Author Archives: Lise Stern

Lise Stern

About Lise Stern

Lise Stern is a food writer living in the Boston area.

Kashering Pots & Pans

Reprinted with permission from
How to Keep Kosher

Pots and pans used on the cooktop to heat liquidy food can be kashered by hag’alah [boiling]. Not frying pans, though. For pots and pans not used for frying: Clean them first, wait 24 hours, and then heat a pot of boil­ing water. If the pots are too big to submerge completely in the hag’alah pot of water, use tongs to hold one side of the pot and submerge it partially for about 30 seconds, then turn the pot and continue submerging it, part by part, until the whole pot has been sub­merged.

kashering pots and pans

If the pot is too big to fit into the kashering pot, you’ll make somewhat of a watery mess. Fill the pot to the lip with water and bring to a boil. In the meantime, put a large stone or a brick (cleaned) over another burner so it can heat up. When the water boils, take the hot stone (with tongs!) and drop it into the boiling water. This should cause the water to rise uniformly, spilling over the sides, thereby covering the outside of the pot with boiling water. This is the procedure you can use to create a kashering pot in the first place. You will also need to [again] kasher the kashering pot in this way when you are through doing hag’alah on everything else.

Pressure cookers are similarly kashered through hag’alah, including the rubber gasket. Frying pans that used oil, according to Orthodox ruling, should be kashered by libun kal [“simple purification”]: They should be heated on a burner set over high heat until a piece of paper

touching the pan gets singed.

Note: Pans that are coated with Teflon, according to the Orthodox, cannot be kash­ered; according to Conservative ruling, they can. If the surface is fairly scratched up, which happens with Teflon, the pan should be replaced (as it should be anyway; who knows what’s in those flakes of Teflon that might come off into your scrambled eggs?).

Baking Pans

You will likely need to get a new set of metal baking pans. Metal pans used for baking must be kashered by libun gamur–that is, heated over an open flame (such as a blow­torch) until they are red hot. This treatment can damage many pans, such as those made from aluminum. If you have heavier pans, they may survive red-hot temperatures, but usually people opt to buy new baking pans. You will also need to scrub off any baked-on residue. As with other items to be kashered, clean the pans and let them rest, unused, for 24 hours.

Kashering Utensils

Reprinted with permission from
How to Keep Kosher

Silverware and stainless steelware can be made kosher through hag’alah [boiling]. The day before kashering, clean all the flatware and let it rest, unused, for 24 hours.

Some flatware handles are made of a different material, such as Melmac (a hard plas­tic) or wood. You can submerge the entire piece, if it can withstand the heat. Otherwise, its kasherability is debatable. Some rabbis I spoke with said you can submerge just the metal part of the flatware; since you don’t eat with the handle, it doesn’t matter if it is kasherable or not. Others say the entire implement may not be kashered. Check with your rabbi.

Kashering silverware

It also depends on how smoothly attached the handle is. If it seems loose, if there seem to be cracks or spaces into which food could enter, which would be very difficult to clean, you probably should not use it, and it should be replaced. This is also the case with knives, many of which have handles made of a separate material.

The flatware pieces cannot touch each other, lest those parts touching not be fully ex­posed to the water, so this is a somewhat tedious procedure, especially if you have a lot of silverware. The Star-K organization [which overseas kashrut for food companies] recommends tying the individual implements to­gether in a sort of chain, with a few inches between each piece of flatware, so you can eas­ily lower them into the boiling water.

Another option is a large net bag, as long as it is large enough for the flatware to spread out on the bottom of the pot in a single layer. The flatware should remain in the water about 15 to 30 seconds, and then be rinsed in cold water. Make sure you do not rinse it in an unkosher sink!

The rules for koshering flatware are the same for Orthodox and Conservative fol­lowers.

