Aino Ben Yomo - Pre-Seasoned Cookware

QUESTION: I bought a brand new pre-seasoned cast-iron skillet. Is there any reason why this must be kashered before it may be used?

ANSWER: Pre-seasoned pans have a coating of shortening or fat that has been applied by the manufacturer. This layer of fat is baked onto the surface of the pan to create a protective barrier to prevent the iron from rusting. This presents a kashrus concern, because shortenings and fats can be derived from either animal or vegetable sources. Even if the company asserts that they only use vegetable fat, this is still problematic because, a) they do not have halachic credibility, and b) because uncertified oil may be non-kosher if it was refined on the same equipment as animal fat. As such, a pre-seasoned cast iron pan must be kashered before it is used.

What method of kashering is appropriate - libun or hagolah? It might be thought that hagolah is adequate because the oil melts in the pan during the seasoning process. As such, the cooking takes place with liquid, and hagolah should suffice. However, the Pri Migadim (Mishbitzos Zahav, OC 451:16) suggests that libun may be necessary when frying with non-kosher fat because the fat was solid when initially applied.  

Rav Belsky also recommended kashering a pre-seasoned pan with libun for a practical reason. A seasoned pan has a layer of fat that is baked onto the outer surface. The fat forms a visible barrier which cannot be washed off with soap and water. An effective and simple way to remove the fat is to put the pan in an oven during a self-cleaning cycle. This will be considered libun, and both the absorbed and outer layers of fat will be removed at the same time.

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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.