Bottom line: Sure, you can sharpen a safety-razor blade. But it’ll no longer shave. A modern safety razor only works when the blade edge is in exactly the right place. If you remove even a tiny amount of metal from that razor edge, the blade edge will be recessed too far into the razor. It will no longer cut hair well, no matter how sharp it is.
Recap
I started shaving with a safety razor in October 2012. (I just looked up the purchase date on Amazon). At that time, I bought a couple of “blade samplers” then settled on a 100-count box of Personna blades.
A little over a decade later, and it’s getting close to the time to buy some more blades. So I started looking into the market for razor blades, and, by reference, for ways to extend the life of razor blades and disposable razors.
I’ve learned a lot.
Surely the most important thing I learned is that using shaving cream (rather than bar soap) radically extends the life of razor blades. I no longer question people who report being able to use a single high-end disposable cartridge for an extended period of time. Combine a high-fat shaving cream, quality stainless steel, and multiple blades in a cartridge, and it’s entirely plausible that some individuals can routinely use a single shaving cartridge for a month or more.
Arguably the next most important thing I’ve learned is that the level of “innovation” in disposable razor cartridges is, in fact, just as absurd as it looks. For example, Dorco recently produced a seven-blade shaving cartridge. The increasing complexity and cost of shaving cartridges isn’t driven by a need to protect your face. It’s driven by a need to protect profits via patents. And since patents are only good for 20 years, manufacturers must come up with something (anything) new-and-different, so that they can compete in the economic “game of razors-and-blades”.
By contrast, the market for old-school double-edged razor blades is straight-up honestly competitive. Every blade fits every razor, so there’s no way to lock you into a specific product. Dozens of manufacturers compete for your dollars. And as a result, at ten cents a blade, you have your pick of good options. As a result, razor blades are almost unbelievable cheap, compared to what they cost at the dawn of the disposable blade.
The third thing I’ve learned is that a lot of what passes for wisdom in the “wet shaving” world is folklore. Some of it’s true, some of it’s nonsense. Everybody repeats it. Nobody bothers to test it. Except me, and the occasional kindred soul.
In particular, stainless steel razor blades have been sold in the U.S. since before WWII. (And prior to that, non-rusting chromium steel blades were sold). These days, you are hard-pressed to buy blades that aren’t made out of stainless. Unlike old-style carbon steel blades, stainless doesn’t rust, so there’s no need to dry them off after use. That should have been common knowledge since 1940, when the Sears catalog just flat-out said that a benefit of stainless blades is that you don’t need to wipe them off. I proved that drying stainless blades does nothing, via experiment, earlier in this series of posts. And yet, more-or-less every wet shaving site or blog you visit will tell you that you must carefully dry off your blades after use, otherwise it shortens the life of the blade. Which, to be perfectly clear, is wrong for the 99% of modern blades that are made out of stainless steel. And almost certainly is a holdover from the pre-1960s era when carbon-steel blades were still common.
Edit: Nope. See Post #1699. I continued testing, and determined that you do need to dry your stainless-steel blades. But the issue isn’t rust/corrosion (for stainless-steel blades), it’s water spots. It’s due to calcium carbonate deposits from hard water. A typical “water spot” is an order-of-magnitude thicker than the edge of a razor blade, and if you let water spots form on your blade, you end up with a dull blade. If you live in an area with hard water, you do in fact need to dry off your blade. Even your stainless-steel blade.
So, before I actually get around to stropping some blades, I want to ask and answer a series of questions. These may seem obvious to you, but not to me. If you just want to get to my first attempt at literally sharpening a stainless razor blade, skip down — the title of that section is in red
Definitions: Sharpening versus honing versus stropping.
I am not a knife fanatic, so let me offer you my amateur understanding of the distinction between sharpening, honing, and stropping. It boils down to how much material you’re trying to remove. Sharpening typically uses a relatively coarse abrasive and can remove considerable amounts of metal in order to form an edge. Honing uses much finer abrasives, removes little metal, and is more of a way to polish up an already-formed sharp edge. Stropping ideally removes no metal, and either uses no abrasives or very fine abrasives to finish the job of polishing the razor edge of the blade.
The name of the process corresponds to the edge you’re trying to achieve, and where you are in getting to that edge. You sharpen a lawn mower blade. If you care, you might hone an ax after you sharpen it, to get the longest life before re-sharpening is required. If a straight razor is in sad shape, you’d sharpen, hone, and strop it to restore the razor edge.
In the past, when the only option for blade sharpening was scraping a blade across flat stones of various sorts, that could sort-of be correlated with the motions used. You typically sharpen an edge by moving it across the stone in the direction of cutting. You hone an edge by moving it with approximately circular strokes and very light pressure. You strop an edge by moving it backwards — opposite the direction of cutting — over the strop.
So, can I strop a stainless-steel razor blade?
The last thing I need to do, to finish this deep dive into understanding wet shaving, is to learn how to strop a razor blade. In particular, how to strop a stainless-steel razor blade. Correctly. So that it actually sharpens the blade.
