Bart
Well-Known Member
Gentlemen,
It has come to my attention that few people understand about warp, and how it affect the sharpening of a razor. First allow me to tell something that may come as a surprise. Straight razors are rarely straight. This is due to the hardening process of the the razor blanks. The blade is heated to high temperature and than quenched in a bath, to quickly cool it, which "freezes" the steel structure without giving it time to relax. The result is hard and resilient, yet brittle steel. Too brittle, hence during the next step the blade is tempered, in order to release stresses and regain some ductility. Needless to say, that all stresses occurring and being relieved during this part of the production process sometimes alters the shape of the blade a bit. The result is a blade slightly out of true. This is further corrected during the grinding process, but even so, no straight razor blade is mathematically straight. This was one of the reasons why razors were produced with a smiling curve at the edge, as I'm about to illustrate. But, as smiling edges take some additional skills to sharpen them well, and perhaps because straight edges might be easier to produce, a lot of modern razors come with a straight edge.
Time to show a drawing:
[img=800]http://www.coticule.be/tl_files/barts_pics/blade&edge_conditions.jpg[/img]
At the top left, we see a razor without any significant warp, produced with a straight (non-smiling) edge. This is what many people consider to be a perfect razor. But is says nothing about the edge it is capable to take, because, that is all in the steel. It is also the kind of razor that invites inexperienced honers to push a razor up and down across the hone. That should work, in this case, although years of honing will probably introduce unevenly honed spine and edge parts, because whatever unbalance in pressure and honing stroke is repeated over and over again at the same spot.
Next, we see two drawings of a warped razor. It's the same warp both times, the razor turned over. You can see how at one side, only the middle part of the edge will touch the hone and at the other side the heel and tip will make contact. Obviously, I have exaggerated the drawing for clarity. This razor requires the X-stroke on one side and the rolling X-stroke at the other. By shifting the points of contact at the side of the hone, all of the edge will at some point during the stroke touch the hone. In a manner of speaking, the hone follows the curve in the blade. In no way, this must be considered a defect, because: 1. a lot of modern razors would need to be considered defect. And 2: once sharpened these razors shave perfect, because, as mentioned, the quality of the edge capable is all about the steel.
Only in rare cases a blade can be so severely warped that it becomes very difficult to sharpen in correctly. I have only encountered such a razor once, and with a very narrow hone and a good X-stroke I managed to get it sharpened after all. And it turned out to be an exceptionally smooth shaver. So smooth that I honed with the narrow hone for weeks, because I thought the magic was in the hone.
On the second row, at the left, we see a razor without any significant warp again. This time one with a smiling curve at the edge. When put on the hone, only the middle part of the edge makes proper contact. Please pay notice how much this situation resembles that of the top right (straight edge, warped blade). Also this blade can't be sharpened without a rolling X-stroke.
The final images both show the warped condition of a razor with smiling edge. On one side of the blade, the smiling edge overrules the "frown" of the warp. This is the reason why no one ever notices warp in a smiling razors. One needs to adopt a rolling X-stroke anyway, so the warp goes unnoticed. At the opposite side of the blade, the warp amplifies the smile, which just calls for a bit more outspoken roll in the stroke.
Thank you for your attention.
Kind regards,
Bart.
It has come to my attention that few people understand about warp, and how it affect the sharpening of a razor. First allow me to tell something that may come as a surprise. Straight razors are rarely straight. This is due to the hardening process of the the razor blanks. The blade is heated to high temperature and than quenched in a bath, to quickly cool it, which "freezes" the steel structure without giving it time to relax. The result is hard and resilient, yet brittle steel. Too brittle, hence during the next step the blade is tempered, in order to release stresses and regain some ductility. Needless to say, that all stresses occurring and being relieved during this part of the production process sometimes alters the shape of the blade a bit. The result is a blade slightly out of true. This is further corrected during the grinding process, but even so, no straight razor blade is mathematically straight. This was one of the reasons why razors were produced with a smiling curve at the edge, as I'm about to illustrate. But, as smiling edges take some additional skills to sharpen them well, and perhaps because straight edges might be easier to produce, a lot of modern razors come with a straight edge.
Time to show a drawing:
[img=800]http://www.coticule.be/tl_files/barts_pics/blade&edge_conditions.jpg[/img]
At the top left, we see a razor without any significant warp, produced with a straight (non-smiling) edge. This is what many people consider to be a perfect razor. But is says nothing about the edge it is capable to take, because, that is all in the steel. It is also the kind of razor that invites inexperienced honers to push a razor up and down across the hone. That should work, in this case, although years of honing will probably introduce unevenly honed spine and edge parts, because whatever unbalance in pressure and honing stroke is repeated over and over again at the same spot.
Next, we see two drawings of a warped razor. It's the same warp both times, the razor turned over. You can see how at one side, only the middle part of the edge will touch the hone and at the other side the heel and tip will make contact. Obviously, I have exaggerated the drawing for clarity. This razor requires the X-stroke on one side and the rolling X-stroke at the other. By shifting the points of contact at the side of the hone, all of the edge will at some point during the stroke touch the hone. In a manner of speaking, the hone follows the curve in the blade. In no way, this must be considered a defect, because: 1. a lot of modern razors would need to be considered defect. And 2: once sharpened these razors shave perfect, because, as mentioned, the quality of the edge capable is all about the steel.
Only in rare cases a blade can be so severely warped that it becomes very difficult to sharpen in correctly. I have only encountered such a razor once, and with a very narrow hone and a good X-stroke I managed to get it sharpened after all. And it turned out to be an exceptionally smooth shaver. So smooth that I honed with the narrow hone for weeks, because I thought the magic was in the hone.
On the second row, at the left, we see a razor without any significant warp again. This time one with a smiling curve at the edge. When put on the hone, only the middle part of the edge makes proper contact. Please pay notice how much this situation resembles that of the top right (straight edge, warped blade). Also this blade can't be sharpened without a rolling X-stroke.
The final images both show the warped condition of a razor with smiling edge. On one side of the blade, the smiling edge overrules the "frown" of the warp. This is the reason why no one ever notices warp in a smiling razors. One needs to adopt a rolling X-stroke anyway, so the warp goes unnoticed. At the opposite side of the blade, the warp amplifies the smile, which just calls for a bit more outspoken roll in the stroke.
Thank you for your attention.
Kind regards,
Bart.