Question about sharpness

[Businessness]

I've been lured out of lurking by a question that I could not find the answer to from a search

So we all know how sharp a straight razors edge is by the honing stones progressively used and what grit those stones are. On that same scale where do disposable blades come in? I presume since I've read that disposable blades will always be sharper than honed blades it would be 12,000+?

 

[santamariasteve]

I don't understand the 12,000+.

The sharpness of disposable blades varies by the manufacturer, and also by various experieces of the shavers.

 

[cooltide]

12,000= sharpening stone i guess

 

[seattleshaver]

The question can't really be answered because it's not a matter of a double edge blade being honed to a finer extent than a straight. It's able to be sharper because the edge is thinner than a straight can be.

 

[JBLA]

The number is the grit of the sharpening stone, and doesn't really dictate how sharp the blade is.

Disposable razor blades are sharper than straight razor blades (and most scalpels for that matter).

 

[deruitem]

The number is the grit of the sharpening stone, and doesn't really dictate how sharp the blade is.

Disposable razor blades are sharper than straight razor blades (and most scalpels for that matter).

You can sharpen a blade to as smooth of a stone as you want and still have a dull blade if you don't do it right. Many things can change the "sharpness" like the angle that is used etc. Sharpness it all amount geometry

 

[Businessness]

So does that mean there is no objective way of comparing the sharpness of a DE blade with a honed straight razor?

 

[mblakele]

So does that mean there is no objective way of comparing the sharpness of a DE blade with a honed straight razor?

You could compare the tip radius of the ultimate edges, using an electron microscope. But I am not sure it would be very useful: purely geometrical sharpness is not everything, and may not correlate very well with good shaves.

Most blade manufacturers measure force to cut (FTC), the force required to push a blade into a test material - usually wool felt. They measure FTC over many cuts, to test durability. A really sharp edge is not much good for shaving if it only lasts one stroke. Unfortunately blade makers do not release their test data, and the numbers from one test rig probably are not comparable with another test rig anyhow.

 

[Businessness]

You could compare the tip radius of the ultimate edges, using an electron microscope. But I am not sure it would be very useful: purely geometrical sharpness is not everything, and may not correlate very well with good shaves.

Most blade manufacturers measure force to cut (FTC), the force required to push a blade into a test material - usually wool felt. They measure FTC over many cuts, to test durability. A really sharp edge is not much good for shaving if it only lasts one stroke. Unfortunately blade makers do not release their test data, and the numbers from one test rig probably are not comparable with another test rig anyhow.

Thats the kind of info I'm looking for, thanks!

 

[TimTheEnchanter]

Sorry to bump an old thread but i have been thinking about this lately, has anyone reviewed razor blades from an objective perspective (i.e. Just the non ymmv aspects)?

when i got into bbq and was looking for lump charcoals i found this place: http://www.nakedwhiz.com/lumpindexpage.htm?bag. It would be interesting if there were something similar for de blades that measured the verifiable aspects of each blade (much like was mentioned about the internal sharpness tests).