Sunday, May 17, 2009

Kashering from Meat to Dairy (and Vice Versa)

I. The Custom

The Magen Avraham (509:11) records a custom not to kasher utensils from meat to dairy and vice versa. Even though it is technically allowed, the custom developed not to do it. Kashering is for utensils that, for whatever reason, become non-kosher and need to be purged.

The Magen Avraham offers a rationale for the custom in the name of R. Mordechai Yaffe: If you keep kashering a utensil back and forth between meat and dairy, you are liable to make a mistake at some point and use it for the wrong thing. He offers a talmudic precedent from Chullin (8b), that a slaughterer should have separate knives for cutting meat and cutting fat so as not to accidentally use the knife for the wrong item before kashering it.

II. Exceptions

Click here to read moreHowever, other authorities dispute that such a custom can exist. The Pri Chadash (Yoreh De'ah 97:1) writes that nowadays we do not create new "fences," new practices to guard against violations. Therefore, since it is technically permissible to kasher back and forth, it must remain permissible. This is also the position of the Arukh Ha-Shulchan (509:10) and, more recently, R. Ovadiah Yosef (Yabi'a Omer 3:YD:4). However, the majority of Ashkenazic authorities accept this custom as normative.

There are exceptions and ways to get around this custom, such as kashering a meat utensil and making it pareve for a time, and then using it for dairy. Or, as the Pri Megadim (Orach Chaim, Eshel Avraham 509:30) suggests, rendering a utensil non-kosher and then kashering it into whatever usage you want. Regardless, the question remains what the nature of this custom is. I'd like to propose two possibilities, and then we can examine the impact of these explanations.

III. Two Approaches

The first is that the custom is simply to maintain separation between dairy and meat utensils to avoid confusion. That seems to be the simple explanation, and the one that the Magen Avraham accepted.

The second is based on an explanation proposed by the Sha'ar Ha-Melekh (Hilkhos Yom Tov 4:8). He suggests that the custom is not of separation but based on the complex rules of kashering through hagalah, using boiling water. The Rishonim dealt at length with the dilemma this poses. At first glance, it seems like it should not work. When a utensil is placed in a pot of boiling water, the taste that was absorbed by the utensil is released into the water. But then it should go right back into the utensil! This should effectively undermine the entire kashering process.

IV. Hagalah

To solve this, the Rishonim advanced a few different solutions. One is to maintain the water at boiling temperature so that the water will only absorb and not emit. If a utensil remains in the water as it cools, then you have a problem. Another is to only perform hagalah on a utensil that has not been used for a full day, so that the taste the utensil releases and then re-enters it is weakened (pagaum). A third is to use enough water (more than sixty times the volume of the utensil) so that any taste that is released into the water is immediately nullified (cf. Tosafos, Chullin 108b sv. she-nafal; Rashba, Toras Ha-Bayis 4:4).

The above solutions have been accepted and are used in practice, particularly the last two. The Sha'ar Ha-Melekh suggests that just like we normally treat utensils that have not been used recently as if they had, as a stricture in case we get confused (gazeru eino ben yomo atu ben yomo), so too the custom is not to kasher through hagalah a utensil that has not been used for a full day so as not to become confused and kasher with a utensil that has been recently used. With a meat or a dairy utensil, we can continue using it for its designated purpose. However, with a utensil that has been rendered non-kosher, we cannot use it for anything so we are not strict. Therefore, the custom has developed not to kasher a meat utensil for dairy use and vice versa, so as not to accidentally kasher such a utensil within a day of its most recent use.

V. Meat-Dairy vs. Non-Kosher

However, R. Ovadiah Yosef (ibid.) asks a very difficult question on this position. He points to the Bach (Yoreh De'ah 121) who explains that, really, you should be allowed to kasher a meat utensil within its first day after use because of the technical reason of nat bar nat de-heteira. However, you are not allowed to do it because you might get confused and also kasher a non-kosher utensil, which is not allowed. But if that is the case, asks R. Yosef, how can we have a custom not to kasher a meat utensil for dairy use based on a concern we might kasher within the first day when we don't have such a concern regarding a non-kosher utensil? The whole reason to prohibit kashering a meat utensil in the first day is because of a non-kosher utensil!

VI. A New Approach

I'd like to suggest a new approach that is based on the Sha'ar Ha-Melekh but slightly different. We discussed above the difficulties in performing hagalah and the ways in which we avoid the problem of the taste going out and then coming right back in. It could be that the custom that developed is that, in regard to changing utensils from meat to dairy (and vice versa), we do not rely on these solutions. Why? Because it is easy to get confused and use a meat utensil for dairy (or vice versa), we are stricter than the normative ruling and reject the approaches to allowing hagalah.

In other words, either the custom is 1) to maintain separation or 2) to reject the concept of hagalah.

VII. Practical Differences

Here are some differences that result from these two approaches:

1. Kashering through libun (contact with fire). According to the first approach, any kashering, even through libun, should not be allowed. According to the second approach, only hagalah is rejected but libun is allowed.

In practice, the Pri Megadim (Orach Chaim, Eshel Avraham 422:30) does not allow libun. The She'arim Metzuyanim Ba-Halakhah writes that the Magen Avraham (509:10) allows it but I don't see it there. It seems to me that he only allows it the specific case when every usage of the utensil begins with a libun, but otherwise forbids it. The Sha'ar Ha-Melekh (ibid.) allows it, as do a number of other authorities quoted in Darkhei Teshuvah 121:59.

Note that this is very relevant when it comes to kashering ovens and boilers.

2. Bedi'eved -- what if you already did it? Since this is a custom, it does not seem proper to punish those who already did it and forbid the use of the utensils. According to the first approach, it would seem that while you were supposed to maintain separation, once you kashered the utensil it can be used. However, according the second approach, the custom is to reject the hagalah so even if you kashered it, we don't view it as being kashered.

However, since there are those who reject this custom, it would seem that bedi'eved we can rely on them regardless of the approach we take.

The Maharsham (Responsa 2:241) permits the utensil to be used according to both the Magen Avraham and the Sha'ar Ha-Melekh.

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