wdwrx said:
The Strike-Off is not necessarily to remove a “wire-edge”… it’s to remove a small amount of steel from the edge because it is too thin and week to form a bevel (filmy-edge).
To understand the “filmy-edge” you may have to think of how a razor is manufactured, and the condition the razor at the time they are honing it (yes, they sharpen all razors at the factory before it goes to market).
The razor has just been ground and polished on wheels. It is the wheels that create the concave on each side of the blade. The concaves meet at the very edge, and the result is thin “filmy” steel at the edge (like aluminum foil)… there is NO bevel. A proper cutting edge needs a bevel, however they couldn’t form a bevel on such a thin edge because it is too week and would flex away from the hone. So they strike-off the very thin part of the edge on a course stone, so the edge gets just a little thicker (and stronger), then they commence to form the bevel on the razor hone (sharpen the razor).
The wire-edge is similar to the filmy-edge, but the cause is different. The wire-edge is formed when the bevels meet, but you continue honing (over-honing) and thus forming another film at the edge. In this case, it is indeed a wire because, though the steel is still attached to the bevel, is not part of the bevel (the filmy-edge mentioned previously, was part of the concave).
But as mentioned in the chapter “setting razors”, the wire is more likely to occur if the steel is too soft, the edge is thin, but week, and will flex away from the hone. On the other hand, if steel that is too hard, it will instead fracture and brake off at the very edge and become notched (because it is brittle), so, hard razors will never form a wire by over-honing.
The best steel is not too hard… not too soft… “Today” it is indeed difficult for the average shaver to find a razor the middle.
The TPT is controversial… Folks will gladly accept the TPT when setting the bevel on a course stone… but they often go into “meltdown” if you mention the TPT during the polishing stages or when the blade is “shave ready”.
But my philosophy is this… if at the polishing stage, an edge cannot survive a trip through the thumbnail, then the resulting shave will be lacking, even if the TNT was never used. I have proven this to myself so many times that I am beginning to think it's time to bust this "myth".