Edit: Nope. See below. Honing a worn stainless-steel blade with a knife steel made the edges look a lot better. But the blade still shaves badly. And I have no idea why.
I think I’ve figured out a possibly-effective way to strop or hone a stainless steel razor blade. Possibly. Use a sharpening steel. The thing pictured at the top of the post.
Don’t use an abrasive (e.g., diamond) steel. Use a common carbon-steel knife sharpening rod. The last post demonstrated that you can’t abrade much off the edge before the blade is ruined for shaving.
Use the “pull” technique. Weirdly enough, half the experts on Youtube pull the blade across the steel. Half push the blade, as if you were cutting into the steel. That suggests to me that this works either way. And pulling a razor blade is going to be a lot easier. Like this technique (Youtube link).
Hold the blade at very shallow angle to the knife steel. Start at one side of the edge, and pull it across and up the steel. Flip and repeat as often as you want, because, based no seemingly expert authority, it’s almost impossible to over-steel a knife edge.
I’m not entirely sure this works, but it’s the best I’ve come up with, and it seems to do something.
For sure, this does nothing for any chips in the blade edge that are large enough to be visible with a microscope. So if a blade edge is badly eroded, honing it in this fashion isn’t going to fix it. But, that’s fair, as honing or stropping isn’t supposed to repair a damaged cutting edge. Those really just clean up the very final finish on an otherwise sound cutting edge.
But, maybe it does something to the very edge of the blade. After vigorous stropping in this fashion, the stropped edge of a razor blade feels sharper when run across the ball of the finger. So much so that I can tell one edge from the other in a blind test.
Unfortunately, I have no other evidence that this is actually doing anything. Whatever is happening at the very knife-edge of the steel is far too small for me to see with my crude microscope. My home-made sharpness tester had too high a variance to tell me much. And, with one blind shave test, I can’t really feel any difference in shaving.
Edit: Finally, after 11 shaves with one Personna blade and Barbasol, I judged the shave to be inadequate. Here’s a contrast of the worn blade and a new blade, after that 11th shave. You can clearly see that the new edge is perfectly straight, but that the worn edge has quite a ragged appearance.
(Parenthetically, you can see what a difference shaving cream makes relative to Dove soap. Unlike my used blades after soap shaving, on this blade there are no huge nicks in the edge, just an uneven razor edge.)
This amount of edge wear is enough to cause me to change to a fresh blade.
I did my best to see whether or not the blade was any narrower, per my prior experiment in sharpening a blade. As far as I tell, it’s not. So I’m not wearing out the blade by making it too small to give a good shave. (If that were true, there would be no point in proceeding, because I can’t restore the blade to its original width.) I’m wearing out the blade by giving it a ragged razor edge.
So, what the heck. I carefully steeled/honed that worn blade. Held the blade in my hand, and gave it about ten strokes across the steel, on each edge, flipping the blade with each stroke.
Below you see two views of the same pair of blades after passing the worn blade over the knife steel. By eye, the worn edge now appears somewhat less ragged. Not perfect, but significantly straighter. Which, I think, is roughly what a knife steel ought to do. Clean up the very tip of the razor edge of the blade.
I still don’t know if this improved the blade enough that it can still used. But I’m going to try shaving with it tomorrow. (Honestly, it’s hard even to be sure that I’m not kidding myself about the steeled edge being straighter.) Shaving is clearly going to be a subjective test, and if I’d thought about it, I’d have steeled just one edge, so I could do a blind shave test of one edge versus the other. But that’s water over the dam at this point.
I’ll re-edit this one more time, after I’ve shaved with the worn-and-carefully-steeled blade.
Final edit: Still doesn’t shave worth a damn. I have no idea why.
The blade remains the correct width. I pulled out a micrometer, and the worn blade is exactly the same edge-to-edge width as a new blade (to within the 0.01 mm resolution of the tool.)
The blade edge looks good. Under magnification (with a cheap USB microscope), the blade edge is nice and straight. I’m hard pressed to tell the used blade from a new blade.
The upshot is that I have no clue why the blade won’t shave. Possibly the blade wear goes on at a scale that I just can’t see with my current level of magnification? I hate to leave it like that, but I can’t see any reason why this blade no longer shaves well. But it doesn’t.
That said, this brings my razor blade deep-dive to closure. The final question was whether or not there was anything you could do to re-sharpen a stainless-steel blade. Edit: My answer is, yeah, maybe. Try using a knife steel. As of this writing, my answer is no. As with stropping on leather, I can use a knife steel to clean up the edge, but I can’t make the blade shave well again.
Finally, I am virtually certain that all the methods you may see on the internet, for stropping a razor blade, are simply folklore. E.g., rub the blade on the inside of a glass, strop it on denim, and so on. These probably date back to the era of carbon-steel blades. I’m pretty sure stainless is just too hard (or wear-resistant) for those to work.
Even a proper leather strop merely shined up and cleaned up my blade edge. It didn’t make it any sharper or better for shaving. Experts say that you need to use abrasives, if you plan to strop stainless on leather. My guess is that this is good advice. But unlike a knife blade, you can’t afford to lose even a smidgen of metal off the edge of a razor blade, or it will no longer function in a safety razor. So I don’t think abrasives are the answer here. But I have to note that I have not actually tried loading up a leather strop with the proper stropping abrasive and having at it.
So, the only other object commonly used for cleaning up the edge of a stainless blade, without abrading it, is a knife steel. Knife steels definitely work on stainless knives. There’s no reason to think they won’t work on stainless razor blades.
And, near as I can tell, yes, steeling a stainless razor blade in this fashion does something. Kinda. I guess?
So with that, I’m calling it a day.