As for other kinds of utensils, it again depends on the material. There are some made with newer materials, such as spatulas designed to withstand temperatures above 500°F, 600°F, even 700°F. These could certainly withstand hag’alah, but consult with your rabbi, as they are a kind of plastic. Wooden spoons can be kashered by hag’alah.

Kashering Dishes

Reprinted with permission from
How to Keep Kosher

Dishes can be made of several substances: china, earthenware, glass, wood, various plas­tics, metal. Some can be kashered [made kosher], some cannot, some are debatable.

Leviticus 6:21 says, “And the earthenware vessel in which it was cooked shall be bro­ken; and if it was cooked in a brazen vessel, it shall be scoured, and rinsed in water.” This verse is the basis for certain rules of kashering dishes, and what may or may not be kasherable.

Whether or not you can keep the dishes you already own depends on the material from which they are made. If the dishes are “earthen,” that is, china or stoneware, it is most likely you will not be able to keep them, at least not for immediate use. Unglazed earthenware cannot be kashered at all, as the porous ceramic permanently absorbs juices and flavors from foods.


Nowadays, glazed chinaware can be relatively inexpensive, especially compared to 50 or 150 years ago. Consequently, Orthodox and Conservative opin­ions on keeping dishes that were previously used in unkosher kitchens have become stricter. The general opinion is, chinaware cannot be kashered.

Thickly glazed china or fine china, family heirloom material, can sometimes be made kosher, but it must sit, un­used, for at least 12 months; have a rabbi check your china to determine if this rule is applicable. This is the amount of time deemed necessary for dissipation of all unkosher flavors. If the glaze is thin and could easily flake off, the dish likely cannot be kashered. The alternative is to find a kiln and heat the ceramic items at kiln temperatures (about 2,000 degrees Farenheit), but at that heat the china might break.

The rule regarding chinaware applies not only to place settings, but to serving plat­ters, as well as mixing bowls, fruit bowls, and so on. Items that are never used with hot food, such as a ceramic fruit bowl or a sugar bowl, are not treif [unkosher] and don’t need kashering.

Kashering Stoves & Ovens

Kashering–making something kosher–can be difficult, and–because of the liberal use of boiling water, highly heated appliances, and blowtorches–dangerous. In addition to offering advice, many rabbis would be happy come over and assist you in kashering your kitchen. Reprinted with permission from How to Keep Kosher (HarperCollins).  


There are many kinds of cooktops, from standard gas and electric to futuristic radiant heat with a glass-ceramic surface. Gas cooktops generally consist of the pilot burner, a hinged cooktop, metal plates around each burner, and grates, or “spiders,” that rest on those grates. Electric cook-tops are similar, but without the grating, as pots and pans rest directly on the heating coil.

Let the cooktop rest, unused, for 24 hours. Remove all the burner grates and plates and wash thoroughly. Scorn the stovetop. If possible, lift the stovetop and clean underneath. I’ve been amazed at the amount of food that seems to escape into the seamy underside of my gas stovetop. Make sure to clean temperature setting dials as well. Once all the separate parts are cleaned, reassemble your stovetop.

Once the cooktop is cleaned thoroughly and reassembled, turn each burner on high. Check with your rabbi as to the amount of time the burner should remain on. One Orthodox rabbi I spoke with said 15 minutes was sufficient–you want those iron grates or the electric coils to get red hot. According to Conservative tradition, the burners should remain on for 45 minutes. Some Orthodox rabbis say the gas cooktop iron grates may be kashered when you kasher your oven . You can put them in the oven during the self-cleaning process, although you may want to check with the manufacturer that this won’t cause damage.

In order to ensure that the area immediately surrounding the burners is adequately heated and kashered, one Orthodox rabbi I spoke with recommends placing a blech on top of the heating burners. A blech is a metal tin, shaped like an inverted cookie pan [or just a flat sheet of metal], which you place on top of the burners to dissipate the heat if you leave the stove on dur­ing Shabbat. When you see the blech glowing faintly red (most visible with the lights turned off), the burners are kashered (and so is the blech). Alternately, cover the burner areas with heavy-duty aluminum foil or a double layer of regular foil.

