Going Kosher – Preparing for Koshering – Chapter 4

By: Rabbi Amiram Markel


Setting Up Your Kosher Kitchen

 The very first step to living a kosher lifestyle takes place in the kitchen. In an ideal situation, such as a new home in which the kitchen has been built according to kosher specifications; there would be separate meat and dairy countertops, including cabinets and sinks on opposite sides of the kitchen. The sinks would be made of stainless steel which is easily koshered and the countertops would likewise be made either of stainless steel or granite which also is easily koshered.

The dairy cabinets would be situated on the dairy side of the kitchen and the meat cabinets would be on the meat side. There would be a dairy stove, oven, microwave oven, dishwasher and refrigerator on the dairy side and a meat stove, oven, microwave oven, dishwasher and refrigerator on the meat side. The interiors of both dishwashers would be made of stainless steel so that if they accidentally became non-kosher they could easily be koshered. In effect, it would be as if there were two kitchens separated by an imaginary line. Everything would be brand new, including all the pots, pans, cooking utensils, dishes and cutlery. All that would be necessary is to immerse the pots, pans, utensils, dishes and cutlery in a mikvah (Ritual pool), and the kitchen would be ready to go.

Even more ideal would be to have an additional separate Passover kitchen built in. This would be in a completely separate room in the house and would be locked and out of use except for Passover preparations and on Passover itself. During Passover all food would be cooked exclusively in this special kitchen and the regular kitchen would be locked up and inaccessible. It also would be fully equipped with two sets of stainless steel sinks, countertops, stoves, ovens, refrigerators, dishwashers and cabinets; one side for meat and the other for dairy.

However, since this scenario is not possible for most of us, different measures must be taken to assure the kosher status of our kitchen. Your kitchen may not possess many of these ideals. It may only have one sink made of porcelain, one countertop made of tiles or Formica, one stove and oven unit, one microwave oven, one refrigerator and no dishwasher. If it has a dishwasher, it may be the standard home model made with a plastic, enamel or porcelain interior. Moreover, if you are committing to a kosher lifestyle just now, all the equipment has probably been used for non-kosher food, as well as all the pots, pans, cooking utensils, dishes and cutlery. How do we kosher such a kitchen?

Seeking Expert Assistance

The very first step is to call your local orthodox rabbi, synagogue or Jewish organization and ask them for assistance. Though most synagogues would be overjoyed to learn that you are interested in going kosher and would be happy to assist you as much as possible, they may not have the adequate manpower to do so. However, there are many Jewish organizations which perform this service on a regular basis and would be thrilled to help you in every possible way. If the synagogue you contact cannot assist you, they may refer you to an organization in your community that can.

Once you contact them, they will most likely make an initial visitation to your home to inspect your kitchen and to evaluate what procedures would be necessary to kosher it. They will advise you as to how to proceed in preparing the kitchen for koshering. They will explain which equipment and utensils may be koshered and which will need to be replaced, which may be cleaned in preparation for koshering and which must be discarded etc. Later, once you are ready, they will return to help you with the actual koshering process itself.

However, if you live in a remote area or simply cannot find anyone to assist you, abide by the following rules and instructions and, with G-d’s help, you will successfully kosher your kitchen.

Assess What May be Koshered

The basic principle to keep in mind is that any utensil or piece of equipment which has absorbed non-kosher flavor needs to be koshered before use.[1] Absorption generally occurs through heat. However, it may also occur through soaking a non-kosher substance in them for a period of twenty-four hours[2] or through cutting sharp foods, such as garlic, onion, radish, horseradish, chili peppers, lemon or very spicy or sour pickled items[3] etc. even if they are not hot. If a utensil was used with hot non-kosher meat or dairy, we assume that it has absorbed some of it into its walls. It, therefore, must be koshered. Even if the meat and dairy were kosher but were cooked together, we assume that the equipment absorbed some of the forbidden admixture and it must be koshered. In a non-kosher kitchen, such as the one in our scenario, it must be assumed that all the equipment and utensils have absorbed non-kosher substance and must be koshered.

Step One

The very first step in koshering your kitchen is to assess what may or may not be koshered and to separate the unkosherable items from the rest. These items will need to be replaced by acquiring new ones.

1) Generally, anything made of metal;[4] such as steel, iron, copper, bronze, silver, gold, pewter or aluminum[5] etc. may be koshered.

2) Vessels made of solid stone may be koshered.[6] However, there are varying opinions as to whether pulverized stone that has been reconstituted and pressed into vessels or countertops may be koshered or not.[7] This being the case, if possible, it is best not to kosher pulverized stone. However, if this would entail a large monetary expenditure, such as changing a pulverized countertop for a solid granite one, a rabbinical authority should be consulted for a Halachic ruling.

3) Wooden vessels may be koshered on condition that their surface is smooth and that there are no dents grooves or cracks in the wood.[8] If they do have dents, grooves or cracks they should be sanded down to the virgin wood.

4) There is controversy as to whether metal vessels overlaid with enamel may be koshered or not.[9] Most authorities rule that they are kosherable. However, it is best to be strict in this regard and to immerse them in boiling water three times, rather than once, as is regularly done.[10] Ask your rabbi for his opinion. (The various methods of koshering vessels and how they are applied will be explained later.)