Well, yes, I can, in fact, strop a stainless-steel razor blade. I already did that, earlier in this series (Post #1673). Put a stainless blade in your razor, run it backward (opposite the direction of shaving) over a piece of leather, a few times, keeping a fairly steady pressure on the razor. And you’ve just stropped the blade. Flip and repeat.
I can do it, but does it do any good? The results of my first attempt were mediocre. Stropping a blade that way definitely brightened the razor edge, and seemed to remove a lot of irregularities. But it didn’t seem to sharpen that stainless blade, and it didn’t make seem to make it shave any better.
Here’s the big if: I’m not sure it can be done effectively. Or, at least, not by the average user. In my review of the history of the safety-razor market, I noted that the rise of stainless steel blades coincided with the decline in re-sharpening blades via stropping. Early on, it was assumed that the disposable-blade user would strop those blades to maintain a keen edge. Numerous and varied devices were sold to accomplish that task. But those were, by and large, carbon-steel blades, which aren’t as hard as stainless. The practice of stropping razor blades peaked in the 1930s. And as blades got cheaper, and stainless steel took over the market, the practice of routinely stropping razor blades disappeared.
Near as I can tell, nobody offers any device currently for stropping an individual razor blade. There are a handful of devices for stropping shaving cartridges, but I would describe them as “fringe” devices. (Here’s a couple of examples on Amazon (reference, reference)). They say “razor blade” when they actually mean “razor cartridge”. And among the reasons I think of them as “fringe” devices is that their description of what stropping does (cleans, removes oxidation) is a poor match for how blade experts describe the effects of stropping (straightening, re-forming, and polishing the razor edge.)
I am absolutely sure you can strop a stainless-steel straight razor. Experts do that all the time. So there’s nothing about the metal, per se, that prevents stropping. (Although the expert consensus is that a plain-leather strop is inadequate and that abrasive “compound” should be used when stropping stainless).
What I’m not sure is whether I can strop (or hone) an itty-bitty flexible stainless steel razor blade. In some fashion that’s convenient enough that I’d be willing to do it in a routine basis. So the problem here isn’t really one of the science. It’s really about the engineering.
Question 1: Why do they say that you can’t sharpen a double-edged razor blade?
Recall the difference between sharpen, hone, and strop, as defined above.
Even though I am not a knife fanatic, I know that “you can’t sharpen a double-edged razor blade” has to be bullshit. You can sharpen any type of hard metal. So of course you can sharpen a razor blade. I could, if I chose to, pull a thoroughly dull razor blade through my kitchen knife sharpener. And I bet it would come out sharper.
And yet, you will see this repeated as an absolutely unquestionable fact. Everybody knows you can’t sharpen a razor blade. It took me two weeks of playing with razors and blades before it finally dawned on me what they actually mean. Of course you can sharpen a razor blade. But in theory, sharpening a razor blade makes it useless.
Why? Sharpening it — removing enough material to form a new edge — would make it slightly smaller. (And, likely, non-uniform in width.) And a slightly smaller blade won’t work, no matter how sharp it is.
This is the end of my razor, under a microscope. It is manufactured so that the razor blade, when clamped into a curved shape, aligns perfectly with the upper and lower edges of the razor. That’s what puts the “safety” in this type of safety razor. (Separately, the blade also arrives at a precisely-determined angle). I have no way to measure how far the edge of the blade sticks out, but by eye, it’s in tenth-of-a-millimeter territory.
Bottom line: Sure I can sharpen that. And if I manage to scrape 0.1 mm off the edge, the blade will cease to function. Which, given how thin the metal is, and how ham-handed I am with a sharpening stone, is pretty much a given. So, no. In all likelihood, I can’t sharpen a razor blade and continue to use it for shaving.
As a byproduct, I now understand that there’s an ultimate, impassable limit on razor blade re-use. You will eventually wear them down far enough that they will cease to function. They won’t stick out of the razor far enough to cut your hair. No matter what miracle-of-restoration you manage to use, you can’t re-use one of these forever.
Test 1: Run a stainless-steel razor blade through a common kitchen knife sharpener.
Might as well start the practical portion of this by running a used blade through a kitchen knife sharpener. It’s the least-effort approach. The questions are, does that sharpen the blade, and is the blade unusable afterwards.
Now, to be clear, this is not a smart thing to do. If nothing else, the sharpener will be set at too wide an angle, because it’s designed for the edged of knives, not the edges of razors. But let’s proceed and see what happens.
In this case, I’m starting with the ceramic (fine) portion of this $4 knife sharpener. (Which, I will add, works just fine for keeping my stainless-steel kitchen knives sharp.) The ceramic is marked as “sharpening”, but there’s some chance that it merely acts as a hone. I can’t find a definitive answer on that.
