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The Quintessential Kashering Primer

For the Pesach-phobic, Dovid Cohen presents the basics of preparing the Pesach kitchen.

Rabbi Cohen is an OU rabbinic coordinator.

Copywrite © 2004 Orthodox Union
Reprinted with permission from Jewish Action, the magazine of the Orthodox Union; from the Jewish Action Spring 2004/5764 - Volume 64, No. 3
Also available online from the OU

One of the many preparations one must make for Pesach is kashering (a process to prepare a non-kosher vessel for kosher use or a chametz vessel for use on Pesach). Most people only kasher their utensils in preparation for Pesach; however, the following directions apply to kashering utensils year round as well. As with all areas of halachah, those who are unsure of how to apply the rules of kashering to their situation should consult with their local Orthodox rabbi.

General rules

There are two steps in kashering. 1. Cleaning—removing all tangible traces of chametz and 2. Purging— using heat to remove all absorbed chametz flavor.


All chametz utensils that will be used for Pesach must be thoroughly cleaned. This includes the removal of all food, rust, dirt, calcium deposits and anything else that protrudes; this does not include the removal of discolorations. Items that contain narrow cracks, crevices, deep scratches or other areas that cannot easily be cleaned, cannot be kashered for Pesach. Therefore, the following cannot be kashered:

Additionally, the common custom is to cover tables, counters, refrigerator shelves and other areas where one might not have been able to clean away every trace of chametz.


In addition to cleaning utensils, most items require some form of hot purging in order to remove the flavor that has been absorbed. As a rule, any utensil that came in contact with hot food, was washed with hot water or was used to store liquids requires purging. A comprehensive analysis regarding when purging is required and how one determines which form of purging is effective is beyond the scope of this article. I will describe the standard method of purging flavor from the most common items. Utensils made from the following materials cannot be kashered:

As a rule, materials such as fabric, metal, wood, rubber and stone (for example, granite and marble) can be kashered. It is not practical to kasher the following items since they require libun gamur (an intense form of kashering usually requiring a blowtorch).

Specific Items

All methods of kashering noted in this section presuppose that the equipment was thoroughly cleaned, as described above.

Silverware, Pots and Other Small Items

Small items are kashered with hagalah, which involves:

  1. Not using the utensil for anything, including non-chametz, for twenty-four hours. This also applies to the (non-Pesach) pot in which the hagalah water will be boiled.
  2. Submerging the utensil in boiling water that is over the fire. The water must be at a rolling boil before the utensil to be kashered is put into it, and the water must touch every surface of the utensil. Therefore, each item should be kashered individually, and the water should be allowed to return to a boil before the next item is placed into the pot. Large utensils may be submerged in the water one part at a time.
  3. Removing the utensil from the water and rinsing it in cold water.


Kashering a Self-Cleaning Oven:

  1. Remove any large pieces of food (or other items) from the oven.
  2. Go through one complete selfcleaning cycle with the racks in place. It is preferable that the racks be cleaned and remain unused for twenty-four hours before they and the oven are kashered.

Kashering a Non-Self-Cleaning Oven:

  1. Clean walls, floor, door, ceiling and racks thoroughly with an abrasive cleaner (for example, Easy-Off) to remove tangible chametz. Pay special attention to the temperature gauge, the window in the door and the edges of the oven chamber. Black discolorations that are flush with the metal do not have to be removed.
  2. Once the oven is clean, it is preferable that it remain unused for twenty-four hours.
  3. Place the racks back into the oven, and turn the oven to broil for oneand-a-half hours.
  4. Pesach food or pans may be placed directly on the door or racks once the oven has been kashered.

If the oven has a separate broiler chamber, it should be kashered in the same manner as the oven chamber. A broiler pan that comes in direct contact with food cannot be kashered.

Note: The method of kashering described above is based on the ruling of Rav Aharon Kotler. However, Rav Moshe held that the oven must either be kashered with a blowtorch, or an insert must be placed into the oven for the duration of Pesach. Consult your rabbi for guidance.


The grates of a gas stovetop should be kashered in the oven chamber in the same manner described above. For an electric stovetop, just clean the coils and turn on high for ten minutes. If you have a glass-topped stovetop you should consult your rabbi for directions on if/how it can be used for Pesach.

For a gas or electric stove, it is preferable to replace the drip pans that are under the burners; if this isn't possible, the area should be covered with aluminum foil. The work area between the burners should be cleaned and covered with two layers of foil. The knobs and handles of the oven and stovetop should be wiped clean.


Kashering a Stainless Steel Sink:

  1. Remove the filter covering the drain and put it away for Pesach with the chametz dishes.
  2. Clean the sink, faucet and knobs, and don't use the sink for anything other than cold water for twenty-four hours.
  3. Boil water up in one or more large pots (clean pots that have not been used for twenty-four hours). The pots may be chametz pots.
  4. Dry the sink, then pour the boiling water over every spot on the walls and floor of the sink and on the faucet and knobs. One may kasher part of the sink and then boil more water for the rest of the sink. Extreme care should be taken during this type of kashering to ensure that none of the boiling water splashes onto the person doing the kashering or others who are nearby.
  5. Place an uncovered pot of boiling water directly under the faucet so that hot steam will rise and come in contact with the entire underside of the faucet.
  6. Rinse the sink and faucet with cold water.
  7. Put a new filter over the drain. One should also purchase new sponges and a fresh bottle of dishwashing liquid.

Kashering a Porcelain Sink:

Since a porcelain sink cannot be kashered, one should kasher the faucet and knobs as outlined above and, for the duration of Pesach, place a basin (or insert) into the sink. All dishes, silverware, et cetera, should be placed and washed in the basin, and washwater can be disposed of through the sink's drain. One should be careful not to allow the sink to fill with hot water while the basin is in the sink.

Microwave Oven

Where needed, one can use a chametz microwave on Pesach by

  1. Placing a "Pesach plate" on the floor of the microwave and
  2. Double-wrapping the food on all sides before placing it into the microwave. (Be sure that the outside of the wrapping and all sides of the "Pesach plate" are completely dry.) There are halachic questions as to if/how one can kasher a microwave. One could consult with his rabbi.

Refrigerator, Freezer, Food Shelves and Pantry

These areas should be thoroughly cleaned—paying special attention to the edges where crumbs may get trapped— and the shelves should be lined with paper or plastic. The refrigerator and freezer will operate more efficiently if one pokes a few holes in the lining.

Tablecloths, Kitchen Gloves, Aprons and Other Items Made of Fabric

Any item made of fabric can be kashered by washing it in a washing machine set on "hot" and then checking to make sure that no pieces of food remain attached to it. Vinyl and plastic-lined tablecloths cannot be kashered.

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