What do people mean when they say that conventional butcher's steels don’t actually sharpen your knife.  According to the Merriam-Webster on-line dictionary, sharpen means to "make sharp or sharper."  It seems to me that is why I use a steel, and the effect that it has.

--Art

OK, this is something that really bugs me too.  It all boils down to some subtle semantics.

If you look at the edge of a freshly sharpened knife under a microscope, its cross section will look like the letter V, coming to a fine point.  With use, the edge of the V starts to curl over.  At that point, if you look under the microscope again, what you will see is something like the tail of the letter J, the little curled part at the bottom, where the sharp point of the V used to be.  The curl is the result of use, and abrasion against the cutting surface or other materials.

Depending on which reference you look at, a conventional butcher's steel either removes the curl or straightens it back out.  Some people say it "realigns" the curl, whatever that means.  After using the steel, the knife is sharper than it was before using the steel, but not as keen as a newley sharpened knife.  In any case, the curl eventually breaks off and rather than coming to a point, the edge is blunted.  Imagine a V with a flat or rounded bottom.

Repeated use of the knife and application of the steel eventually makes the knife edge so blunt that in order to sharpen it again metal has to be removed from the two faces of the V to bring them back into a point.  Then it is necessary to use a grinder, whetstone or other device that actually takes away metal.  I use a set of Japanese water stones running from 250 grit to take of the dull edge fast, 1000 grit to sharpen, and then 4000 grit to give a razor sharp mirror finish.

Ceramic steels and ones with diamond dust embedded in their surface actually do remove some metal from the surface, but because they are a fine abrasive, they can't be used easily to re-sharpen a blade that has become too dull.  They are better than a conventional steel at keeping an edge, though.

So:

• A conventional butcher's steel does make a knife sharper, so it sharpens!
• It does not deliberately remove metal from the face of the knife so it doesn't sharpen in the same sense that, say, a whetstone does.
• A ceramic or diamond steel does remove metal from the face, but is not efficient for sharpening an already dull knife.

For the record, I am not a fan of the little pull sharpeners with the handle and a notch to pull the knife through .  I find that while they are convenient, they don't do nearly as good a job as my whetstones and a bit of elbow grease, and they are more aggressive than is needed for times when only a steel is called for.  To me they are a poor middle of the road compromise.