Kashering for Pesach by Rabbi Jonathan Muskat

Basic Concepts

  • Among the basic mitzvoth of the holiday of Pesach, we are commanded to rid our home and possessions from hametz. In doing so, we must clean and kasher all kitchen equipment, utensils and articles that are used in our kitchen year round.
  • Cleaning: The goal of cleaning is to remove all tangible traces of hametz. As a practical matter, items which have narrow cracks, crevices or other areas that cannot easily be cleaned cannot be kashered for Pesach. Note that even the smallest amount of hametz is forbidden to eat.
    • Examples include: colanders, baby bottles (narrow necks), filters or screens over drains in sinks, graters, knives where food or dirt can get trapped between the blade & handle, slotted spoons, sponges & toothbrushes.
  • Kashering: The goal of kashering is to remove taste that was absorbed usually through the medium of heat. Ashkenazim rule that on Pesach, even a stale taste of hametz that was absorbed in a utensil is forbidden. Generally, the way taste was absorbed is the way that it is removed – dry heat with dry heat (libun) and liquid heat with liquid heat (hag'ala).
  • As a preliminary note, my positions are based on the assumption that generally we do not kasher glass for Pesach. Some poskim are lenient in this regard; therefore, if you have a personal, difficult situation relating to either a "glass" appliance, please feel free to contact me.


  • Non self-cleaning oven: Clean entire inside of oven with an abrasive cleaner (e.g., Easy-Off) to get rid of tangible hametz, then preferably wait 24 hours and don't use the oven and then turn on the oven to the highest temperature for an hour and a half.
    • Broiler pans: According to Rabbi Herschel Schacter, broiler pans that come in direct contact with the food also may be kashered using the same method even if they come in direct contact with the food.
  • Self-cleaning oven: Remove any visible pieces of food from the oven and go through the complete self-cleaning cycle with racks in place.


  • Gas stovetops: Grates of a gas stovetop should be kashered in the oven when the oven is being kashered as is discussed above.
  • Electric stovetops: Clean the coils or surface & turn on high for 10 minutes.
  • The cooktop surface (& ideally the knobs and drip pans) should be cleaned & covered for Pesach.
  • Many glass stovetops may break if they are covered; therefore, the only way to use these stovetops for Pesach is if one replaces the glass, if it is possible. If this is not possible, then one should not use an electric stove with a glass stovetop on Pesach.
    • Examples of glass include: corningware, corelle, fiberglass, porcelain enamel, pyrex or thermoses


  • One may kasher a dishwasher whose inside surface is metal or plastic, even without the need for new racks.
  • To kasher the dishwasher, one should clean out the filter, wait 24 hours & run it on the hottest cycle with dishwasher detergent.


  • One may kasher a microwave whose inside surface is metal or plastic.
  • To kasher the microwave, one should clean the microwave and then preferably wait 24 hours and not use the microwave. Then one should place a cup of boiling hot water until the water begins to evaporate; additionally, one should replace the plate on the bottom of the microwave.

Warming Drawer

  • One may light a few cans of the type of canned fuel used to heat chafing dishes (e.g., Sterno cans) in the warming drawer. Leave the door of the warming drawer slightly ajar, so that there will be enough air to allow for combustion. 2-3 of the 7-8 ounce sized cans should be adequate to heat an average sized warming drawer for about 2 hours. Before koshering, the warming drawer must be thoroughly cleaned & not used for 24 hours.


  • Metal:
    • Clean the sink, faucet & knobs & don't use the sink for anything other than cold water for 24 hours.
    • Boil water in one or more large pots that have not been used in 24 hours.
    • Dry the sink, and then pour boiling water over every spot on the sink & on the faucet.
    • Replace or clean the filter (depending on how fine the filter holes are) & get new sponges & dishwashing liquid.
  • Porcelain:
    • Kasher the faucet & knobs with boiling water & place a basin or insert into the sink & rack underneath the basin & all dishes & silverware should be washed in the basin & don't fill the sink with boiling hot water.

Counter tops

  • Granite, marble, wood, stainless steel, corian, plastic and formica countertops can be kashered like a stainless steel sink.
  • One may also kasher these countertops with a power steamer that sprays steam which becomes condensate, provided that the condensate is applied to every spot of the countertop.  The Wagner Power Steamer 905 can be used in this regard.
  • Clean and then cover ceramic & porcelain countertops, as they are considered pottery which cannot be kashered.
  • Even in kasherable countertops, one should not kasher them if there are deep scratches or cracks in the countertop, out of concern for tangible hametz.

Kitchen cabinets & refrigerators

  • Kitchen cabinet and refrigerator shelves must be cleaned well. Some have the custom of lining the shelves, but this is not absolutely required.


  • The following vessels may be kashered through hag’ala, or purging: metal, stone, plastic and wood (provided that there aren’t large cracks in the wood which may contain real food pieces). Glass, pyrex, duralex, corelle, crystal, corningware, porcelain and china should not be kashered.
  • The hag'ala process is as follows:
    1. Clean the utensil to be kashered & let it remain unused for 24 hours.
    2. Place the utensil in a pot of rapidly boiling water (large bubbles – not just steam). Any pot (dairy or meat) that has not been used in 24 hours may be used for this purpose.
    3. A pot that is too large to fit into another pot for the purposes of kashering may be kashered by filling up the pot with boiling hot water and placing a boiling hot rock in the water so that the water will spill over the all of the edges of the pot. The pot may also be kashered part by part, by purging it in the water one side at a time, but one must make sure that each part of the pot is completely surrounded by water at some time during the hag’ala process.
  • Kiddush cups or drinking glasses may be kashered by hag'ala or by filling them up with water for 24 hours, emptying and then refilling them for another 24 hours, etc., for a total of 72 hours. Note, however, that it is recommended to get separate whiskey drinking glasses for Pesach because of the sharp taste remaining in these glasses.