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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?

msh210
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B111
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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 Dec 10 '16 at 23:12
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    https://he.wikisource.org/wiki/%D7%9E%D7%A9%D7%A0%D7%94_%D7%97%D7%95%D7%9C%D7%99%D7%9F_%D7%90_%D7%91 – Double AA Dec 10 '16 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 Dec 11 '16 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 Dec 11 '16 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 Dec 11 '16 at 17:26
  • I know it's halachically permissible. I'm wondering about feasibility. – B111 Dec 12 '16 at 08:01
  • Seems off topic as Jews not Judaism. The OP admits he knows the halakha and just wants to know if historically any Jews ever did. – mevaqesh Oct 08 '17 at 14:51
  • @mevaqesh I disagree. The OP admits he knows the Halacha and just wants to know if it’s actually possible to do it. That’s a question on Halacha. – DonielF Oct 08 '17 at 16:53
  • @doniel reread it. He isn't asking what the halakha would be. He's not asking about halakha, but about practicality and whether it was historically done. Halakha may perhaps form the backdrop for the question, but it isn't a question about halakha. – mevaqesh Oct 08 '17 at 19:33
  • @mevaqesh Reread what I said. I understand he’s not asking about what the Halacha is. He’s asking how practical this Halacha is. The fact that a historical account could be an answer doesn’t necessarily make it a question about history. And, of course, not all history questions are off-topic if they pertain to Judaism and not Jews. Here it would pertain to Halacha, which is certainly on-topic. – DonielF Oct 08 '17 at 19:36
  • The fact that am yisroel used flint in the desert for mila, doesn’t mean they used it for shechita. The halachos are very diferent and the purpose of the knives are diferent. Flint flakes and is naturally serated and sharp. That is a benefit for mila only, as the serrations would make it possul for shechita. As for availability, they had plenty of bronze, silver and gold that they took from Egypt. Any of those could be used for making a chalif. – DovidShaffier Oct 16 '17 at 04:42
  • @kouty obsidian is very diferent from regular glass. Glass can be melted and formed into a blade that is both sharp and smooth. Obsidian can not be remelted and shaped. Anything that makes shards is forbidden because of ikkur. Glass can also be sanded smooth by hand whereas obsidian can’t be. – DovidShaffier Oct 16 '17 at 04:47
  • @B11 Rosh hashibolet is “mistabech betzbah”. Anything you can feel with your nail is “ogeres tziporen”. The serrations on obsidian are definitely ogeres tziporen. – DovidShaffier Oct 16 '17 at 04:53

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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.

DovidShaffier
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  • I believe that obsidian was used up until the mid 1800s – mroll Oct 09 '17 at 02:59
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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 Oct 10 '17 at 05:16
  • @DovidShaffier Interesting. Do you have a source for that? – Oliver Oct 10 '17 at 15:20
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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 Oct 16 '17 at 04:12
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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 Oct 16 '17 at 04:15
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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 Oct 16 '17 at 04:20
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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 Oct 16 '17 at 04:25
  • @DovidShaffier according to the Rambam, as long as they have a consistent texture (he says like a head of wheat,) it's fine. – B111 Oct 16 '17 at 07:35
  • Everybody says that “like the head of the barley” is fine. But they’re referring to the feeling of its edge on the skin, Not on the nail. Until recently shechita knives were checked on the skin first. If consistency was the only atribute that mattered, you’d be able to shecht with any bread knife. The maximum Shiite of a pegima that anyone allows is any thing that catches the nail. But today we are makpid to go according to the opinion that any discernible pegima is possul the shechita. And by we, I mean all the poskim and shochtim today. – DovidShaffier Oct 16 '17 at 19:25
  • There is a difference between pegima, hergesh and shinui. – B111 Oct 17 '17 at 05:10
  • What about Tungsten? Being one of the hardest metals in existence, it would stay sharp forever at the moment of its crafting. – eternalsquire May 01 '23 at 15:29