Play-by-Play: The Case of the Non-Kosher Oven
Scene: A newly married couple in their tiny kitchen on their first day of “real life.”
She: We have a problem.
He: [Coffee cup clatters to the table] What is it!?
She: I don’t know whether our oven is kosher or treif (non-kosher).
He: [sighing with relief] Then let’s kasher it. Let’s see: libun kal (light purging by fire) would mean heating it up to at least yad soledes bo (the temperature from which the hand recoils) or perhaps to the point that kash nisraf (a straw burns). Maybe libun gamur (complete, red-hot purging by fire), just to be safe. [Stands up and fiddles around] The oven’s not self-clean, which would’ve made it really easy ... Let me go buy a blowtorch. I’ll call my chavrusah (study partner) at the kollel (Yeshiva for married men) on the way and let him know I’ll be late.
She: Wait! We can blowtorch the metal grates, sure (outside on the porch, please!), but the oven walls themselves—they might get ruined.
He: You’re right, blowtorching the entire oven is not really an option. Hmm, some people say that turning on the oven for an hour or two suffices—k’bolo kach polto (as it absorbed it is expelled), so since the non-kosher food was cooked in the oven at a normal cooking temperature, we can just turn up the fire to the highest setting for some time—
She: Hey, I learned that in sem (short for “seminary”—a post high-school institution). But I think that works only if just non-kosher steam was absorbed by the oven. People generally do cook in pans, but who knows if anything ever spilled on the inside of the oven while cooking? If it did, then the oven absorbed solid treif. It needs to be burned out with a proper libun.
He: Right. It needs to get red-hot or set off sparks and that requires … a blowtorch. But—wait that’s my chavrusah calling … [Comes back minutes later and takes a quick peek in the oven] I told him the whole story, he says if our oven is enamel—and it is—it’s already an issue, because it can be considered kli cheres (earthenware) which can’t be kashered according to halachah.
She: Is that right? I’m pretty sure we kashered our enamel oven back home from fleishig (meat) to milchig (dairy) when we got that new pro-range a few years back. My father said we can’t do it for Pesach, when we’re more machmir (halachically stringent) on kashering, but otherwise it’s okay.
He: Okay, I’ll call my chavrusah back [talks quietly in the phone for a minute and then listens for five, going over once to look closely at the inside of the oven] … He looked it up—he says you’re right, and we can kasher the enamel, but there’s another issue. Since the heating element is underneath the oven cavity in a separate compartment, it is considered heseko mibachutz (it is fired from the outside), so I don’t know if we can even kasher such an oven.
Both: We’d better call the Rav.
Conclusion
He: [walking in at the end of the day for dinner] I spoke to the Rav all about our oven. He said that if our oven would be non-kosher, only some poskim say it suffices with libun kal on the walls and blowtorching the grates. And if we had wanted to follow those who rule more stringently based on all the issues you and my chavrusah brought up, we’d have a real problem. But libun kal is sufficient to kasher an oven that only had kosher food, say it was used for milchig and we want it to be fleishig—or even if it became treif through baking both milchig and fleishig kosher dishes one after the other (though not at the same time). In these cases, there is halachic leeway to use the oven’s heating element even though it is heseko mibachutz, but if we wanted to be extra careful, we can place a disposable pan filled with water while it heats up, which will simultaneously kasher the oven from inside via steam. [Smiles broadly] We’re good.
She: Wait. How do you know that the high temperature option is enough? What’s if our oven is really treif, like non-kosher, from a previous tenant?
He: Oh, I called the landlord after I spoke to the Rav. He said the apartment was renovated six years ago and got a new oven—and the two renters since were, quote: “Other nice Orthodox couples like you.”