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Straight razor use, honing and restoration

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How bad is pitting really? (self.straight_razors)

submitted 1 year ago by HomeAwayFromHone to c/straight_razors

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So, typically, I try to hone through any pitting to get a clean edge. I might tolerate some on the bevel, but not right near the edge where the stresses of shaving and stropping might cause it to collapse and break that nice clean line.

However...

I have this one razor. I used it today. I quite like it: it has very little wear and was well ground so it has a very thin bevel. It shaves well and it holds an edge. Indeed, it's one of the few edges I've put a dozen shaves on. But I have a confession: I left a tiny pit at the edge. Because there was probably going to be another and another and... well, usually I'd just take some metal off until we were in reasonable steel. I didn't want to this time, so I left all this (which you can only see at all on one side):

...and while I had a mostly clean edge, it did have a small pit at the edge. But nothing major, it's not a serrated knife or anything. So I went with it to see what happened. Every shave I made a point to see if the heel was giving me more irritation than elsewhere on the blade or anything like that and ...nah. It's fine.

Which reminded me of this post at Science of Sharp where you can see, based on the scale, how very much bigger a hair is than a razor edge. And I think my skin is at least as thick as a hair or I'd be bleeding way more often. A quick search confirms even the thinnest skin (eyelids apparently) has something like 50 microns of epidermis.

So maybe I shouldn't be so surprised that I can't notice a difference from some tiny pit on the edge? Maybe I should more often err on the side of leaving steel on a nice blade even if it's not so great?

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[–] HomeAwayFromHone 3 points 1 year ago

To be fair, when I decided to keep the pit I did take steps to mitigate it: I was sure to use a coticule with slurry as prefinisher and do a generous number of laps and finish on a JNAT with yet more slurry involved with the sense that the slurry would help round out any rough edges. And the razor was treated with Evap-o-rust in an ultrasonic as the pits might otherwise be hiding some active rust. With the same concern in mind I do also make even more careful a point than usual to strop this on linen right after I shave to ensure it's fully dry.

[–] gcgallant 3 points 1 year ago (1 children)

I've followed Science of Sharp for many years. Excellent information there.

I'm thinking that you're saved by the fact that the pitting is at the heel, there's a small pit (singular), and you probably don't rely that area too much when shaving.

I have found that small variations that form a toothy edge can be felt, and can contribute to a feeling of edge harshness. Generally you need a toothy section that extends along a sizeable section of the blade, though. In my experience, if the blade is toothy with unevenness above ~5 microns I can feel it. A single anomaly or tiny area that's toothy, though, I can't detect.

When I see pitting on a razor that I'm interested in buying I just shy away because even though the oxidation may have been halted, the steel might be compromised. My first consideration is, "do I want to spend the time to reprofile this razor?" (where the real work might be in adjusting the spine).

[–] HomeAwayFromHone 2 points 1 year ago (1 children)

you probably don’t rely that area too much when shaving

I use it a fair bit. I did less so initially but have come to appreciate a certain firmness of grip and control at the heel. After all, it's closest to where I'm holding the thing. And with this razor I quite intentionally make extra use of it in places where I wouldn't usually as I'm trying to convince myself it's fine as-is and I don't need to grind off the heel.

Generally you need a toothy section that extends along a sizable section of the blade, though.

A single anomaly or tiny area that’s toothy, though, I can’t detect.

That's what I'm starting to learn here. Science of Sharp is helpful in that it shows how much we can't see with anything short of an electron microscope. I imagine if there is a fair bit all over the edge that's visible, there's even more that's not. Whereas if it's perhaps just this one pit (which must be cavernous at that scale) so long as it it's not bending outwards or otherwise jagged perhaps it really doesn't affect things all that much. Seems it's like anything, the only real test we have is to shave with it. Tricky though as irritation can be rather subtle.

