When coatings of any type are applied to a razor blades, they are not applied to the entire surface of the blade. They are only applied to the apex of each edge. Remember that the blade at it apex is less than 1 micron thick. That is 1 thousandth of a millimeter or 1 millionth of a meter. Even smaller is a nanometer which is 1 thousandth of a micron. A platinum atom has a size of only 0.14 nanometers, so a platinum coating might only be a few nanometers thick.
Optical microscopes are limited in resolution by the wavelength of light, which is 380 (violet) to 700 (red) nanometers. Thus, a white light microscope will be limited in resolution to about 500 nanometers or about 0.5 microns. A 12K Naniwa stone will have grit of approximately 0.8-1 micron in size, so you will be able to see the scratches left behind. If you use a Suehiro Gokumyo 20K or Shapton Glass 30K stone, these are rated at 0.5 micron, so they will produce a mirror finish under an optical microscope as this is approximately the resolution of the microscope. However, I find that my face can distinguish a 0.5 micron edge from one polished with even finer 0.25 and 0.1 micron abrasives, even though the appearance is the same.
A scanning electron microscope (SEM), depending upon its quality has a resolution of 0.5 - 4 nanometers. Thus, depending upon the SEM used, it might not detect a platinum layer if it is only a few molecules thick. To be effective, the edge of the razor blade has to be properly sharpened and polished prior to applying the platinum coating. If the edge is not properly sharpened, the platinum will do no good. You might have heard the old adage that after applying lipstick to a pig, it is still a pig. Some blades are pigs; just because a blade is platinum coated, it does not make it a great blade. That is why I look at the performance of the blade, not whether it is platinum coated.
Optical microscopes are limited in resolution by the wavelength of light, which is 380 (violet) to 700 (red) nanometers. Thus, a white light microscope will be limited in resolution to about 500 nanometers or about 0.5 microns. A 12K Naniwa stone will have grit of approximately 0.8-1 micron in size, so you will be able to see the scratches left behind. If you use a Suehiro Gokumyo 20K or Shapton Glass 30K stone, these are rated at 0.5 micron, so they will produce a mirror finish under an optical microscope as this is approximately the resolution of the microscope. However, I find that my face can distinguish a 0.5 micron edge from one polished with even finer 0.25 and 0.1 micron abrasives, even though the appearance is the same.
A scanning electron microscope (SEM), depending upon its quality has a resolution of 0.5 - 4 nanometers. Thus, depending upon the SEM used, it might not detect a platinum layer if it is only a few molecules thick. To be effective, the edge of the razor blade has to be properly sharpened and polished prior to applying the platinum coating. If the edge is not properly sharpened, the platinum will do no good. You might have heard the old adage that after applying lipstick to a pig, it is still a pig. Some blades are pigs; just because a blade is platinum coated, it does not make it a great blade. That is why I look at the performance of the blade, not whether it is platinum coated.
