Utensils used during the year cannot be used on Pesah unless they are first kashered properly.  This is because the hametz becomes absorbed into the utensils, rendering it forbidden on Pesah.  Utensils are “kashered” (made permissible for Pesah use) when they are “cleansed” from the hametz in the same way that the hametz was absorbed, i.e., if the hametz was absorbed through the medium of direct fire, then it is kashered by fire and if it was absorbed through the medium of hot water, then it is kashered with water. These laws are very complex and careful attention must be paid to all the details, as a mistake in these laws can be as severe as eating hametz on Pesah. All utensils which are not kashered should be put away in a closed room or closet which is locked or taped so as not to be used inadvertently. Below are listed the different methods by which utensils are kashered:

Method A – Libun
A utensil that was used over a direct fire must be kashered over a direct fire (i.e., skewers, spits and grills).  The utensil is placed over a flame until sparks are emitted or the utensil becomes red.   This process can be done even if the utensil was used within twentyfour hours.  The utensil does not have to be cleaned thoroughly prior to this process. (Only applies to the Libun method.) Only Libun kashers this type of utensils, but Hagalah does not.

Method B – Hagalah
Utensils (not pottery) in which hametz was absorbed by means of hot water or any other hot liquids through cooking or boiling (not baking) are kashered in boiling water (i.e., pots and pans). Before beginning the hagalah process any dents or small holes must be thoroughly cleansed.  (This also applies to the pot that the hagalah is being done in.)Any rust must be removed from the utensils (discoloration is not a problem).  Since hametz can be found between the pot and the handles, the handles must be removed and that area should also be cleaned.  Not only does the pot need hagalah but also the covers of the pots and the handles need hagalah. The utensil is then placed in a pot of rapidly boiling water for a few seconds.  The water must be continuously boiling. It is preferable not to allow any hot hametz to be in contact with the pot, which is used for the boiling water, for twenty-four hours prior to the hagalah process, as well as the utensil, which is being kashered.  (It is not necessary to kasher the utensils in a kosher for Pesah pot.) However, if the hagalah process is being done on Erev Pesah past the time that hametz cannot be eaten, then it is obligatory that the utensil should not have been used for twenty-four hours. If one cannot immerse the whole pot at once, he may do half at a time. One should not kasher milk and meat dishes at the same time unless one of them was not used for twenty-four hours for hot food. In a situation where the pot was used within twenty-four hours, then the hagalah process can be done by putting soap in the water.

Method C – Irui
A utensil which absorbed hametz through Irui, meaning that the hametz was absorbed by pouring hot hametz that was cooked on the fire onto it, like stainless steel platters (not pottery), sinks, counters, table tops etc., these things are kashered by pouring boiling water onto them.

Method D – Kavush
A utensil which had hametz soaking in it for over twenty-four hours (i.e., beer bottles) is kashered by filling the utensil (until the top) with water.  After leaving it for a consecutive twenty-four hour period, it must be emptied out, and then refilled.  This process must be repeated a total of three times, and each twenty-four hour period must be complete.  If the utensil was soaked for seventy-two consecutive hours without being emptied out after each twenty-four hour period, it is as though it was soaked for only twenty-four hours.

Method E –Tzonen
A utensil which was used only for hametz which was cold and not used for hot (i.e., kiddush cup) needs only to be rinsed out well and may be used for Pesah.   However, it is more preferable to buy new.

Earthenware 
Utensils made of china, porcelain, Corelle or ceramic which absorbed hot hametz cannot be kashered and must be locked away for Pesah in a place where they will not be mistakenly used.

Glass
Utensils made of glass do not absorb hametz and therefore do not have to be kashered for Pesah.  Therefore, washing them well is sufficient. (Sephardic law)