Honing Straight razors
Honing is what makes the difference between an effortless, close, smooth shave, and a painful, tugging, awful shave.
The best way to evaluate the edge that is put on a razor is by actually shaving with it. However, I feel that it is preferable to try and gather as much information as possible prior to putting blade to face. Some tests are somewhat subjective: the "Hanging Hair Test"-how easily the razor will cut an unsupported hair, the "Thumbpad test"- how the edge feels as it is drawn lightly through the fleshy part of your thumbpad...(I have never employed this method..sounds a bit sadomasochistic).
So, my favorite method of evaluating edges?
The microscope!
It is as close to empirical as we can get in the art of honing, but is by no means foolproof. The angle of the razor relative to the objective lens, the lighting angle all can give different looking images. I have found what I feel gives a good, repeatable image, and I try and maintain that setup when evaluating edges.
The best way to evaluate the edge that is put on a razor is by actually shaving with it. However, I feel that it is preferable to try and gather as much information as possible prior to putting blade to face. Some tests are somewhat subjective: the "Hanging Hair Test"-how easily the razor will cut an unsupported hair, the "Thumbpad test"- how the edge feels as it is drawn lightly through the fleshy part of your thumbpad...(I have never employed this method..sounds a bit sadomasochistic).
So, my favorite method of evaluating edges?
The microscope!
It is as close to empirical as we can get in the art of honing, but is by no means foolproof. The angle of the razor relative to the objective lens, the lighting angle all can give different looking images. I have found what I feel gives a good, repeatable image, and I try and maintain that setup when evaluating edges.
With different size monitors, etc it is difficult to say exactly what magnification these images are. I generally refer to them as ~400x. At the right you can see a pair of calipers set to 0.10mm, or 100 microns, and below that is the image taken of that caliper spacing through my microscope setup to give you an idea of the scale the images are taken at.
My preference for honing is to use lapping films over a precision granite surface plate. I find the results to be very consistent, and the lapping films are capable of honing any razor material or hardness without a problem. Even ceramic and Tungsten carbide.
My preference for honing is to use lapping films over a precision granite surface plate. I find the results to be very consistent, and the lapping films are capable of honing any razor material or hardness without a problem. Even ceramic and Tungsten carbide.
Honing progression
Honing involves removing bulk material to enable a sharp V edge to be formed, and then to further refine that edge to smoothness to allow for a comfortable, effortless shave.
At left is a pictorial representation of the edge on a particular razor as it progressed through a honing process. The edge as it came from the factory was quite rough and required a bit of work to get it to come around.
By the time the process was complete, you can see how the finished edge on the straight razor compares to a commercially available DE blade shown in the last picture.
At left is a pictorial representation of the edge on a particular razor as it progressed through a honing process. The edge as it came from the factory was quite rough and required a bit of work to get it to come around.
By the time the process was complete, you can see how the finished edge on the straight razor compares to a commercially available DE blade shown in the last picture.
HHT Hanging Hair Test
While not an absolute measurement, testing a razor's edge by cleaving a hair does give some excellent information as to the cutting ability of the honing. Some edges will cut a hair, but the hair gives a bit of a *pop* while being severed. I like to aim for a silent HHT, where the hair is parted with no resistance, no noise, no tactile response. What the hair looks like after such a cut is shown at the right.