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Holding An Edge (Stropless Shaving)

The blade edges in my first M7DS are now approaching perfection so I am thinking of a new challenge.

I have two SR's that are effectively identical except for their steel hardness, so I am thinking about trying to determine how important is steel hardness when it comes to a blade holding its edge. These two SR's are:
The edges of both of these SR's provide very similar shave results and comfort, even when doing a Fool's Pass (FP). They have both been maintained only with 60 laps on the same clean leather strop before each shave and 60 laps on the same 0.1um diamond pasted hanging balsa strop after each shave. Each blade is oiled in between uses to reduce any corrosion effect.

I intend to first determine the edge holding ability of the T.H.70. To do this, I will alternate between each of the two razors for each day's shave. The T.H. 60 will receive its normal maintenance while the T.H.70 will receive no maintenance (no leather or balsa stropping) except for oiling. Pre-shave prep will remain the same for each shave. Once the T.H.70 becomes noticeably less comfortable to use compared to the T.H. 60, I'll call it quits with the T.H.70.

Once the T.H.70 is done with, I will swap it out for another T.H.60 that I have that shaves as well as my reference T.H.60 and repeat the process.

Results will be posted in this thread.

Looking to start this little experiment next Monday. Are there any suggestions for improvements?
 
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I'd say that dropping the .1µm diamond on the T.H. 70 and giving it 60 on just leather before and after each shave would be more relevant as it is closer to what the vast majority of straight shavers do. Add 20 linen per shave and you could be normal. :001_rolle You would be comparing normal maintenance to method maintenance.

It is your experiment though, so do whatever you like.:punk:
 
I think this is going to be a short test, you, like me, are spoiled by having an excellent edge every time you use the pasted balsa after a shave.

Curiosity has led me to do a HHT test after a shave, and most razors are barely able to chop a hair after a shave. Same razor after stropping on leather passes with flying colours. Proves to me that short term, stropping on balsa is not essential, but stropping on leather is.

Going to the balsa, then the leather can theoretically maintain an edge indefinitely, but with no stropping I can't think you will get more than three shaves before things go south drastically.

Some experts even strop between passes.

Good luck, eagerly awaiting the results.
 
I'd say that dropping the .1µm diamond on the T.H. 70 and giving it 60 on just leather before and after each shave would be more relevant as it is closer to what the vast majority of straight shavers do. Add 20 linen per shave and you could be normal. :001_rolle You would be comparing normal maintenance to method maintenance.

It is your experiment though, so do whatever you like.:punk:
The idea of this little experiment is to get an indication as to how much the steel hardness affects edge-holding ability, not so much comparing use with and without pasted balsa stropping. Others here on B&B have found that they can get 50 to 100 or more comfortable shaves out of an edge with clean leather stropping only. That takes months to determine.

Trying to compare using balsa stropping -v- not could take months before I got a result. First I'll try it without any stroppping for faster results. Late, if I am so inclined, I might also try the loooong method.
 
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I think this is going to be a short test, you, like me, are spoiled by having an excellent edge every time you use the pasted balsa after a shave.

Curiosity has led me to do a HHT test after a shave, and most razors are barely able to chop a hair after a shave. Same razor after stropping on leather passes with flying colours. Proves to me that short term, stropping on balsa is not essential, but stropping on leather is.

Going to the balsa, then the leather can theoretically maintain an edge indefinitely, but with no stropping I can't think you will get more than three shaves before things go south drastically.

Some experts even strop between passes.

Good luck, eagerly awaiting the results.
I agree that it will probably be a short experiment. That's what I would like. I would like to have this experiment complete within a week or two.

From what I have read elsewhere, most are lucky to get 2 or 3 reasonable shaves out of a HCS edge without any stropping. HCS blades normally have about 60 RHC. I am looking to see if the T.H.70 with a hardness approaching 70 RHC gives more and by about how much.
 
The biggest problem I see is that your sample size (one) is so small that you can't make any valid conclusions.
What happens if you used a 70 RHC blade that was defective in some way or the HCS was unusually hard? Have you measued the hardness yourself or take the manufacturers word? If so, how much does the manufactured product vary in hardness? etc etc

Normally you would have a number of 'samples' so that you could cover variation and uncertainty about the result and express the answer with say a 95% confidence interval.

