Thread: edge properties, wiki invitation

Hi all,


It may be because I'm (i) a beginner, (ii) not a native english speaker, or (iii) not good at searching online, but it is very hard for me to get a list of all properties or characteristics that an edge can have, and how they interact with or depend on each other.

From my limited experience, it feels like an edge can be evaluated on 3 dependent scales (relevant to the shave):
1) sharpness: from sharp (100%) to dull (0%) ; capacity of cutting or slicing things, in particular facial hair and whiskers.
2) smoothness: from smooth (100%) to harsh (0%) ; capacity of shaving without irritating, burning, or damaging the skin.
3) indulgence: from forgiving (100%) to unforgiving (0%) ; capacity of providing a close, safe, and good shave despite a less-than-perfect shaving technique(s).

My questions are:
- are there other edge properties (relevant to the shave) than these three?
- how do they interact with each other? (i.e. is there any trade off between 1, 2, and 3?)
- is "keenness" a synonym for "sharpness"? If yes, where would "sharp" be on the "keenness" scale, or, conversely, where would "keen" be on the "sharpness" scale?

I think a wiki page dedicated to this vocabulary would be very useful for beginners, in particular when asking questions on the forum or learning to hone. Unfortunately, I'm not knowledgeable enough to start one. That's why I invite anybody who feel like it, to create one following this thread, where each scale definition and interactions would be expanded.


Thank you,
Christophe

Christophe,
I'm by no means an authority on the subject, and a section in the wiki on the subject may be of help, but here's what I'll add for discussion...

Sharpness and Keenness are synonyms. The evaluation of which are completely subjective when you get into the realms of razordom.

Sharpness relates to the establishment of a bevel, the proper geometry of which is incredibly effective at cutting hair. With razors, that geometry relies upon a 15 degree angle give or take a degree (the old tape or not to tape debate). The condition of that bevel is the only objective measure of sharpness.

Smoothness relates to the microscopic topography of the bevel. A sharp bevel can shave hair off of a 1k stone, but it would be painful to shave with. A high grit stone (12k+) smooths the bevel so that it has a more uniform cutting surface and delivers a more comfortable shave. A low grit bevel looks like a serrated knife, under magnification. After a high grit stone, the bevel looks more like a smooth bladed knife.

I think indulgence is a subjective expression of the experience of a shave. A razor for one person might be very forgiving, and for the next guy unforgiving. The only measure of "indulgence" I could think of would be the effects of a round point vs. a square point, a smile vs. a straight blade, wedges vs. hollow grounds, width and length, etc. But even these are highly subjective as each person's face, neck, etc are shaped differently.

FWIW!

Peace,
Jim

It seems to me that numbers 1, 2, and 3 are more telling factors for beginners when applied to their shaving skill than the razors' edges