Since this year it is impossible to make use of a central, public kashering of utensils or have our kitchen kashered by others, we must do it ourselves * In order to do so, one must learn what is halachically necessary, without chumrot and hidurim difficult to perform in the house * Guidelines for kashering the oven, pots, cutlery, and other kitchenware according to halakha, by household means
The General Rule of Kashering: Ke-Bole’o Kakh Polto
This year we will not be able to make use of a central kashering to perform libun of stovetop grates, and hagala of pots. There are also people who usually have others help them kasher their kitchen for Pesach, and this year they will have kasher it themselves. Therefore, it is necessary to study the halakhot of kashering the kitchen and utensils for Pesach as required by halakha, without chumrot and hidurim that are difficult to do at home. The references to “Peninei Halakha – Pesach” are for the new edition of 5780  (found on the website of ‘Yeshiva Har Bracha’, and can be downloaded in the app). Let us begin clarifying the general rules.
The basic rule in the laws of kashering utensils is “ke-bole’o kakh polto” (a forbidden taste is released from the utensil in the same manner that it was absorbed). That is, the utensil should be kashered in the way it was used b’issur (in a forbidden manner) or with chametz. There are three forms of use: 1) with fire, whose kashering is done by heavy libun (heating the vessel by fire until it gives off sparks or becomes red hot). 2) With hot liquids – whose kashering is done by hagala in boiling water. This, too, has different levels: the use of a kli rishon (the vessel in which the food is cooked) on a flame, a kli rishon removed from the flame, liquid poured (irui) from a kli rishon, kli sheni (hot food that was first cooked in a vessel over fire and then transferred to a different one), and ke-bole’o kakh polto. 3) With liquids that are not hot, in which case it is enough to clean them in cold water to kasher them.
A Utensil Used on Two Levels
A spoon that sometimes absorbed chametz in a kli rishon on a flame and sometimes in a kli sheni is kashered according to its most intense absorption, namely, in boiling water on a flame. However, when this is difficult or can cause damage, we go according to its usual use. For example, a fork that is usually used in a kli rishon or sheni whose kashering is done in boiling water, but sometimes the fork is stuck in a baked good while in the oven where its absorption is with fire – since libun is liable to damage the fork, we go according to ikar ha’din (strict law), and the fork is kashered according to it predominant use, in boiling water (Peninei Halakha: Pesach 10:7).
Cleaning the Kitchen and the House
There is a huge difference between cleaning the house for Pesach and cleaning the kitchen. In cleaning the house, the goal is not to leave a crumb of chametz the size of a ke’zayit (olive), in order not to transgress the prohibition bal yera’eh (“no chametz of yours shall be seen”) and bal yimatzei (“no se’or of yours shall be seen within all your borders”) [Shemot 13:7], whereas in the cleaning of the kitchen and its utensils, the goal is not to leave even kol she’hu (the slightest amount) of chametz, lest it get mixed into Pesach foods. And as known, chametz on Pesach is forbidden even kol she’hu. And when it comes to utensils used to cook with, one must make sure there are no remains of the taste of chametz absorbed in utensils, or any residual chametz stuck to them.
Countertop and Sink
Thoroughly clean the marble countertop and the sink, and then pour boiling water on them. It is convenient to do this with a kumkum (kettle). Before pouring boiling water on a sink or countertop, it must be dried well, so that the boiling water touches it directly and is not cooled by any cold water on its surface. For this reason, one must first pour the boiling water on the sink and then on the countertop, starting with the areas closest to the sink and moving further away, so that the water will flow to the sink rather than the places that have not yet been kashered. Instead of pouring boiling water on them, the marble countertop can be covered with linoleum or aluminum foil and a plastic basin placed in the sink, or covered with thick aluminum foil. Those who are stringent do both – they pour boiling water on the countertop and sink, and then cover them with linoleum or thick aluminum foil (Peninei Halakha: Pesach 11: 1).
Fragile marble countertops, on which boiling pots are never placed, le’chatchila (from the outset) can be kashered by merely cleaning and pouring boiling water on them, and even the mehadrim (those who go a step further) need not cover it with linoleum or aluminum foil.
