Thread: Can a razor be too sharp?

Originally Posted by khaos

This is slightly wrong. The triangular profile where the edge meets will always be a consistant width (if we are assuming it is triangular aka perfect honing, not round tip). However, if you look at it side on, there will be a lateral profile (at the microscopic level) like a very complicated sine wave! JOY!

Now, as I am learning at college, one can explain this with... FOURIER SERIES! If we assume the scratches on one side are regular, with period x, and on the other side, with slightly different period 1.000001x, but out of phase, then the sum will give you a very different sine function, which will be the edge profile. Now, the scratches on a large grit will not be consistant, they will have underlying frequencies and require fourier transforms of there own, (so imagine doing this with something like 4cosx+3sinx+19cos2x+2sin2x+7cos3x...) and as you can imagine, it would be highly implausible that two sine functions that look like that will add up to give you a straight line. However, as the grit becomes smaller, your scratches are smaller (lower amplitude of variation) and more consistant (simpler transforms, fewer underlying frequencies) and so matching the periods will come closer to a straight line (due to simpler transforms) and will have less deviation along the edge (due to lower amplitude). YAY! I bet none of that made sense to anyone, but at least my thousands of dollars spent on education finally turned up a little bit useful...



In theory this is right, but would only be true if every stroke were in exactly the same place, which would be statistically implausible (the politically/scientifically correct way of saying impossible). One stroke you may form peaks/valleys along a(x)=ysin(zx), the next stroke would maybe be b(x)=ysin(zx)+.000000001, the next would be c(x)=ysin(zx)+.0000000004, etc. Eventually, if every stroke were very slightly different (which it will be) you will reach an edge equal to the root mean square of the untranslated sine function, which mathematically speaking, is a perfectly straight line equal to Fsum(x)=y*sqrt(2). (Variables: a,b,c, etc are the terms of the fourier series, Fsum(x), which is the overall edge profile. x is the position along the length of the edge, y is the grit of the hone, and z is the fourier transform of a hone's particular profile frequency)
Think of this like electricity. The wall socket is constantly alternating at Fsum(x)=110sin(30x/pi) (60 hertz period, 110V amplitude). This means you are in theory only recieving electricity some of the time. Sometimes you are at peak voltage of 110V, but 60 times every second that number dips negative. Now it would be a bitch to calculate your energy bill if they had to integrate the function of your power consumption. But they don't have too. Because we use so much power, and not just at 2 second increments, they just charge us the root mean square of 110sin(60) times the amount of power we draw. (the point of this analogy was to demonstrate the root mean square idea.) So yes, you could reestablish valleys, but the world is not perfect, so you can't really polish too much, unless you are overhoning.
Also, this begs the question, won't sharpening 500000 laps on a 4k do the same thing? No, because of the high grit, it "gouges" rather than gently scrapes. The last pass will always leave a slightly more distinct profile. This profile on a 30k will be a **** ton smoother than on a 4k.

Honemeisters please correct me as experience trumps explanation, but from what I've read, Glen agrees. It can only get so sharp, but you can polish it to be smooth which translates interestingly enough into literally a comfortable smooth shave.

Khaos,

I actually completely understand what you are saying (but I didn't break out the calculator to double check the math)
It makes complete sense, though, and is in line with the same thinking.

I tried to look at the edge straight on with my microscope, but couldn't get a good focus to see if the edge was even, or how even it is. Someone else may be able to...

Geez I hate math---LOL!

Jaguar really great razor. will get scary sharp

Originally Posted by hi_bud_gl

Jaguar really great razor. will get scary sharp

Wow, that is a gorgeous razor. Even better that it gets nice and sharp!

Sham that is a beautiful razor! I've never heard of that brand before. German I guess?

I have a few razors which are crazy sharp, but not all shave equally good.

1. FWE Special, this blade makes hair disappear no noise their just gone when doing hht, and shaves great.
2. Joseph Rodgers another scary sharp edge and shaves great.

3rd Johan Engstrom frameback wedge. Probably the sharpest edge I've seen
Sadly one of the worst shavers imho, feels like a cheese grader on my face.

I am not sure how this applies to this topic other then to me sharpness is only worthwhile when coupled with smoothness or shaveability.

Cheers
D

Originally Posted by Gunner777

German I guess?

I have a French razor just like that except Spanish point, and I have seen a few TI's exactly like that, with several different points. My guess then, though Sham has to say, that it is French usign Sheffield steel (all the TI's were stamped with something like "finest Sheffield Silver Steel". Plus the blade marking is French. Am I right?
PS: I still think this is more evidence that there was some connection between all the companies... a common supplier, them buying eachother out, a common grinder, etc...

Originally Posted by khaos

This statement is true. The edge cross sectional profile will be consistant, due to consistant material properties in the steel (hopefully) and consistant bevel setting (lets say lynn honed it first). However, as you polish it, you are bringing that edge closer to a straight line ie. smoothing it. So while all edges are sharp, a 4k edge will look like a mountain range under an electron microscope due to pjrage's explanation. So all those peaks will be creating scratches at the cellular level, giving a harsh shave. See? Glen knows his stuff. Sharpness shouldn't change (unless there is a big boo boo), but smoothness can vary a lot based on honing.

I think *think not know* that you could in theory break in a razor on the strop or your face, as the more you use it, the "peaks" will wear away faster than the "valleys" as they are not supported as well by the surrounding steel (less steel is around them as they jut out, while the valleys I would assume are very stable) However I would prefer a gentle smooth edge off the hone that having to break it in forever at my face's cost...

This is true in practice too AFAIK,,,,,,

To smooth out a harsh edge or to get the absolute smoothest edge on a razor try this...

Bring the razor to the best level you can, shave twice with the edge then use the top end stone or paste you used in the first place 1/2 the amount you used in the first place...
ie:
My finish was 20 laps of CrOx so the re-finish would be 10 laps of the same...

Then re-strop as you did coming off the hones and see what happens....

Some of us have been using this trick for years, if you search way back you will find where I posted it, and then again where Poona posted it.... Possibly it was posted even farther back than that....

My theory was that the shaving let the steel be "microscopically abraded" then you re-smooth that up... I don't know if that is true, but I do know it works....

yes razor made in France. i really didn't know what is it at first. i thought it is puma someone corrected me and said no it is Jaguar.

Oh ok----I know the French and Germans are fond of using the word Jaguar to name a host of things.