The other issue is that you are measuring the variation between two different populations. You are comparing the change in an un-stropped stainless blade against a stropped HCS blade. Would it mot make more sense to compare Stainless steel unstropped vs a HCS unstropped, in that way you are only measuring the impact of steel type/hardness? By stropping one and not the other you are testing for steel type & strop influence.

But seeing that this a bathroom experimepnt, do what ever makes you happy. I'm no expert in this area, and am still interested to see your results.
 
The biggest problem I see is that your sample size (one) is so small that you can't make any valid conclusions.
What happens if you used a 70 RHC blade that was defective in some way or the HCS was unusually hard? Have you measued the hardness yourself or take the manufacturers word? If so, how much does the manufactured product vary in hardness? etc etc

Normally you would have a number of 'samples' so that you could cover variation and uncertainty about the result and express the answer with say a 95% confidence interval.

The other issue is that you are measuring the variation between two different populations. You are comparing the change in an un-stropped stainless blade against a stropped HCS blade. Would it mot make more sense to compare Stainless steel unstropped vs a HCS unstropped, in that way you are only measuring the impact of steel type/hardness? By stropping one and not the other you are testing for steel type & strop influence.

But seeing that this a bathroom experimepnt, do what ever makes you happy. I'm no expert in this area, and am still interested to see your results.
The hardness of both blades had been measured locally. The manufacturer claims about 60 RHC for the T.H.60 (I got 59) and about 70 RHC for the T.H.70 (I got 68).

I am comparing both a T.H.70 un-stropped blade and a T.H.60 un-stropped blade against another known T.H.60 blade that receives normal maintenance. All three blades are currently giving about the same quality shave. Unfortunately I do not (yet) have an abundance of the same blades to average out the results. Maybe when I get a few more M7DS's.
 
Please remember that the purpose of this exercise is not to test how many shave can be obtained from a single edge without stropping. That is covered here:

In this exercise is to get an idea as to how blade hardness affects edge retention.
 
Please remember that the purpose of this exercise is not to test how many shave can be obtained from a single edge without stropping.

In this exercise is to get an idea as to how blade hardness affects edge retention.
While I will be following this thread with interest, does it really matter?

One of my best razors, as far as longevity of a good shaving edge between honing, is a no name razor that just says 'The Winner' on it. It is fairly soft, judging from how easily it honed, and I attribute it's 131 shaves to how well the relatively soft steel responded to the hemp and leather strops.

So, if stropping before and after shaving is the norm, and stropping a softer steel results in maintaining the edge for a roughly equal number of shaves as harder steels...

Anyway, carry on. I'll be interested in your results.
 
I attribute it's 131 shaves to how well the relatively soft steel responded to the hemp and leather strops.
Interesting! I imagine it's not as much how it responds to the strops as how resilient it is to chipping: Perhaps the softer steel bends rather than breaks so while it may not shave as much without stropping, less permanent damage is done to the edge. Is there a rating for the ductility of an alloy eg. how well it resists breakage? Maybe we should be looking at that as well as hardness, with the goal of being just stiff enough to retain sufficient keenness to get through a single shave while having maximum damage resistance?
 
Interesting! I imagine it's not as much how it responds to the strops as how resilient it is to chipping: Perhaps the softer steel bends rather than breaks so while it may not shave as much without stropping, less permanent damage is done to the edge. Is there a rating for the ductility of an alloy eg. how well it resists breakage? Maybe we should be looking at that as well as hardness, with the goal of being just stiff enough to retain sufficient keenness to get through a single shave while having maximum damage resistance?
There is a measured property called toughness in metallurgy. As a metal fatigues micro cracks start to propagate which lowers the toughness, but the yield strength also increases as the metal work hardens. It gets complicated when we consider that there isn't a consensus on what sharp means and how to measure it. I think that it is generally accepted that an edge dulls by microchipping gradually increasing the radius of the apex until it is large enough to effect the cutting performance. I'm still of the belief that stropping is primarily an abrasive operation.
 
