Hagalas Kailim - Kashering Vessels

by Rabbi Moshe Lazarus
Reviewed by Rav Yonason Wiener
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This article is part of The Complete Pesach Primer

The following is a summary of the laws pertaining to cleaning the house or apartment for Pesach and the use of utensils used for chometz.As previously mentioned any place in the house where chometz was brought requires a search.This includes:the refrigerator, drawers, closets, books, clothes, pockets, etc.

What To Do With Chometz Dishes

  1. Pots and dishes used for chometz should not be sold with the chometz on Pesach as not to require their immersion in a mikveh after Pesach.
  2. All that is needed is for them to be washed well and put away in a hidden place or locked closet until after Pesach.They need not be kashered.
  3. Chometz she’avar alav HaPesach applies only to actual chometz, not taste.
  4. If a chometz vessel is found on Pesach, it may be cleaned and put away.

Types of Kashering

  1. “Iruiy”– pouring boiling water from a vessel over a utensil.
  2. “Hagala” – Immersion in boiling water.
  3. “Libun Kal” – heating to point that a piece of straw would burst into flame if touched to it.
  4. “Libun Gomur” – heating to red-hot. (Blow-torch, etc.)

Why Vessels Need to be Kashered

  1. Ta’am (taste) is considered as the thing itself.Therefore, if the taste of a forbidden object (or food) is absorbed in the walls of a vessel when the vessel is used again the taste may go into the food.Therefore, if you cooked meat in a new pot and then cooked milk in the pot, the milk is not kosher because the taste of meat absorbed by the pot is now introduced into the milk.
  2. Taste in a pot more than 24 hours is called “notain ta’am lifgam” and does not render the food unkosher b’dieved.The pot, however, is still traif.
  3. There are two ways taste becomes transferred: through heat and through contact with sharp (spicy) foods (i.e. onions, garlic, etc.)
  4. An object soaked in water over 24 hours is called pickling (“Kavoosh”) and is considered as cooked.
  5. “Keboloy Poltoy” (Avodah Zorah 75b) – Taste is removed from the vessel the same way it is put in.Therefore, pots used in cooking need hagala and those used directly on fire (roasting without water) need libun.

Pots And Dishes

  1. The only way to kasher earthenware vessels is to reheat in kiln.
  2. Anything that needs libun or hagala may not be used on a consistent basis without kashering, even for cold.
  3. If the pot is metal or wood, it can be kashered through hagala. Regarding plastic, a rov should be consulted
  4. Ceramic, china, melmac or porcelain utensils are considered earthenware.
  5. To kasher a pot (other than earthenware) that was used on the stove for cooking:
    1. Immerse the pot in a larger pot of boiling water.This will momentarily lower the temperature.Therefore leave it in long enough so that the water continues boiling.
    2. Immediately after immersing the item to be kashered in boiling water, it must be immersed in a container of cold water.
  6. Before immersing, a pot must be cleaned perfectly.
  7. Vessels with handles glued on cannot be kashered.
  8. Pots with cracks may be kashered through hagala only if the cracks are burned out through libun first.
  9. If a handle wasn’t kashered the food is permitted, b’dieved.
  10. All rust must be removed.
  11. Discolorations do not interfere with hagala.
  12. Covers of pots must be kashered if they are not, food cooked in a pot covered by them is prohibited even b’dieved.
  13. Normal “Issurim” (“prohibitions,” i.e. traif) cannot be kashered within 24 hours of use unless libun is performed.
  14. On Erev Pesach, since chometz is still permitted, even within 24 hours of use a pot may be kashered.
  15. The difference between other prohibitions and chometz is, that if the chometz is kashered before the end of the 4th hour Erev Pesach, we are removing a permitted taste and therefore we are lenient.

Frying Pans And Dishes

  1. Frying pans must be thoroughly cleaned.They should be kashered through libun kal, however, b’dieved they are permitted even through hagala b’kli rishon.
  2. Metal or wooden dishes which are used by pouring (iruiy) out from a k’li shaini (a vessel poured into from one which is on the fire) then the kashering is by pouring boiling water from a k’li shaini.
  3. When kashering through pouring it is essential that the stream of water is uninterrupted.


