Thread: Stropping is King

Originally Posted by AFDavis11

Im inclined to not believe that heat is the catalyst.

I agree. You can buff a blade for a long time on a machine before you feel the temperature increase. It's not likely you could do it manually.

2¢ here. Heat stressing of metal occurs simply from the friction of the iron atoms against one another by bending. That has an effect.

X

Originally Posted by mparker762

Or it's possible that unpasted strops are more abrasive than we've been giving them credit for.

I think that's the case with the strop Scott is using. He's not doing enough reps for a clean leather strop to generate the necessary abrasion, but he does have to remove the same material that a .5 micron strop would in 20 reps. He has 400 reps to do it. If he had 4000, maybe a plain leather strop would work.

Originally Posted by joshearl

This morning I tested my razor before stropping. It broke hairs, but didn't cut them cleanly. After 30 laps on the linen, it was back to popping hairs. I'm amazed at how well the linen works; Kees mentioned an abrasive in the linen, and I wouldn't be surprised. I used to think it was just cloth.

About 50 strokes with medium-easing-to-light pressure on the leather put an even finer edge on the razor. Cut cleanly through hanging hairs--wow. I'm on my third shave since the pasted strops and there's no noticeable dropoff in sharpness.

The idea is not to use anything but the linnen and leather of the strop and see if you reach a point where just stropping will not restore the edge.

Originally Posted by xman

2¢ here. Heat stressing of metal occurs simply from the friction of the iron atoms against one another by bending. That has an effect.

True, but it won't elevate tempperature to the point you can sense it without instruments.

You guys don't think he is just realigning the edge with stropping? Or put another way, realigning it better?

Because the science and theory say "it won't work" it doesn't explain why it does. I can't be persueded that stropping doesn't remove enuough material to sharpen an edge and polish at the same time.
Granted it will take longer, but then I'd expect it to. After finish honing with say a 8-12k hone, you could only go to something finer for the finishing steps with a strop. I base this on the leather strop wheels i use on my lathe for sharpening wood turning chisels. After grinding to the correct bevel and sharpness, I then put them across my leather hone mop. This you can see metal being removed all be it, slower. I will concede that heat is produced but this is not what removes metal, it's the abrasive qualities of the leather. I must point out that the speed is 300rpm or lower depending on the weight/mass of the tool being sharpened so that heat is not going to draw the temper too fast to correct.
So my point is that a plain leather strop does sharpen a razor all be it slow and finely. To use pasted strops just speeds up procees like going from 4k to 8k on a hone.

PuFF

Originally Posted by AFDavis11

You guys don't think he is just realigning the edge with stropping? Or put another way, realigning it better?

I do. We're talking about the thinnest steel known to man (feathers and some atomic science weirdness aside). I believe it responds to everything we do with it. If shaving against my puny whiskers puts the edge out of joint, I'm sure stropping can have a profound effect if taken to extremes and perhaps even not that far.

X

Originally Posted by AFDavis11

You guys don't think he is just realigning the edge with stropping? Or put another way, realigning it better?

I'm skeptical. Linen and leather are both abrasive to some degree, linen is probably the more abrasive of the two.

somewhat off-topic but possibly relevant: I've got a few muzzleloaders, and muzzleloading rifles use a lead ball wrapped in cloth and shoved down the barrel. After a few cycles of the cloth-wrapped ball going down and up the barrel the inside of the barrel gets noticeably polished - machining marks are gone, the corners of the lands lose their sharpness, etc. And muzzleloader patches are made of pillow ticking which is a lot softer than linen.

Now rifle barrels aren't as hard as a razor blade, but I can easily believe that an unpasted linen strop is some reasonable percentage as abrasive as a .5 chrome oxide paddle - if it's even 2% as abrasive then giving the razor 80 firm laps on it may be equivalent to as much as 10 light laps on CrOx, which will make a substantial difference in the quality of the edge.

As for why the razor needs light stropping after the firm regimen, the newly-refreshed fin will be left bent over from the hard stropping (this sounds like a tenacious d song) and still needs to be aligned.

One theory I've heard put forward by someone very experienced in metallurgy is that the oxidation and removal of the oxidation is what really causes the "fin regeneration". Fishhooks and files are two steel tools that are acid sharpened. Essentially, they're sharpened by chemically oxidizing the steel. When the oxidation is removed, a fresh layer of steel that is "chemically sharpened" is revealed.

I can neither confirm nor deny this theory, but thought I'd mention it.

As best I can tell, stropping simply polishes and refines the edge by abrasion.