Kashering From Milchigs

Q. I have a very sharp milchig knife. It would be useful to use it to cut up a tough piece of meat. May I kasher the knife and use for this purpose?

A. The Magen Avraham (509:11) writes that the accepted minhag is to not use the same utensil for both milchigs and fleishigs even if one kashers in between. The concern is that one might forget the current status of the utensil and inadvertently use it for fleishigs when it is still milchigs or vice versa. The Magen Avraham suggests that this custom may be rooted in another Talmudic prohibition. The Gemara (Chullin 8b) states that a butcher should not use the same knife to cut kosher meat and forbidden fats. The Talmud asks why can’t the same knife be used by cleaning it between uses? The Talmud answers that the butcher may forget to clean the knife. By the same token, a person who is using a dairy vessel for meat might forget to first kasher in between uses. The Aruch Hashulchan (89:17) disagrees with the Magen Avraham. The minhag cited by the Magen Avraham has no Talmudic source, and apparently, he considered it a newly established custom. The Aruch Hashulchan maintains that later Poskim do not have the Rabbbinic authority to institute new “gezairos” (prohibitions). Rav Moshe Feinstein (Igros Moshe YD I:43:6) supports the Magen Avraham and proves that this custom was of ancient origin.

Poskim suggest various exceptions to the minhag of the Magen Avram not to kasher from meat to dairy. The Mishnah Berurah (451:19 and 509:25) quotes the Chasam Sofer who maintains that when kashering for Pesach, one may change the status of the utensil. The Maharsham (2:241) and Igros Moshe (YD I:43:6) permitted kashering from milchigs to fleishigs if the utensil had not been used in 12 months. There are additional suggestions for leniency (see Piskai Teshuvos 509:16). Consultation with your local Rabbi is advised.

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The Gerald & Karin Feldhamer OU Kosher Halacha Yomis is dedicated to the memory of Rav Yisroel Belsky, zt"l, who served as halachic consultant for OU Kosher for more than 28 years; many of the responses in Halacha Yomis are based on the rulings of Rabbi Belsky. Subscribe to the Halacha Yomis daily email here.