View source for Knives That Cannot Be Used for Shechitah

''For the more general knife ideas, see [[The Shechitah Knife]].''
==Invalid Knives==
===Pegimot===
# A knife with a pegima (nick) may not be used. Bediavad, if one used it and claims he didn't use that part of the blade, the meat is kosher, but if he didn't realize it was there until afterwards, he has no claim.<ref>Simla Chadasha 6:3</ref>
# Ideally even if one covers the pegimah, he might accidentally use the part with the pegimah.<ref>Simla Chadasha 6:3</ref>
# If the blade has two edges, one must make sure both are free of pegimot.<ref>Simla Chadasha 6:3</ref>
# On Yom Tov or in pressing circumstances, one can cover the pegima and shecht carefully, avoiding the pegimah, as long as there are two neck widths of length left of the knife from the pegimah in either direction and one shechts in a sawing motion. Some say the length is measured from the end of the cloth and not the pegimah. All this applies for two pegimot with enough blade length in between, as well.<ref>Simla Chadasha 6:3</ref>
===Glowing Hot Knife===
# A knife that is heated till it glows (incandescent) may not be used, as the heat from the sides of the blade burns the simanim before the blade finishes severing them, resulting in a piercing instead of a shechitah. The meat would be prohibited on a Torah level. Some are lenient bediavad if the shochet was aware and maneuvered the knife in a way that avoids the sides touching the simanim, but the halacha follows the strict view. Some say the minimum temperature of the metal is Yad Soledet Bo.<ref>Simla Chadasha 9:1</ref>
===Non-Kosher Knives===
''See [[Koshering a Kitchen]] for more details.''
# Due to the temperature of the animal neck and potentially also to the pressure of the knife, one may not use a non-Jew's knife before kashering it or sanding down a layer from both sides of the knife. Hagala is sufficient unless there are holes in the blade, which would then require libun.<ref>Simla Chadasha 10:4</ref>
# Although shochtim bring their own knives to the slaughterhouse, there is still an issue sterilizing their knives in the hot water "baths" the USDA requires slaughterhouse equipment be dipped into.<ref>Rabbi Dovid Cohen from the cRc in [https://crckosher.org/videos/cleaning-chalif-between-shechitos-meat-and-poultry-9/ Cleaning Chalif Between Shechitos (Meat and Poultry 9)]</ref>
====''Ben Yomo''====
# If it was definitely used for non-kosher in the past twenty-four hours (''ben yomo'') but not kashered, a layer must be sliced off (''kelipah'') from the neck, due to the potential for non-kosher substances on the blade to rub off and be absorbed in the neck and because generally these things are not absorbed deeper than a kelipah.<ref>Simla Chadasha 10:5-7</ref>
# Whereas if the blade was properly cleaned of surface substances with neitzah, one would think this halacha does not apply, some argue that even if so, there's still a concern for absorption of flavor facilitated by the heat of the animal neck and the pressure of the blade. Moreover, there may still be hard to see non-kosher substances still present on the blade.<ref>Simla Chadasha 10:5</ref> 
# Without kelipah, cooking the meat would require measuring if the kelipah is less than one sixtieth of the rest of the meat and then kelipah.<ref>Simla Chadasha 10:6</ref>
# In circumstances where kelipah is required, one may not shecht with intention to afterwards do kelipah; if the kelipah would just be a stringency, then it is ok.<ref>Simla Chadasha 10:8</ref>
# Washing the knife is insufficient to remove the adhering non-kosher substances.<ref>Simla Chadasha 10:9</ref>
====''Eino Ben Yomo''====
# If the animal was shechted with non-kosher knife that was not used for non-kosher food in the past twenty-four hours (''eino ben yomo''); although the knife should have ideally been kashered, the meat is kosher. The same is true if one is unsure if it was used in the past twenty-four hours. If there is any visible non-kosher substance on the blade, as knives are often not perfectly clean, then the rules of an actual ''ben yomo'' must be followed. Even if one thinks it was clean, there's room to be strict, unless one made sure to do a thorough job or it is a pressing situation.<ref>Simla Chadasha 10:7</ref>
# Regardless, one is not allowed to use an eino ben yomo lechatechilah unless he kashers it first. Bediavad with neitzah ten times (and no less) the meat is permissible, but, ultimately, in all circumstance, a scrupulous person should strive to do kelipah regardless.<ref>Simla Chadasha 10:7</ref>

===Knives Used for Idolatry===
# One may not benefit from tools used to worship an idol, therefore, the knife used to slaughter animals for idolatrous sacrifices is prohibited from benefit. That said, killing a healthy animal is arguably more detrimental than it is beneficial, as the animal is no longer alive to grow or work. A dead animal is only good for its meat and entails a necessary loss. Similar arguments could be made for birds. As such, shechting a healthy animal or bird with a knife used for idolatrous activities is permissible, because causing a loss is not considered benefit. However, a sick animal may not be shechted with that knife, as that would be considered an improvement. Some argue the same is true for a very violent or high maintenance animal that comes at a loss to its owner or if the price of meat is higher than the price of the animal it comes from.<ref>Simla Chadasha 10:1</ref>
# If the knife was used to cut wood which was then used for idolatry, then it's permissible. It's only considered a knife of Meshamshei Avodah Zarah when the idol is finished with the knife or sacrifices are slaughtered with it.<ref>Simla Chadasha 10:2</ref>
# A sick animal slaughtered with a knife of Meshamshei Avodah Zarah is entirely prohibited from benefit until one throws away enough meat the value of which is equal to the cost of shechting with it. If there aren't any more knives avaialble, then the cost of shechting must go up.<ref>Simla Chadasha 10:3</ref>
==Sources==
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[[Category:Shechitah (Kosher Slaughter)]]
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