Can I Kasher my oven from Fleishig to milchig?
June 5, 2019
Beis Moshiach in #1169, Halacha 2 Go, Mivtza Kashrus, Shavuos

A collection of frequently asked halachic questions regarding the custom of eating dairy foods on Shavuos, from &

By Horav Yosef Yeshaya Braun, Mara D’asra and member of the Crown Heights Beis Din

When Kashering an Oven from Fleishig to Milchig is OK

It is a minhag (custom) among Ashkenazim to avoid kashering from milchig (dairy) to fleishig (meat) and back again; one of the reasons for this is that were someone to do this on a regular basis, dilma asi l’mit’ai (perhaps one will make a mistake [and won’t remember the current status]). B’dieved (after the fact), if a kli (utensil) was properly kashered from one type to the other, it is considered kosher.

According to most poskim, kashering through libun (purification [through fire], i.e. the most stringent manner of kashering) is excluded from this minhag. Specifically an oven—which is usually preheated, and therefore kashered in a simplified manner for each use—would cause less issues in case of a mix-up. However, some poskim still maintain that kashering keilim through libun should also be restricted by this minhag.* (Practically speaking, an oven is the most common kli to undergo such switch-offs and is often the source of slip-ups.)

Since not changing the status of a kli from milchig to fleishig (or vice versa) is a minhag and not a clear-cut halacha, there are many exceptions to the rule:

B’sha’as had’chak (in pressing circumstances) it is permitted to make the change.

When kashering for Pesach it is permitted to switch the use of a kli and have it remain the new status year-round.

A permanent change to the status of the kli is also acceptable.

Twelve months of no dedicated usage: if no fleishigs was cooked in all that time—then a utensil or dish that was formerly fleishig may be converted to milchig, or vice versa.

A second-hand kasherable gift that is the opposite status of the recipient’s needs, may be switched from one type to the other upon receiving it.

A kli which has an indefinite status: if the current user does not know whether it is milchig or fleishig, it may be kashered to be used for the desired status for the long-term.

A dish or cooking utensil that became treif may be switched to the alternate usage upon kashering it.

One way to transform a kli that does not fall within any of these exceptional circumstances is to purposely make it treif in order to kasher it. However, since we are prohibited to mix milk with actual meat, the mixture should be of chicken and milk—for example, pouring hot chicken broth on the milchig kli. In the reverse situation (since most fleishig dishes are used for chicken and meat indiscriminately), the kli would have to sit twenty-four hours unused before pouring hot milk on it—unless it is indeed a utensil used exclusively for fowl.

It is also permitted to switch between milchig and pareve, or fleishig and pareve. So an oven that was fleishig and was subsequently kashered to pareve, may afterwards be made milchig—or the other way around—though this should not be done on a regular basis.

When should one get his hair cut before Shavuos this year?

It is a Mitzvah to have hair cut before every Yom Tov, so as not to enter into Yom Tov unkempt. The prohibition of haircutting on Chol Hamoed was instituted especially to compel people to receive a haircut prior to Yom Tov and not to postpone it.

The necessity of receiving a haircut on erev Shavuos is more acute, because haircutting was prohibited throughout Sefirah. The long hair accumulated over Sefirah causes a disheveled appearance, which is highly inappropriate for any Yom Tov.

Minhag Chabad is to take a haircut only on Erev Shavuos (this includes the preceding night). However, since Erev Shavuos coincides with Shabbos this year, we must cut our hair one day earlier, on erev Shabbos. In his  Kovetz, Rabbi Dvorkin writes: “It is obvious to me for a number of reasons that [when Erev Shavuos  coincides with Shabbos,] one should receive a haircut on Erev Shabbos. In fact, I did so myself. And just as the barber began to cut my hair, his telephone rang –  it was Rabbi Chodakov calling. The barber then asked me if he could go immediately to give the Rebbe a haircut…”.

There has been extensive discussion whether this includes Thursday night as well. In practice, we may be lenient about this matter.


Short Q&A’s

Do I need a separate mixer to mix cheese cake or can I use a regular cake mixer?

If the blade or bowl do not become hot at all in the process, you may use the same mixer.

Can I eat salmon and Parmesan cheese together?

One should refrain from eating fish with milk since there is a danger involved.

It is proper to also refrain from eating cheese with fish. This applies only to hard cheese. The same applies with Parmesan cheese. However, this does not apply to butter or cream cheese.

The Tzemach Tzedek holds that if one adds butter or sour cream to the mixture there is no concern.*

* References and marei mekomos are available for this Halacha on the websites: and

Please note that these halachos apply in general situations. In unique circumstances, a different halacha may apply. If you are unsure whether the halacha applies to your particular situation, please consult a Rov.

Article originally appeared on Beis Moshiach Magazine (
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