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I'm learning shechita and was wondering whether anyone has tried using obsidian or titanium for shechita.

It seems that due to the hardness of the material in the case of titanium and the tendency of obsidian to flake would make the knives less susceptible to pgimot (blemishes).

On the other hand, maybe it would make the blades harder to sharpen.

Thoughts?

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  • Isn't obsidian "charvos tzurim" which were used in Mitzraim? While it does say for milah, the implication would be that it is what was used for shechitah as well since it is what they had available.
    – sabbahillel
    Commented Dec 10, 2016 at 23:12
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    he.wikisource.org/wiki/…
    – Double AA ♦
    Commented Dec 10, 2016 at 23:21
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    Please explain, How does the tendency to flake help? If it flakes is it not a probability that it will pinch and pull instead of cutting
    – hazoriz
    Commented Dec 11, 2016 at 11:01
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    As I understand, it flakes along with the grain, rather than chipping perpendicular to the blade. Therefore, you won't get pgimot, which catch the flesh. You'll get a texture, but the Rambam says that this is okay ("like a rosh shibboleth") as long as the texture is constant.
    – B111
    Commented Dec 11, 2016 at 12:14
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    In Shulchan Aruch YD Siman 6 sayf 1 בכל דבר התלוש שוחטין. בין בסכין בין בצור בין בקרומית של "קנה–האגם" הנקרא אחשפדני"א (או שן וצפורן יחידי. טור) וכיוצא בהם מדברים החותכים. why not titanium, obsidien is volcanic glass and Shach SK 2 said that glass (" זכוכית") is OK
    – kouty
    Commented Dec 11, 2016 at 17:26

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I make chalafim for a living. Neither is feasible. Titanium is not a knife metal because it can’t be sharpened. It’s only considered to be strong in relation to its weight. Titanium is very light, so it’s useful for some industrial projects but is very difficult to grind even on professional machines. Should one attempt to sharpen it anyway, they’d find that it will never achieve a sharp edge. Obsidian is too brittle to make a shechita knife from. Any matarial that sheds shards can cause ikkur in the simanim. It also is not a matarial that can be sharpened and smoothed. While Chazal permitted the use of a knife that’s edge is similar to “Rosh Hashibolet”, The Halacha today is to forbid it. (Rema on yoreh deah simian 18, sif vav) Knife makers spend years researching the best metals for each type of knife they make. Shechita knives are amongst the hardest knives to produce. It would be technically impossible to manufacture a chalaf out of either titanium or obsidian.

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    Where are you getting that from? In around the late1750’s The Ba’al Shem Tov (re)introduced high carbon steel for use in shechita knives. Before that, mild carbon steel or iron was used.
    – DovidShaffier
    Commented Oct 10, 2017 at 5:16
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    There are many letters and responsas on the subject from the time. One source is the addendum to shulchan aruch Harav, Hilchos shechita. There you’ll find several letters on the subject.
    – DovidShaffier
    Commented Oct 16, 2017 at 4:12
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    You can also look at the famous cherem against the chassidim in which changing the shechita knives was one of the major concerns listed. The Gemara states that the shechita knives in the beis hamikdash were made out of steel from India. At the time India was one of the only places in the world producing high carbon steel. That’s the reason Alexander the Great didn’t conquer them, since they gave him wagon loads of high carbon steel.
    – DovidShaffier
    Commented Oct 16, 2017 at 4:15
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    Until around 1750 high carbon steel wasn’t available in Europe, until someone in England invented a method to produce it commercially. Not long after that the Baal Shem Tov decreed it should be used for chalafim in Eastern Europe. (German shochtim had already been using it for several years). I’ve done extensive research on the subject for the next addition of my Sefer “Esek Hashechita”. This forum is too brief to list all the sources I’ve discovered, but I can assure you obsidian was never commonly used for shechita knives.
    – DovidShaffier
    Commented Oct 16, 2017 at 4:20
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    Also, obsidian knives are sharpened by flaking off a layer of stone by the edge. They always have a fine serated edge, so they would always be forbidden for shechita.
    – DovidShaffier
    Commented Oct 16, 2017 at 4:25

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