Sinks, Countertops, and Tabletops
Sinks are a special challenge in a kosher home. Most sinks, unless they are made of metal, cannot be kashered. Therefore, rubber or plastic sink liners or basins should always be used when dishes are washed or placed in the sink.
An in-sink garbage disposal unit will often make it practical to consider the sink non-kosher space, thus allowing the use of the disposal unit for meat and dairy food alike.
If a sink is metal, however, it may be kashered by being cleaned thoroughly with appropriate cleansers, including the lip around the edge of the sink where food tends to accumulate and in the seam areas around the drain. Boiling water is then poured over all surfaces and directly into the garbage disposal and drain.
Formica (and similar kinds of countertops) may be kashered by being scoured with appropriate cleansers, paying careful attention to seams. The counter must then be left unused for at least twenty-four hours, whereupon boiling water must be poured over the surfaces.
Raw wood or butcher block surfaces must be sanded to be made usable in a kosher kitchen. Then, after twenty-four hours have passed, boiling water must be poured over the surface.
Tabletops made of fine-finish woods must be cleaned with appropriate wood cleaners and then washed.
It is important to note, however, that the water poured onto the sink or countertop must come directly from the kettle or pot in which the water was boiled.
This procedure is called irui mi-k’li rishon, “pouring [hot water] from the ‘first’ vessel,” the vessel in which the water was first boiled.
Refrigerators and Freezers
To prepare a refrigerator for use in a kosher kitchen, it should be emptied, then washed inside thoroughly with soapy water and rinsed. Wire or glass shelves should be cleaned and rinsed.
Freezers should be defrosted fully and washed thoroughly.
Special care must be taken to clean the ice storage bins in automatic ice makers and to clean out the crumbs from seams and corners.
Dishwashers may be kashered by cleaning them as thoroughly as possible, taking special care to scour the inside area around the drain and the filters. One should then run the machine through a full cycle with detergent, leaving the racks in place but empty of dishes.
After twenty-four hours of not being used, the dishwasher should then again be run (again with nothing but the racks inside), and then dried at the highest heat available.
Ovens and Stoves
To ready a self-cleaning oven for use in a kosher home, the inside must first be wiped free of all visible food particles and drippings. The self-cleaning cycle is then run with the racks still in the oven.
If one follows the manufacturer’s recommendation that racks not be in the oven during the cleaning cycle, one must purchase new racks or use a blowtorch as described below.
To ready a non-self-cleaning oven for use, the inside must first be wiped free of all visible food particles and drippings. An oven cleaner may then be used to clean the oven and the racks.
After being cleaned, the oven must be heated to the highest temperature possible and then left on for thirty minutes. The broiler must be run at full heat with the door closed and the racks in place minimally for fifteen minutes.
Alternatively, one may use a blowtorch to heat all surfaces of the oven and racks until they are hot enough to ignite a piece of tissue on contact. Care must be taken, however, not to singe the gaskets around the door.
To prepare a gas stovetop for use in a kosher home, the underburner bowls must first be scoured thoroughly or replaced.
The area under the cook-top must then be cleaned thoroughly. Finally, each burner must be left burning on its highest setting until the pot grids glow red.
To kasher an electric stove with heating coils, the underburner bowls and drip pans must first be thoroughly scoured or replaced. The area under the cooktop must then be cleaned thoroughly, and each burner must be scoured and then turned on at its highest setting for at least ten minutes.
To kasher an electric stove with a glass top, the top must first be cleaned according to the manufacturer’s directions. Each burner must then be left on its highest setting until the coils are red-hot. Boiling water must then be poured over the surface area.
To kasher a microwave oven, the interior must first be cleaned thoroughly with standard cleaners.
After that, an eight-ounce cup of water must be placed in the oven, which is then run on high until the entire cavity fills with steam. The exact time for this will vary from oven to oven because of differences of size and power, but the usual amount of time needed is roughly three minutes after the water has first come to a boil.
Toasters and Toaster Ovens
It is possible to kasher a toaster, but it will usually make more sense simply to buy a new one.
To kasher a toaster, it must first be fully cleaned of all crumbs and drippings, including on the crumb tray, then run empty for two cycles at its darkest toast setting.
A toaster oven with a broiler, including its racks and crumb tray, may be kashered by being fully cleaned of all crumbs and drippings and scoured with steel wool. The toaster oven should then be run at the broil setting for ten minutes with its rack in place.
A toaster oven without a broiler may be kashered by being cleaned fully of all crumbs and drippings, including those in the crumb tray, its sides, and its door or doors.
The racks must then be cleaned with steel wool, then two empty cycles run at the darkest toast setting followed by fifteen minutes at the highest baking heat with the rack or racks in place.
Mixers, Blenders, Food Processors, and Juicers
As with toasters, it will often be more reasonable to replace the entire mixer.
However, it is possible to kasher appliances like mixers and blenders, which is often undertaken precisely because so many mixer bowls and attachments are needed in a kosher home: one set each for pareve and dairy, and perhaps even a third set for meat.
Multiple sets of accessories for the same brand or model of mixer must be marked clearly. The motor unit of a mixer may be kashered by thoroughly cleaning the body and stand thoroughly, as well as the seams and joints.
As far as bowls, beaters, and whisks go, the easiest alternative is always to purchase new ones. It is possible to kasher them, however.
Glass mixing bowls need to be cleaned thoroughly, ideally in a dishwasher with a heated drying cycle. Metal bowls, including the seam beneath the lip, need to be cleaned thoroughly and then covered with boiling water, either by having the water poured over the bowl or by dipping the bowl in boiling water.
The beaters and whips must be cleaned thoroughly, especially in the seams, then submerged in a pot of boiling water.
Rubber parts must be replaced. Blades and wholly heat-resistant, knick-free plastic parts may be kashered by being submerged in boiling water. Glass containers must be washed carefully, then run through a dishwasher.
Coffee Makers, Can Openers, Slow Cookers, and Knife Racks
Coffee makers may be kashered relatively simply by cleaning the body of the coffee maker thoroughly, then by submerging all washable parts in boiling water either by pouring the water over the parts or by immersing them in a pot of boiling water.
It is easiest to replace can openers.
If one chooses not to do so, a can opener may be kashered by cleaning the cutting head thoroughly—an exceedingly difficult task—and then immersing it in boiling water. Considering the low price, it is best to have separate can openers for dairy, meat, and pareve.
Because they are so useful for Shabbat cooking, slow cookers are very popular in observant Jewish homes.
One-piece units must be replaced. Two-part units, however, can be kashered. New inserts must be purchased. The heating unit itself must be cleaned fully with approved cleaners and may then be used, with different inserts, for different kinds of food. The inserts must be marked as to type.
Because they can generally not be opened, the kind of knife racks into which the knives are inserted cannot be kashered.
A new one should be procured, and its slots marked for meat, dairy, or pareve knives, then used exclusively for that specific kind of knife.
The kind of magnetized rack from which the knives are suspended may be kashered by being cleaned thoroughly, after which its slots must be marked for meat, dairy, or pareve knives.
Broiling Pans and Skewers
Broiling pans and skewers that come into direct contact with fire during use may be kashered either by exposing them to the same heat source or by heating them with a blowtorch until the item glows red or until a tissue flames when touched to the surface.
Adapted with permission from The Observant Life.