  1. Forks, spoons, etc., should be immersed in a pot of boiling water.The pot should not be used for 24 hours before kashering.This is the rule for kashering other prohibitions.For kashering chometz, if it is done before the fifth hour of the day he need not wait 24 hours.
  2. Knives that were used with heat require libun for other prohibitions.However, for Pesach we are lenient and require only hagala.
  3. Most authorities hold that a knife with a 2-piece handle cannot be kashered through hagala.
  4. When doing libun, rust need not be removed.
  5. Normally we prohibit kashering dairy cutlery or pots in order to be used for meat and vice versa.However, if it was kashered for Pesach it is permitted to make the change.


  1. There are two basic opinions concerning the kashering of glassware:
    1. That glass does not absorb taste and needs no kashering.
    2. That glass does absorb taste and cannot be kashered.

    Ashkenazim hold like the second opinion, regarding Pesach, but are lenient for year-round purposes.
  2. Glass vessels used for cold only need to be washed well.
  3. Glassware used for hot should not be used or kashered for Pesach.
  4. If one cannot obtain new glassware for Pesach, one may kasher through “iruiy gimel yamim.”This means, fill the glass with water and leave it for three 24-hour periods, changing the water every 24 hours.

Refrigerator, Stove & Oven

  1. The refrigerator should be washed out well.If the shelves came in contact with hot food they should be lined with aluminum foil or paper.
  2. Stove tops must be thoroughly cleaned.Tops should be lifted and the entire cooking area cleaned.The area at the base of the burners where the gas is connected usually contains residue of spills and must be cleaned.
  3. The metal grating of the burner must be cleaned and then placed upside down over the lit burners for 15 min. Instead, one can place the shabbos blech over the lit burners for 15 min.
  4. The oven must be cleaned of all chometz.The best tools are commercial oven cleaners and razor blades.
  5. The inside should be burned out with a blowtorch raising the temperature to red-hot level on every spot!(This is extremely difficult to do).
  6. Some authorities allow the oven to be left on its highest temperature for two hours.If this method is used, it is advisable to buy a tin insert that fits into the oven.
  7. Some people prefer not to use the oven and use such an insert (which in any case is covered on 6 sides, one being a door) on top of the stove.
  8. If the oven is not to be used on Pesach it must be cleaned thoroughly of any edible chametz inside and needs nothing more.
  9. Knobs and racks must also be thoroughly cleaned.

Tables & Other Utensils

  1. Table tops should be well covered after they have been cleaned thoroughly.
  2. It is advisable to use a thick covering.
  3. Counter tops or tables on which hot, viscous food is placed should be kashered by pouring boiling water on them and covering with something for use on Pesach.
  4. If it is improbable that it came in contact with chometz it only requires hagala, l’chatchila.
  5. Sinks made of enamel or porcelain should be cleaned thoroughly and have boiling water poured into them and on their sides. Then they should be covered with an insert. Stainless steel sinks can be koshered if they are cleaned thoroughly and not used for 24 hours. Then pour a kettle of boiling water into them so that the water touches each surface of the sink.


  1. The M’chaber says we kasher a vessel in the way that it was used most of the time.
  2. The Rama says we must use the stronger type even if used only once.We hold l’chatchila like the Rama and b’dieved like the M’chaber.
  3. There is no fear that newly bought vessels have been used for chometz.They need not be kashered for Pesach.
  4. L’chatchila one should not even use a k’li shaini on Pesach without hagala.However, if he did, because there is an opinion that taste is not absorbed in a k’li shaini, the food is permitted, b’dieved, if the following three conditions are met:
    1. The vessel wasn’t used in 24 hours.
    2. Considerable financial loss is at stake.
    3. Enjoyment on Yom Tov will be ruined otherwise.
  5. If one may have used a vessel directly on fire, without liquid, it needs libun kal.

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