The Israel Koschitzky Virtual Beit Midrash

A WEEKLY SHIUR IN HALAKHIC TOPICS
Yeshivat Har Etzion

Translated and adapted by Rav Eliezer Kwass

KASHERING MICROWAVE OVENS

For a discussion of how microwave ovens work and the differences between them and normal electric ovens, see Professor Zev Lev's article in Techumin volume 8. In this context we will summarize his suggestion for kashering microwave ovens. We will follow with an alternate suggestion offered by the Tzomet Institute in their introduction to that volume.

Professor Lev:

The whole inside surface of the oven, including its walls and door, should be cleaned thoroughly of even the slightest remnants of chametz. The oven should be left unused for twenty-four hours. Afterwards water (preferably mixed with detergent or some other inedible material) should be boiled inside the oven until the walls reach their maximum heat. The oven is then ready for Pesach use. The main reason for the boiling is to remove any chametz that got absorbed into the walls of the oven.

One should take care to cook things in the microwave with a cover; this reduces the chance of them absorbing any chametz that may be expelled by the walls of the oven. During the rest of the year covering everything used in the microwave enables it to be used for both meat and milk dishes. (In my opinion both meat and milk dishes should be covered.)

The glass plate that food is placed on can be treated like glass vessels and be kashered through "hag'ala" done by soaking in water for seventy-two hours with a change of water every day. For those who are stringent and do not kasher Pyrex, the tray should be switched for Pesach (Sefaradim can certainly kasher it through "hag'ala", and perhaps Ashkenazim can as well.)

Tzomet:

A microwave can be used on Pesach if the food being cooked is placed in a container within another container. The closed food container should be placed within a larger container (a large refrigerator storage container, or even a cardboard box that fits the dimensions of the oven). Before using the oven on Pesach, the microwave should be cleaned well and not used for twenty-four hours.

The box should not be open to the inside of the oven.

KASHERING DISHWASHERS

Much has been written on kashering dishwashers for Pesach and using them for both meat and milk (see Techumin volume 11). The following is what appears to me the most sensible suggestion.

Using For Meat and Milk

In order to wash meat and milk utensils one after the other: One should wash off the utensils from significantly sized remnants of food (it is preferable that all visible food be washed off). Different trays should be used for meat and milk. Since the trays usually have direct contact with the food on the utensils, using the same trays might require complete "hag'ala" between meat and milk. Likewise, the strainers at the bottom of the machine should be cleaned well between meat and milk washings.

This lenient approach is well-based (see the source material brought in Techumin 11):

1. In general there is not so much actual food left on the utensils, and it is most likely negated one in sixty ("batel be-shishim").

2. Furthermore, the detergents used in the wash mar the taste of the food, transforming it into "ta'am li-fgam" (taste that has been rendered inedible).

3. One can also assume that the walls of the dishwasher do not absorb food directly, but only through the medium of the water (known in halakha as the "ta'am," the "taste" of the food - this is usually contrasted with "be-ein," the food itself). Only a pale remnant of meat ("ta'am") that has been absorbed in the walls of the dishwasher mixes with the milk that has been similarly absorbed. This is a mixture of only "notein ta'am bar notein ta'am de-heteira," meaning that not even the "ta'amim" of the meat and milk mix directly ["Taam" of meat gets absorbed in the walls of the dishwasher, then, when expelled from the walls] during the washing, it mixes with "ta'am" of milk. "Basar be-chalav", the prohibited mixture of meat and milk, cannot come into existence from such a weak mixture.

I find it hard to permit washing milk and meat vessels together, though. Similarly, it seems that one needs separate trays for meat and for milk. Some require that the dishwasher be run empty between meat and milk in order to perform "hag'ala," to remove the meat or milk from the walls of the dishwasher. As I have said, I do not think that is necessary, and it seems that that is not common practice.

Kashering for Pesach:

The trays, strainers, and any other removable pieces should be kashered through normal "hag'ala" in boiling water in a "keli rishon" (vessel with water cooked directly on the fire). [Large trays can be kashered in the large kashering pots set up all over Israel before Pesach.]

The walls of the dishwasher also require "hag'ala" to remove the chametz absorbed in them. Rav Moshe Feinstein z"l (Igrot Moshe YD 3:58) rules that the dishwasher should be kashered in a way that the water inside of it reaches a temperature slightly higher than that of the water that is normally used in it. The dishwasher should not be used for twenty-four hours, then it should be put on its highest setting and run, preferably with detergent inside. He suggests that ideally ("me-'ikar ha-din") hot iron should be placed in the water to make it boil (the water in a dishwasher usually only reaches 60-65 degrees Celsius, 140-149 degrees Fahrenheit). This is, of course, very difficult to execute, nor does it ensure that the water will boil. However, Rav Moshe added that this extra step is only ideal.

It seems that the principle being applied is "ke-vol'o kakh polto," removing material in a manner similar to the way in which it was absorbed. Therefore, the "hag'ala" can really be performed at the highest temperature of the dishwasher. To make sure that this actually happens it makes sense to heat the water slightly higher than normal. This could be accomplished by boiling water and throwing it in with the water in the dishwasher. Then it will definitely reach the highest possible temperature at which anything might have been absorbed.

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For direct questions or comments to Rav Mordechai Friedman, the list coordinator, please send email to mf@etzion.org.il .

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