:
Scientifically, it's supposed to have something to do with the Bauschinger effect, the elasticity of steel, hysteresis and strain aging. If you are interested, you can follow the debate here.
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This is true, also every material has some elasticity to a certain point only before it reaches a point where it only has some degree of elasticity and further that point will lead to a break of material.
Most of metals (90%) in solidification cristalizes to 3 compact cristalin structures, 2 forms of cubic and 1 form of hexagonal and it is the strengh in certain material at certain temperature that will dictate the tension needed for elastic and non-elastic nominal tensions.

so it will have some elasticity, but saying what dovo stated without providing some specific data, like the tension used in shaving to NOT reach the non-elastic treshold in the tiny cristalized structures at the tip just makes no sense! It will also make no sense if they provided because in pratical world there was no way to measure it.

It is true that also the timming for the metals go again to it's initial form when they are in the elastic range, it is slow, but heck... did they studied their particular model and shaped straight razors along with their specific metal type arrangements to reach a specific conclusion? I don't believe so. It is too costly and it had no big interest for them to know exactly that.

The point is, that it is true what they state, within some variants, but not true in others. There is no way they can tell that without kowing the tension caused by a particular person shaving fo eg, and assume that they only caused elastic tension, and extrapolate that to a average time wait... scientifically it is true in some extent, but it cannot be extrapolated to real world like this.

IMO, just don't think about it too much to the point where it interfieres with your daily life, because it just don't worth that time lost. Just strop it, when you need to and when you can. It is like sharpening and stropping a knife and go check to a electonic microscope to see if it has reached it's peak in sharpness... no interest in real world.

If you ask:
-It will be better to wait? YES from a scientific standpoint, not a pratical one
-Will that make a huge diferrence? Probably NOT
-Will it worth loose time thinking about this detail? Definitly NOT.
Your life do not last forever, when the razor is consuming you too damn time just buy another and move on.


EDIT:

Just to add, some users rotate their razors, and that's a good way to have the best of both worlds. Just don't buy another on purpose for this, it's far different colleting them because you like it and rotating them from buying just for this; makes no sense.
 
bushtucker said:
Scientifically, it's supposed to have something to do with the Bauschinger effect, the elasticity of steel, hysteresis and strain aging. If you are interested, you can follow the debate here.
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Scientifically, it's to do with getting men to buy more razors. IF you've got to let your razor "rest", you need another. If you have to let it rest a week, you need seven.
 
dscheidt said:
Scientifically, it's to do with getting men to buy more razors. IF you've got to let your razor "rest", you need another. If you have to let it rest a week, you need seven.
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That's the point where people have to think and reasearch the scientific standpoints and see if they make sense in real world. They are correct at some degree, but that was obviously wrongly marketing manipulated to reach the point they want, and you are damn right, it is just to justify or impel the average joe buying more razors.
 
darklight said:
That's the point where people have to think and reasearch the scientific standpoints and see if they make sense in real world. They are correct at some degree, .
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No, it's ludicrous. Steel that's elastically deformed doesn't take days to return to shape. It just doesn't happen. There's a reason the only cites for the effect in question are marketing materials from a razor company.
 
When I said they are correct to some degree, meant that it does happen in metals.
What I didn't said, and you assume I did, was that it does happend in the timming they said and to their specific sized metals.

dscheidt said:
Steel that's elastically deformed doesn't take days to return to shape.
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You generalizing way too much.

How can you base your conclusion on, without even a deforming tension and don't even know the steel?
If you deform near the plastic deformation point, it will take more time to recover that it would if it was applied a small tension relative to material.
From trials in traction machines considering the charge cell stands and the provete moves away, 17-7PH stainless stell will need near 1300 MPa of tension before reach plastic deformation, a 2024-T81(non-coated) aluminium sheet will need less than 400 MPa that is almost 3 times less.... (graphic based analysis).
So how can you then assume that the timmmings to reshape are the same for all and generalized?

They will derform, and it will take time to re-shape, and that time will depend on mass, temperature, gravity, geometry of the steel, etc...
So it is not possible to say for sure how long will it take. It can be instantaneous or it can take a lot of time.
Most of the time it will be fast like maybe a straight razor edge, but a bridge of stell that went trough a earthquake and did not rech the plastic deformation will take a lot of time to take the initial shape.

Timming for elastic deformation reshaping is not very studied because it is not very usefull in engeneering.

dscheidt said:
There's a reason the only cites for the effect in question are marketing materials from a razor company.
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The effect in question, is calculated by the young's module (E=σ/ε) and that formula has has at least 180 years old.

I gave my opinion on this particular object in the earlier post, it worths what it worths - specially the qustion/answer, and discussing beyond that will lead to nowhere, even if it lead it doesn't worth my time nor the benefits of the conclusion.
 
Now this is about as UNscientific as you can get. But interesting!:D

The barber shop that I use has 5 barbers. One under 30 (I think) and the rest over 60. I asked if they allow their razors to "rest."

They all looked at me like I was nutz, and one said "whadda ya mean rest?" :confused:

Now, these guys may not be professional razor sharpeners, but they are professional razor USERS!:p
 
It's interesting that people quote a paper written over 100 years ago. We have today electron microscopes that are capable of magnifications of 1 million times !!! We can see things today not even guessed about 100 years ago ! My grandfather used a straight razor and did have a set of razors . But that's in the old days. THIS metallurgist uses a disposable razor and I have seen an interesting progression of technology in my lifetime.Carbon steel - stainless steel - platinum plated - teflon coated - one blade - two blades - three blades -four blades - lubricated blades .I might have forgotten a few. I'd like to see time/lapse video of a burr straightening out by itself ! Let's not have any more speculation ,non-scientific drivel and do a proper study.
 
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