(urth) Fuligin invented

[gwern0 at gmail.com]

On 2008.01.17 12:20:21 -0600, Lane Haygood <lhaygood at gmail.com> scribbled 2.3K characters:
> I've never heard of an actual mercury channel in a sword. I can ask on
> a swordsmanship forum I frequent (where several smiths post) to see if
> it's feasible. From what I understand of sword structure, it's not.
> You need the center part of the sword to be the strongest part, and
> that usually means it needs to be softer and more ductile than the
> surrounding steel. Cutting a big channel out of the middle of it might
> weaken its structural integrity to the point where it would be useless
> for cutting.

When it was described, the way I thought it was done was like this: swords sometimes have 'blood grooves' (fullers), right? This produces a slight volume down the middle which you could fill up - maybe you could weld a flat strip down the length of the blade, or fold over a section of the blade and create a sealed space that way. To make it symmetrical you could either do the same thing to the other side (if the blade in cross-section kind of looks like an I-beam), or have just a single fuller/mercury-channel. It'd be very tricky to have a good welded channel or to preserve the void while working it in the other method, yes, but it doesn't seem impossible to this layperson. :)

> The idea is that the edges, the parts that need to be sharp, should be
> harder. When steel hardens, it becomes more brittle. Brittle steel
> will sharpen and hold an edge. But it's also weak. If you made the
> whole sword out of really hard steel it would chip and shatter
> whenever it made contact with something. So you make the non-edge part
> of the sword out of softer, more flexible metal so that it will
> actually absorb shock. But cutting a big channel out of the middle
> would remove a lot of the shock-absorbing material.
>
> Lane

I don't think fullers are always cut - <https://secure.wikimedia.org/wikipedia/en/wiki/Fuller_(weapon)> says you could also just press or bend the blade.

--
gwern
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