Redwood has it down pretty darn close.
I find that the width of the cutting edge is directly proportional to three characteristics
- Thickness at the spine
- Width of the blade
- And... thickness of the blade at the cutting edge
The third characteristic, I think, having the most to do with it. To illustrate, notice that the closer a blade gets to the profile of a wedge shaped blade, the wider the cutting edge winds up being.
In addition, I probably break everyone else's rules here when it comes to honing. I use
considerable pressure at the beginning of each stage of honing on each of the stones I use with and emphasis on the edge rather than the spine. I only lighten up on the pressure with the last 5 -10 strokes on each one of them. ( I normally use only 3 stones )
This process creates an opportunity to address the very edge of the cutting bevel when it is
time to strop. To put it more simply, the back edge of the bevel doesn't have to follow the plane of the front end of it to have great cutting ability.
The extra amount removed from the back of the bevel on a straight razor edge would only be recognizable under some pretty good magnification. But it is often enough to get a very good cutting edge, especially on some of the lesser quality steels. This means that only the very edge of the blade is addressed... not necessarily the entire cutting bevel. ( There... my secret is out :rolleyes: )
The width of the bevel, however, is not an indication on how well the razor will shave. I have some with a 32nd edge that will shave the same as one that is near an 8th. The steel is also a big factor.
This is true on a lot of razors, but not so much with the full hollow grinds on wider blades. Looking at the cross section of one of these will reveal that there looks to be up to a quarter inch of parallel blade thickness before the upward sweep of the grind starts making it thicker. This would mean that you would have a narrower cutting bevel until you honed to that upward sweep as Redwood correctly points out.
If anyone wonders, I sharpen a razor with this progression
- 1,000 grit (only if the blade is really dull)
- 4,000 grit Norton
- 8,000 grit Norton
- .5 green pasted leather honing bed (Hand American)
- plain smooth leather on a honing bed (Hand American)
- touch up on one of Tony's strops