Kashering Cabinets, Drawers, & Countertops

The following article describes various opinions regarding the kashering–making kosher-of cabinets, drawers, and countertops. When it comes to deciding which custom to follow, it is advisable, as the author notes, to discuss the matter with a rabbi. Reprinted with permission from How to Keep Kosher (HarperCollins).  

Cabinets & Drawers

Cabinets do not generally hold heated food. Therefore, they can be kashered relatively easily. Kashering basically means cleaning. Remove everything and wash the shelves and the sides. If you use shelf or drawer liners, discard the current ones and replace with new liners. Let them sit, empty, for 24 hours, then put away the food.


Unlike cabinets, countertops do get exposed to heat. For example, if you have a heat-resistant countertop, such as wood or granite, you might put a hot pot directly on it. Or the hot ingredients inside a pot–soup, stew, hot cocoa–might spill onto it.

countertop kitchenThe material that your counter is made of determines whether or not it is kasherable. Regardless of the matetial, you need to clean countertops thoroughly and let them sit, unused, for 24 hours.

Countertops today are made of a myriad of materials. According to Conservative rules, all countertops are kasherable except for those made of tile, since it is earthenware.

Formica & Other “Plastics”

According to some Orthodox rulings, certain types of counters cannot be kashered. Materials that are not kasherable include the very common Formica, quartz and resin amalgamations such as Silestone, and mineral and acrylic polymer composites such as Corian. These all fall under the category of plastic, and plastic, according to some Or­thodox tenets, cannot be kashered. Some do say that Corian can be sanded down and can be kasherable in that way, but opinions vary.

Opinion is mixed as to what “not kasherable” means in terms of how to use that counter in your kosher kitchen. One Orthodox rabbi I spoke with said such counters should be covered, usually with Contact paper. Another Orthodox rabbi I spoke with said while such counters are not kasherable, it doesn’t matter; they do not need to be kashered because of how countertops are used.

Kashering Sinks

Reprinted with permission from
How to Keep Kosher
(HarperCollins).  Sink

The kitchen sink is a hotbed of treif (unkosher). Most likely, before you started thinking about keep­ing kosher, pots, pans, and dishes with traces of milk and meat products went into that sink, and hot water swirled over them, mixing everything together. The hot water can get quite hot, definitely in the yad soledet bo range [meaning “when the hand shrinks back from it” because of the heat–the point at which Jewish law considers a liquid hot].

Enameled porcelain sinks are treated as earthenware, a substance that absorbs flavors permanently. These sinks are not kasherable. Stainless steel sinks can be kashered.

Two Sinks?

The kashrut preference, for both Conservative and Orthodox rules, is to have two separate sinks, one for meat and one for dairy, because a sink can so easily become treif. A double sink is possible, but difficult to keep kosher, as spills from one to the other can happen too easily.

But for many people two separate sinks are not an option. This does not mean you cannot use your sink. If you have only one sink, even if it is stainless, it will quickly become unkosher through normal use. But you should still kasher it when kashering your kitchen.

Making It Kosher

Sinks are kashered through irui [infusion]. Scrub the sink thoroughly. Some Orthodox rabbis encourage pouring a bleach solution down the drain, but this is a mahmir [strict] position, as the drain and garbage disposal will never come in contact with food you actually prepare to eat.

Do not use the sink for 24 hours. Then boil water and pour it all over the sink, including the faucet and the lip of the sink that overlaps onto the counter (don?t for­get to put towels or rags on the floor).

Some sinks have a retractable spray attachment, the nozzle of which is usually plastic. According to some Orthodox rabbis, this is not kasherable and should be replaced or not used. According to Conservative halakhah (Jewish law), it is kasherable–include this nozzle during the irui process.