Source: Amazon
I marked a badly chipped section of the blade edge, attached a couple of magnets to the blade to form a little handle, then ran that through the ceramic (fine) side. Twenty-four fairly heavy-handed passes through the ceramic (fine) sharpener, and while that chip might be a little more rounded, it’s just about as deep as when I started. That blade edge is so rough that I can actually feel the divots as I run it through the sharpener.
OK, let me try 12 heavy-handed passes through the coarse (carbide) side. For perspective, that’s vastly more passes than I use to dress up even a dull kitchen stainless-steel knife. Normally, I don’t even need to touch the coarse side of the sharpener. At the extreme, I might use five passes coarse and fine to dress the edge of a knife before (say) carving meat.
That finally reduces the nick to the point where I can’t feel it when sharpening. But note that what I’ve done is more-or-less remove the entire second facet of the blade edge. The nick is in the same place. The blade is now ever-so-slightly narrower.
That said, I just tried shaving with it, and I have not narrowed it so much that it doesn’t shave at all. It will still shave, a bit. But it does exactly what you would expect. By moving that edge back, it now leaves stubble. That’s rather subjective, comparing one side of my face shaved with the sharpened edge, and one side shaved with the other edge of the same blade. It’s a very worn blade, and neither edge gives a good shave. But if I had to call it, yep, removing that minuscule amount of steel from the edge makes the blade forever unusable for getting a close shave.
So, I can sharpen it. I did sharpen it. It just won’t shave worth a damn after I did that. No matter how sharp it is. Because it’s now too narrow.
If nothing else, I’ve learned that stainless steel razor blades seem to be extremely hard. For sure, I don’t have to worry about accidentally sharpening them to the point where they are too narrow to function. I really had to work at it do do that.
And I think I’ve confirmed that it’s useless to try to sharpen a razor blade. In the technical sense of removing a significant amount of material in order to produce a more uniform blade edge. Narrowing that razor blade by an amount that is not even visible to the naked eye was enough to render it forever worthless for use in a safety razor.
Finally, I’ll note that because I’m using a kitchen knife sharpener, I’m not sharpening the entire surface of the bevel. The bevel of a razor blade is cut to a much narrower angle than the bevel of a typical kitchen knife. Basically, I’m just sharpening the very tip of the razor edge. So it’s not a huge surprise that this did little more than erode the edge. The interesting part is how little it takes to render the blade useless.
Addendum: Are all stainless razor blades sharpened the same way initially?
Oddly enough, the answer is no. Manufactures put a variety of different edges on their stainless steel razor blades.
The blades that I’ve been putting under a microscope so far — Personnna — were clearly ground at two different angles to form the razor edge. It’s what I’ve termed a “faceted” edge. That seems like a lot of effort for a 10-cent disposable item. But it is what it is.
I’m pretty sure I’m going to erase that if I strop that blade enough. Does that matter? I wonder whether that’s standard practice in the industry?
Below you can see that there is no one industry standard for the final sharpening of a stainless-steel razor blade. You’ve got everything from a simple flat edge, to a faceted (two-angle) edge, to a hollow-ground edge.
I looked at the edges from a random collection of blade brands that I happened to have on hand. Here’s what I think the edge grinding is, based on looking at them under a crude microscope.
- Faceted (two-angle edge): Personna, Voshkod, Shark (I think) Note the clear, distinct line adjacent to the extreme edge of the blade.
- Flat-ground: Astra, Gillette, Feather. No line.
- Hollow-ground: Tiger. You can’t see this in the still photo, but by moving the light source, it was clear that the edge was hollow-ground.
The extra effort in grinding the edge seems to have nothing to do with the quality of the blade. Of these, Feather is almost certainly recognized as the highest-end blade offered, and Feather has a simple flat-ground edge.
In any case, as I proceed, I’m not going to worry about destroying the faceted edge of the blade by stropping. Plenty of razor blades cut just fine with a flat, single-cut edge.
Conclusion
- Stainless steel razor blades appear to be made of extremely hard metal. It took a lot more passes to make a dent in a razor blade than it does to sharpen my stainless steel kitchen knives. (Alternatively, some say that stainless is not hard, but has extremely good wear resistance. I don’t much care what the technically correct explanation is. Either way, it’s a lot harder to sharpen stainless than it is to sharpen carbon steel.)
- Removing even tiny amounts of metal from the edge ruins the blade.
- Manufacturers grind those final edges in all sorts of ways: straight, facet, hollow-ground.
At the end of the day, the key practical question is whether the decline in the practice of stropping razor blades was driven by economics or technology? Did people stop doing that because blades got cheap? Or did people stop doing that because blades started to be made out of much harder material, as the market switched from carbon steel to stainless steel.
At this point, I think I’m leaning toward technology. As of right now, given how hard those blades appear to be, and given that stropping stainless straight razors requires abrasives, it sure looks like it’s going to be difficult or impossible to strop a dull stainless razor blade back to sharpness using any sort of common materials.
Basically, the tricks that might have worked on your grandfather’s carbon-steel blades just ain’t gonna cut it for stainless. And I’m not at all sure what will. I’ll give it a try in my next post.