I'm still of the belief that stropping is primarily an abrasive operation.
Very interesting! Thanks, I'd been thinking about it as bending back into place, but this perspective that it's more about knocking off the bent bits and generally cleaning up the edge with some fine abrasion makes sense of your comment about the soft steel responding better to the strop. Is this still a matter of belief, there isn't any conclusive work that has nailed down what the mechanism is?
 
While I will be following this thread with interest, does it really matter?

One of my best razors, as far as longevity of a good shaving edge between honing, is a no name razor that just says 'The Winner' on it. It is fairly soft, judging from how easily it honed, and I attribute it's 131 shaves to how well the relatively soft steel responded to the hemp and leather strops.

So, if stropping before and after shaving is the norm, and stropping a softer steel results in maintaining the edge for a roughly equal number of shaves as harder steels...

Anyway, carry on. I'll be interested in your results.
You raise an interesting point that I hadn't considered - clean leather stropping more easily resharpening an edge of softer steel. I might look into that once this first "hardness test" is over.
 
Is this still a matter of belief, there isn't any conclusive work that has nailed down what the mechanism is?
On the nay side SEM images don't show much evidence of abrasion. The old barber manuals always talked about 'aligning the fin' etc.

On the yeah side. Many people talk about strop grit in the 50-80k range. We know that leather will remove and polish steel, removing patina and iron oxide. People used to hang weighted leather straps on line shafts and it kept the shafts bright and polished. Some forms of iron oxide are definitely abrasive (jewelers rouge) about .1 µm. So as your strop is cleaning iron oxide off of your razor the razor is charging the strop. Caveat, there are many forms of iron oxide and I'm not sure that they are all abrasive, but it seems likely.
 
And what if you strop it using just a jeans leg....., does it work....and for how many shaves....
Let us know when you’ve completed your test!


On the nay side SEM images don't show much evidence of abrasion. The old barber manuals always talked about 'aligning the fin' etc.

On the yeah side. Many people talk about strop grit in the 50-80k range. We know that leather will remove and polish steel, removing patina and iron oxide. People used to hang weighted leather straps on line shafts and it kept the shafts bright and polished. Some forms of iron oxide are definitely abrasive (jewelers rouge) about .1 µm. So as your strop is cleaning iron oxide off of your razor the razor is charging the strop. Caveat, there are many forms of iron oxide and I'm not sure that they are all abrasive, but it seems likely.
Interesting concept of the razor charging the leather. Iwasaki mentions not cleaning the secondary (fabric) unless it becomes contaminated. The following quote is from the section on linen.

‘Through use, the strop will blacken with steel particles from your razor. When it blackens, its polishing power increases, so I recommend you keep it that way carefully.’
 
This little adventure has now started.

I have decided on using the following SR's:

Titan ACRM-2 T.H.60 (Solis). This is from my M7DS and will be my reference razor. This razor will receive 60 laps on clean a leather strop before each shave, 10 laps on a clean denim stop after, followed by 60 laps on 0.1um hanging balsa strop before being oiled and put away.

Titan ACRM-2 T.H.60 (Vesperum). Measured hardness of 59 RHC. This well receive 60 laps on a clean leather strop before first use, then no maintenance before or after use except wiping clean with paper tissue and oiling before putting away.

Titan ACRO T.H.70 (Evening). Measured hardness of 68 RHC. This will receive 60 laps on a clean leather strop before first use, then no maintenance before or after use except wiping clean with tissue paper and oiling before putting away.

This morning (Sunday) I shaved with Solis. That gives me a reference from which to judge. Monday and Tuesday will be Vesperum and Wednesday back to Solis. Each shave will consist of two passes, WTG and XTG, and a Fool's Pass to test the edge

If Vesperum is still acceptable, I will then alternate between Vesperum and Solis until Vesperum fails me. Failure will be if the edge does not perform the Fool's Pass with comfort.

Once Vesperum fails me, I will start the sequence again with Evening in place of Vesperum.

All this should work well for Solis as it is the newest SR in my M7DS and needs a few more shaves to match the wear of the other six in its set.

The only little glitch is that I will not have Solis available for Thursday and Friday this week as it will be away getting engraved. This shouldn't be a problem that I can't work around.
 
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