Kashering (Making Kosher)

Reprinted with permission from
How to Keep Kosher

Kashering your kitchen is at least a two-day process. You will need to clean all the ele­ments and then wait 24 hours before kasher­ing them. This goes back to the rule [known as] eino ben yomo, “not of the day”–a full 24-hour day must pass in order for the various parts of your kitchen to lose any unkosher flavor they might have absorbed.

After 24 hours, those flavors are considered ta’am lifgam, having a bad taste. This minimizes the chance that traces of treif [unkosher food] could still contaminate the kitchen while it is being kashered.

kosher quizAs It Is Absorbed…

The basic rule of kosherizing is k’volo kakh polto, an expression that means, literally, “as it is absorbed, so is it purged.” (Interestingly, the same expression means “easy come, easy go”; not necessarily the case when it comes to kashering.) In other words, the way a potentially kosher item became unkosher determines how you can make it kosher.

There are four methods of kashering. Because a heat source is what caused various items to become unkosher (an oven, a pot, a pan), heat is used to remove unkosher substances from these items. And some items cannot, by nature, be purged.

kasheringThe methods of koshering include the following:

Libun is used for items heated directly on a fire, such as a grill, baking pans used in an oven, or frying pans used to heat oil. The word libun means “purify” and comes from the same Hebrew root word for “white.” There are two types of libun:

1)      Libun Gamur, “complete purification.” When the term libun is used by itself, this is the kind of libun being referred to. Libun means heating a pan or grill until it is red hot. To heat pans until they are red hot usually requires a blowtorch, as your standard oven does not reach temperatures that are hot enough, and this is a procedure most often performed by a rabbi.

2)      Libun Kal, “simple purification.” Heating metal hot enough that paper (traditionally, a broom straw) touching it scorches. When an oven goes through a self-cleaning cy­cle, it gets this hot. This is a method you might use on a frying pan.

Hag’alah, “scouring” or “scalding,” is used for items such as pots or flatware that have become treif through contact with hot liquids. Hag’alah means kashering the item in a large pot of boiling water.

Irui, “infusion,” is kashering by pouring boiling water over something, a method used for countertops and sinks.

Waiting Between Meals

Reprinted with permission from How to Keep Kosher (HarperCollins). 

We’ve established that you cannot eat meat and dairy foods together. This means that a meal is either a meat meal or a dairy meal (or a pareve meal for that matter). You cannot even have meat and dairy at the same table; that is, one person can’t eat a bagel with cream cheese at the same table where someone is eating fried chicken.

To clarify further, you can’t have a piece of steak on one plate, prepared without any dairy, then turn to a second plate and chomp down on a piece of cheese, even if you’ve swallowed the steak.

kosher waiting between meals

To ensure that meat and milk not be eaten together in any way, it is customary to wait a certain amount of time between meals. After eating meat, the wait time varies, but the generally accepted amount of time to wait is six hours.

Different Traditions

Different traditions developed as to the exact amount of time that must pass between meat and dairy meals. Wait time is required because of the nature of meat. In The Laws of Kashrus, Binyomin Forst explains that the sages give two primary reasons: Meat leaves behind a fatty residue in the throat, and particles of meat might remain between your teeth. Time is necessary for the digestive powers of saliva to break down both that fatty residue and the meat particles.

For Orthodox Jews, the most common wait time is six hours. According to Sephardic tradition, six hours is not merely tradition, but halakhah, required by Jewish law. Ashke­nazic tradition says that more lenient options are also halakhically correct. Most agree that the meat meal should be concluded with appropriate blessings, signifying the meal is over. You should then clean and rinse your mouth and wash your hands.

Some say one hour is sufficient time, and this has been the accepted tradition of Dutch Jews. German Jews follow a tradition of waiting three hours. Forst says this may be based on the idea that in winter the time between meals is shorter; therefore, it is acceptable to wait a shorter amount of time year round.