Kashering Grates, Burners, and Stovetops
Throughout the year, people usually use the same stovetop grates for both meat and milk, because even if some meat or dairy food spills onto them, the flame incinerates and befouls whatever has spilled. However, people customarily perform light libun on such grates for Pesach, because of the severity of the chametz prohibition. In ordinary years, many people are mehadrim, and do this by means of burners supplied at public kashering stations, but this year the kashering may be done by cleaning the grate, returning it to its place, and turning on all the flames for about fifteen minutes. Those who wish to go a step further, wrap aluminum foil around the bars on which pots sit. Be’di’avad (a level of performance that ex post facto satisfies an obligation in a less-than-ideal manner), if the grates did not undergo libun, the foods cooked on them on Pesach are kosher (as is customary all year round for meat and milk). The areas of the grates that do not come into contact with the pots, the enamel cook top beneath the grates, and the burners must be cleaned well of all residual food (Peninei Halakha: Pesach 11: 2).
Electric Ranges and Ceramic Burners
Electric ranges and ceramic burners should be thoroughly cleaned, and run on the highest setting for about fifteen minutes.
Kashering a Baking Oven
To kasher an oven, clean it thoroughly and run it at its highest setting for half an hour.
Le’chatchila, we go according to the machmirim (stringent poskim) and do not kasher baking trays, because in their opinion, libun must be done at a temperature of about 400 degrees Celsius, and in such heat, the trays are liable to warp and have their appearance damaged. Therefore, those who do not have special Pesach trays may use disposable oven trays, and kasher the racks along with the oven, in order to place upon them the disposable oven trays (ibid. 11:3).
In extenuating circumstances the oven trays can be kashered for Pesach by heating the oven for half an hour, relying on those poskim who are of the opinion that utensils do not need to undergo libun at 400 degrees Celsius, rather, it is enough to do libun with the heat they have been used with (Peninei Halakha: Pesach 11:5).
Ovens that self-clean at a temperature of 500ºC need not be cleaned before kashering because such intense heat is considered heavy libun and is sufficient to kasher the oven for Pesach.
The body of the barbecue and its rack should be kashered as it is used, which is a level of heavy libun. If it is a gas barbeque – do so on the highest level of heat, or if used with coals – the largest amount of coals normally used.
There are three steps to kasher a microwave oven: 1) cleaning it thoroughly of any residual food resulting from spillage or vaporization; 2) in order to kasher it from vapors and moisture of chametz in a manner of ke-bole’o kakh polto – heat a container of water in the microwave for approximately ten minutes (since microwave ovens absorb chametz via vapor that rises from food as it is heated); 3) Since chametz may have spilled onto the plate of the microwave, the plate should be cleaned and immersed in boiling water, or by placing something as a separation between the plate and the food that will be heated in the microwave on Pesach. (Peninei Halakha: Pesach 11: 5).
The filter, where residual food often gets stuck, must be cleaned thoroughly. Then the dishwasher should be run at its hottest setting, so that any absorbed chametz is released, ke-bole’o kakh polto, and in this way, it is kashered (Peninei Halakha: Pesach 11: 5).
The Dining Table
Our tables are sensitive and people usually don’t place hot pastries or boiling pots on them, therefore kashering is done by thoroughly cleaning them with a damp cloth, according to it predominant use. Since occasionally a hot chametz sauce splashes on a table, and sometimes a hot pastry is placed on it, it is correct to be careful not to eat it on a table without a tablecloth that will separate between the table and the food.
There are mehadrim who tape a nylon or paper covering on the table, fearing that the tablecloth placed on the table will slip off, and by taping them create a permanent buffer upon which the tablecloth is spread. If this is a table on which dough is occasionally kneaded, a permanent separation must be taped or placed on it.
A table on which no hot chametz foods were placed throughout the year and dough was not kneaded upon it, it is enough to clean it well, and there is no need to cover it (ibid. 11:6).
Since refrigerators are used with cold food, the only concern is that some chametz crumbs might remain there. Therefore, their kashering is done by cleaning. In hard to reach places where chametz crumbs may have gotten stuck, one must pour soapy water or some other substance that will befoul the crumbs and render them unfit for animal consumption.
