Ok, well first of all, honing a razor is not like sharpening a knife in that the bevel geometry is built into the razor. A typical American knife has a bevel angle of approx. 20 degrees, and when sharpened, the knife must be held with the spine off the stone or hone high enough to generate this angle. A straight razor is made differently; the width of the blade and the thickness of the spine combine to generate the correct bevel angle at the edge. To hone a razor, it is simply laid flat on the hone and pushed along. That is about the last thing that is simple but at least that one is a freebie. Please excuse this terrible photo of a razor's end with approximate lines drawn in where the razor will lay flat on a hone:
The first hone I use, also called a bevel setter because it is coarse enough to actually remove significant metal and shape the bevel, is a DMT diamond hone, 1200 grit. A very fast cutter. I use it wet but it that is not nessasary. Please note the filthy "honing towel" to the right of the hone- that is required apparently :-) The hone is made of steel, diamond coated and is 3/8" X 3" X 8" long. This is not how I hold the razor to actually hone it but just wanted to show the basic relationship between razor and hone:
Once the edge is an true edge (i.e., bevels meeting in a true 'V' and having a true edge), the rest of the process is really just refining that edge. I use lapping film; the color indicates grit rating of the abrasive. Unlike what we are used to regarding normal sandpaper which measures the grit size by how many will fit into one inch (each grain of 100 grit sandpaper is 1/100th of an inch), most fine synthetic abrasives are rated in microns which measures the size of each piece of abrasive; one micron is one millionth of a meter, or about 39.4 millionths of an inch. The pink film is 3 micron (about 7,000 grit), the green is 1 micron (14,000 grit) and the white is 0.3 micron (about 100,000 grit.
I use a piece of glass as a lapping plate, which is 1/4" X 4" X 14". Water is used to hold the film onto the plate; both must be extremely clean because any debris, even a particle of dust, will chip the razor's edge (and it feels like a boulder when the razor 'skips' over it). A squeegee is used to tightly press the film in place and remove any air bubbles, again those would be lumps to the razor.
Some water, a razor and we're ready to have fun....
After a bunch of laps (one stroke up, razor flipped over and a stroke back) the film is changed to the next grit. A microscope or jeweler's loupe is used to see the edge being refined; when all the previous abrasive's scratch patterns are gone, the razor is finished on that particular grit.
In the olden' days, barbers used to hone to about 8,000 grit, strop the living pants out of a razor and use it. Today that is considered too coarse by most to shave with. 1 micron (14,000 grit) film, followed by a lot of stropping on linen and then leather (maybe 50 laps each) is adequate for a decent shave but finer is better. I like edges as sharp as they can be made and the way I get there is abrasive slurries spread on hard balsa paddles. The old standby in the lapping world has always been chromium oxide, a moderately fast cutter that leaves a very nice edge. It is usually found in 0.5 micron size, or about 60,000 grit rating. By the way, the biggest use for the compound chrome oxide is as a pigment for paints and the printing industry. I also use diamond abrasives carried and applied in ion free water. The two grits I use are 0.5 micron and 0.25 micron. Finally, my very finest abrasive slurry is 0.1 micron, about 200,000 grit, and is CBN, a man made material unlike diamond (CBN= Cubic Boron Nitride, nearly as hard as diamond and a very fast cutter).
The abrasives are applied to balsa and the razor is honed on the but backwards- the blade is moved spine- leading, unlike traditional honing which is always edge- leading (that helps prevent a foil edge from forming but the synthetics are so fine and fast they don't tend to create foil edges).
Very few laps needed or wanted at this point. Literally 5 laps on 0.5 diamond, followed by no more than 15 laps, and those are much more vertical than horizontal (dragging the razor from heel to toe more then going down the length of the paddle).
A new commercial razor blade will have an edge somewhere around 0.25 microns wide, a touch less if it is something like a Japanese made Feather blade. A very well honed and stropped razor will have a cutting edge around 0.1 micron wide, maybe a touch thinner, and that is a little less than 4 millionths of an inch.
You guys do understand this is a hobby and I am not doing all of this to get a shave, right?
Now if anyone is really interested, this is a link to another shaving hobby gentleman who happens to have access to a Scanning Electron Microscope (S.E.M.). Razor's edges cannot be seen optically but throw a stream of electrons at one, watch where they bounce and viola!
http://www.flickr.com/photos/nanofab/page3/Brian (busily growing facial hair so it can meet its just reward)
Shoot man, post away.