And so thanks for the affirmation, I was second guessing myself a bit there...

the steel might be compromised

Yes, that is a real fear---it's dispiriting to finish a razor carefully only to find the steel can't hold an edge at that angle and then to have to take it back to be made more obtuse (if still in a reasonable range) or ground down a bit further (but not too far!) in order to get to good metal. Over and over again. I like honing but somehow it takes the joy out of it a bit when it's the 3rd time and still no usable edge (and of course I'm aiming for better than just usable).

(where the real work might be in adjusting the spine)

I used to believe it was worth aiming for 16 degrees but then I wound up with a Koraat that clocks in at 20.5. In trying to understand that I found this post by Ulrik where he finds it's relatively few people who can't get a satisfactory shave from even such an obtuse angle. Now that I've been more relaxed about that I've certainly enjoyed the shave from other blades at, around, oh, 18 degrees or so. The Koraat though is still not my favourite and maybe the angle contributes there.

[–] gcgallant 1 points 1 year ago (1 children)

I typically don't worry too much about bevel angle when sharpening a razor. Mostly, I worry about alignment. In my experience, as you remove material at the edge you also reduce your ability to take away small edge alignment issues by rolling the edge on the stone. So you're left with grinding on the spine and the Sharpie trick to get a reasonably equal bevels on both sides of the blade. And when you're grinding on the spine, adjusting the area of hone wear becomes important as it starts to exceed the bevel area. As I'm sure you know, this can be hours of work.

That's a very interesting post by Ulrik. I have two of his razors; a 7/8" near wedge and a 6/8" full hollow that is a scaled down 14-2.0. (a "13-2.0"). Of these, I much prefer the feel of the 6/8". The 7/8" feels like my other wedge-grind razors. The wedges aren't objectionable to me, but I get better shaves from my full hollow razors. I hadn't thought of it until now, but maybe, as a daily shaver, the narrower bevel angle makes it easier to remove one day's growth.

[–] HomeAwayFromHone 2 points 1 year ago (1 children)

In my experience, as you remove material at the edge you also reduce your ability to take away small edge alignment issues by rolling the edge on the stone.

Hm, if anything doesn't uneven hone wear / bevel help compensate for the twist or bend of the blade? You're essentially grinding it flat. But of course many are too bent for that and you'll ruin it if you don't roll your stroke but I don't quite follow how the wear will hinder rather than aid that process?

Having everything symmetrical is a nice goal as it means your strokes are lining up just so with the curve of the blade (and none of them are completely straight despite the name), but the thing the really matters is that the edge is making contact the whole way along. Hence the sharpie trick being so key.

And when you’re grinding on the spine, adjusting the area of hone wear becomes important as it starts to exceed the bevel area.

Well, that's the angle at that point right? The spine is wearing more slowly than the bevel and so it's getting more and more obtuse.

I do worry about angle to an extent (when it gets up around 19 or so, part of why I was hesitant to tape the blade I just posted for my Sunday SOTD to give it the microbevel that'll save me from having to spend forever fussing with it. But I'll probably just do that at this point, polyimide (aka Kapton) tape isn't very thick after all...

[–] gcgallant 2 points 1 year ago

Hm, if anything doesn’t uneven hone wear / bevel help compensate for the twist or bend of the blade?

Yes. I do the tap and wobble business to check overall razor geometry. If it is close, then my first strategy is to see if I can get even material removal from the bevel by rolling pressure through the edge. If this proves ineffective, then I'm left with spine work. But, if the edge is damaged to begin with, and material needs to be removed prior to sharpening, then rolling pressure might not be an option as there's just less bevel to manipulate.

Well, that’s the angle at that point right? The spine is wearing more slowly than the bevel and so it’s getting more and more obtuse.

Yes. Exactly. My understanding is that the goal is to have spine wear closely match bevel wear so that the overall sharpening angle is maintained for a long time. It's a very imperfect world with older razors. Often to get proper bevel geometry adjusting the spine results in more wear in some areas than others.