Contrary to what most people believe, men (and women) who use safety razors need not discard the blades after three or four shaves. I’m not entirely certain that the reason I’ve stated below is accurate, but I can assure you that the technique described works. I’ve been doing it for well over 20 years, and getting four to six weeks of use out of one blade (even before the beard).
The method is simple:
a. always rinse the blade in cold water, while shaving and afterward, not hot or warm;
b. immediately after the final rinse, immerse it in rubbing alcohol for a moment and store it in a dry place with the blade edge upward.
I have been told that the blades do not dull rapidly, but that rinsing in hot water causes the formation of microscopic mineral crystals along the edge, which create a “saw edge” effect and cause the dragging that leads to razor burns and cuts — normally associated with a “dull” blade.
Chemically, it makes sense. Hot water carries dissolved minerals. When it evaporates, it deposits them in crystal form along the fine edge of the blade. Alcohol displaces the mineral-bearing water before it can evaporate, and itself evaporates without leaving any noticeable residue.
I know that this little trick works. I also know that a few years ago a company came out with a “shaving system” that incorporated the same idea. It worked, too. After a few months, it disappeared from the market. Draw your own conclusions about that.