When kitchen cupboards were made of natural wood, they often had cracks and crevices that were difficult to clean completely of chametz that got stuck there, thus, the custom was to line them with paper. However, in smooth shelves like those used today, there is no concern that chametz remains. Therefore, once they have been cleaned properly, they need not be covered.
In these days when pots and cutlery cannot be kashered in public hagalat kelim, which are needed to kasher chametz utensils for Pesach that have been used with a kli rishon on the fire, the kashering must be done at home.
To do this, take a large clean pot, whether it be a chametz pot, or a Pesach pot. Boil water in it, place in the water a bit of liquid soap to damage its taste, and any utensil one wishes to kasher – is placed in the boiling water for about three seconds.
Le’chatchila, the custom is to rinse the utensils in cold water immediately after hagala, but if for some reason it is difficult to rinse a utensil with cold water, one need not make an effort to do so.
If a utensil cannot be immersed in its entirety into the water, it can be immersed one half at a time (ibid. 10: 11).
The hagala of a pot should be done in a large vessel in which all of the pot can be inserted. It is not enough to boil water in the pot, because most likely during the year food over-flowed or splashed on the rim of the pot, and consequently, the taste of chametz is absorbed and stuck to the upper lip of the pot, and the pot rim is not kashered by the boiling water inside the pot.
When the handles of the pots can be disassembled, there are mehadrim who take them apart and clean them. Instead of this, one can clean around them with a lot of soap, until it is clear the taste that may be in the grooves is nifgam (fouled), and then, immerse the pot. Pots with metal folding edges do not need special care.
If one cannot find a vat large enough to immerse the pot, boil water in a small vessel, and when the water in the large vessel begins to boil, insert the small vessel into the center of the larger vessel. This will cause the water in the larger vessel to overflow and kasher its rim and outer walls. It is also possible to boil water in a kumkum at the same time, and when the water inside the pot starts to boil, pour the boiling water from the kumkum into the pot, so that the boiling water in the pot will spill over and kasher its rim. The lid of the pot should be rotated in the boiling water, forward and back, until each portion of it is in the boiling water. In addition, the pot handles should be cleaned thoroughly with soap, and boiling water poured on them (ibid. 11: 12; 10: 9).
Clean well and kasher it with light libun, by heating it on the gas fire in the same heat as it is used when frying (ibid. 10: 4-5).
Many Sephardim follow the lenient opinion that glass utensils may be kashered simply by rinsing them thoroughly, whereas many Ashkenazic Jews do not kasher glass utensils for Pesach. In practice, however, the ikar seems to be the middle opinion, which maintains that glass utensils have the same status as metal utensils, whose kashering is done by immersing them in boiling water. Those whose families’ minhag is to be lenient, are permitted to continue in their minhag. And those whose families’ minhag is to be stringent, it is appropriate for them to continue in their minhag (ibid. 11:12).
Warming Tray (Shabbat Plata): Clean thoroughly, heat on highest setting for one hour, and those who act stringently, also cover it with aluminum foil to separate between it and Pesach pots (ibid. 11: 4).
Electric Water Heaters for Shabbat and Kumkum: The custom is to do hagala because chametz crumbs may have fallen into them. Hagala in this case means filling the device to the top with water, boiling it, and then pouring it out through the faucet or opening used to dispense the water. Before hagala, it is good to clean out the stone deposits that accumulated inside. If one puts challah loaves on the lid of the urn to warm them before the Shabbat meal, the lid should be immersed in boiling water.
Coffee Machine: Clean and heat the machine as usual with hot water on the highest heat.
Silver Goblets: It is customary to perform hagala on silver goblets used for kiddush wine and other hard drinks, because crumbs sometimes fall into the goblet along with these strong drinks, which, according to some poskim, causes their taste to be absorbed into the goblet. Since this is a remote concern, when necessary, it is enough to wash them according their predominant use.
Plastic Baby Bottle and Pacifier: It is better to replace them, but when necessary, they may be kashered by cleaning and pouring boiling water on them.
False Teeth: These should be cleaned thoroughly before the onset of the chametz prohibition. They need not undergo hagala, because people do not normally put boiling foods or liquids in their mouths; just as they are used for both meat and dairy when cleaned in between, they may also be used on Pesach.
This article appears in the ‘Besheva’ newspaper and was translated from Hebrew.