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Disposable Razor Maintenence
#11
(02-07-2019, 12:10 AM)grepper Wrote: Mr. Mark, are you actually saying you get your legs silky smooth with a straight?  No worries about unattractive nicks on your shins? 5arg   I just hate it when that happens!

I have a toy razor that is getting on the dull side.  I'll throw it under the scope and try to see why it's dull.  I find it hard to believe that just shaving could actually wear the edge down. Maybe corrosion?  Unless the blade is cutting sandpaper or some other abrasive, isn't dulling pretty much synonymous with rolling?  I guess an edge could be mashed straight down, but from my limited experience there is more proclivity to roll than to mash.

Nicks on my legs? Heavens no. I wax.

We just have a difference of opinion at the moment, Mr. Grepper. Wear and corrosion seem much more likely than rolling (or mashing) the edge of a razor blade IMHO. I think the biggest difference between your experience and mine is that you mainly use softer stainless and I mainly use hard carbon steel. Our expectations can not be the same.

Our friend Larrin, The Steel Nerd, has written reams about edge retention, edge stability and wear resistance of lots of different steels. I believe he uses a CATRA machine, which would be the fanciest way to dull a knife. I don't remember hearing that the CATRA machine rolls any edges. The next best edge retention test is cutting rope, and I haven't observed edges rolling from cutting miles of rope either. 

I believe rolled edges to be plastic deformation, so once an edge is rolled it has to be "unrolled" if it's going to keep cutting. Meat processing blades are the ideal example, but they're also very specialized. The soft stainless rolls and gets unrolled every 15- 30 seconds. Hard carbon steel doesn't roll very easily, but it won't straighten out easily either. In fact it doesn't take much edge flexing for hard carbon to chip. 
 
I'm anxious to learn what you can see with your microscope! I can not detect a rolled edge on my wife's disposable razor with my toy microscope. Hair doesn't seem hard enough to cause the plastic deformation of a rolled edge IMHO. If it could happen, a straight razor should measure dull after shaving, and I haven't seen that. In my experience straight razors dull from oxidation at about the same rate as they do from shaving. Light stropping will bring an edge right back, but I suspect not if the edge were rolled.
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#12
What you say about corrosion makes sense to me Mr. Mark. We don't have a difference of opinion, I just don't know what I'm talking about so I was guessing. I think that sounds better than saying I was showing my ignorance.

I'm really surprised to hear that a straight does not measure duller after shaving. Have you done that experiment?
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#13
"Nicks on my legs? Heavens no. I wax."  Wax?  Ouch Mr. Mark!  The miracle of modern science has created a much better way.  Just imagine, no razors, no waxes or smelly creams!

   
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#14
(02-27-2019, 06:28 PM)grepper Wrote: I'm really surprised to hear that a straight does not measure duller after shaving.  Have you done that experiment?

Yes Sir, Mr. Grepper, I've tested my straight razors, and that was one of the surprising things I learned. 

I would be the first to say that I really don't know much about straights. I haven't studied at all. I haven't been on any razor forums. I don't even have any fancy razors. I bought a few old straight razor blades to see if I could re-handle them and make them work. 

I leave my mustache and goatee, and my beard is soft. Before I used straights a disposable would last... who knows. Probably a dozen shaves at least. I've heard guys say they go through two per week, so mileage varies considerably. 

When I started measuring my straight razor, I found that I wasn't getting it any sharper than my kitchen knives, which was disappointing. Only then did I try to analyze it, and realized that straight razors are nothing fancy. They're just regular old stainless steel, which doesn't support skinny angles, so what could I possibly expect? 

Now take your modern double edge razor blade for instance. The steel is most likely something like Sandvik 12C27 or 13C26, with a RHC 56-58. The best modern sharpening technology will only be BESS 50 Brand New. 24- 48 hours later it might lose 25 points from oxidation, correct?

Even my straight razors are going to be hanging in there with a working sharpness of BESS 75 with minimal stropping. From memory, it really does seem like post shaving sharpness measured virtually the same as pre-shaving, and to me that makes sense because I've never heard of anyone stropping to finish a shave. A blade might measure BESS 100 after a shave and oxidation, but six seconds of stropping will bring it back to BESS 75, time after time.

IMHO, edge stability simply can not be an issue for razors. Hair just isn't enough to distort an edge in my experience. Even my old razor that failed on test media acts/feels just like other blades on my face. I think that's the only way straight razor edges are always measured- by how your face feels afterwords.

I should revisit testing razor blades of all kinds. My memory isn't totally reliable, and I think it would be super beneficial if other guys could do some measuring too. Not just straights, but double edges and disposables too.
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