5)  Vessels made of earthenware, china or porcelain cannot be koshered.[11] However, if high quality[12] china or porcelain has been unused for a period of twelve months or more, it could possibly be koshered[13] by immersing it in boiling water three times.[14] However, a rabbinical authority should be consulted beforehand for a Halachic ruling.

6)  There is controversy amongst the Halachic authorities regarding the status of glassware. Some are of the opinion that it is similar to earthenware and cannot be koshered.[15] The view of others is that under special circumstances[16] it may be koshered.[17] Still others say that since glassware is nonporous it does not need to be koshered altogether.[18] According to them, all that is necessary is a thorough cleansing, after which the glass may be used.

In practice, the custom amongst Sephardic Jews is merely to thoroughly cleanse the glassware.[19] On the other hand, as a general rule Ashkenazic Jews do not kosher glassware. However, according to many, under certain circumstances,[20] if the glassware was used with cold food or liquid, it may be koshered by immersion in cold water for three days, making sure to change the water after every 24 hour period. The three days need not be consecutive.[21] If it was used with hot food or liquid, it should generally be koshered by immersion in boiling water, as will be explained later. However, this is only if it will not shatter from the heat. If there is any fear that it will shatter, it should not be koshered.[22] This is because, out of fear of shattering them, a person may come to not immersing them properly during the koshering process. Consult your rabbi before proceeding.

7)  Likewise, there is controversy as to whether Pyrex may be koshered or not.[23] A rabbinic authority should be consulted for a ruling.

8)  The prevalent custom is not to kosher plastic. However, according to some authorities, vessels made of hard rubber or plastic may be koshered on condition that they will not melt or be ruined by immersion in boiling water.[24] However, even according to this opinion, since plastic items are usually rather inexpensive and may be difficult to thoroughly cleanse, it may be advisable to purchase new ones, especially in regard to Passover.[25] Consult your rabbi for his opinion.

9) Teflon pans are generally not koshered. Even if they would be it could be problematic. Pans used with little or no oil would need to be heated to extreme temperatures[26]. Those used with substantial oil or liquid would need lesser, but very high heat nonetheless[27]. Therefore, for fear of destroying the Teflon one may come to not applying the correct level of heat. This being the case, it is recommended that they not be koshered.[28] However, according to some, even if the Teflon is destroyed, the pans still retain their utilitarian value as regular pans and may, therefore, be koshered.[29] Consult your rabbi.

Step Two

A further separation must be made:

1) All pots, pans and utensils that are impossible to thoroughly cleanse and which would be destroyed by koshering them with excessive heat, must be set aside and replaced.

2) Some pans or utensils have lips (such as certain types of sheet pans) or crevices (such as certain types of tongs). Since it is almost impossible to clean these areas thoroughly, it is advisable to discard and replace them.

3) Some colanders, or the like, are made of fine wire mesh or are cone shaped and come to a sharp point at the very bottom. These are also almost impossible to properly clean. They should be discarded and replaced.

4) The wooden handles of many knives become somewhat separated near the blade after much use. Since foodstuff tends to lodge within these crevices and it is very difficult to clean them properly, without dismantling and thus destroying them, they should be discarded and replaced.

The general rule is; if it cannot be properly cleaned before the koshering process and would be destroyed by applying excessive heat to it in the koshering process, it should be discarded and replaced.

The Dishwashing Machine

The Kosherability of the dishwasher is dependant on the makeup of its interior. The best Dishwashing machines, in terms of the kosher dietary laws, are those whose interior is made of stainless steel. Many high quality dishwashers belong to this category. Since they are made of stainless steel they are very easy to kosher. It is also much easier to maintain their kosher status, since if any mistakes are inadvertently made, causing them to become non-kosher, they are readily rekosherable. All industrial dishwashing machines are made of stainless steel and are easy to kosher.

Unfortunately, except for the most expensive, “Top of the Line” dishwashing machines, many standard home dishwashers are not of this kind. Their interiors may contain plastic, porcelain, enamel or a combination of these.

1) As we mentioned above, in most circumstances, porcelain may not be koshered.[30] Even in those cases that some authorities allow it to be koshered it must remain unused for a period of at least twelve months, and must then be koshered three times with boiling water.[31] Even if such a dishwasher could be koshered, one error, such as inadvertently washing meat and dairy dishes together with hot water, would render it non-kosher and unusable again. This type of dishwashing machine is unpractical for kosher homes and is not recommended. You should replace it, preferably with a stainless steel one.

2) As mentioned before, there is controversy as to whether metal overlaid with enamel may be koshered.[32] Though some authorities rule that it is kosherable if it is koshered three times with boiling water,[33] nonetheless, if the interior of your dishwasher is made of enamel, it is best to consult a rabbinical authority before proceeding.

3) As mentioned before, though the prevalent custom is not to kosher plastic, according to some opinions hardened rubber or plastic may be koshered.[34] Accordingly, if the interior of your dishwasher is made of these materials, it could possibly be koshered. However, as mentioned above, the interior of many home dishwashing machines may also include porcelain and may not be koshered.[35] Therefore, unless your dishwasher is made exclusively with a stainless steel interior, it is best to consult a rabbinic authority as to how to proceed. The procedure for koshering a dishwasher will be explained later.

The Toaster

It is difficult to kosher toasters for three reasons: Firstly, the bread-slots are too narrow and it is extremely difficult to thoroughly clean them. Secondly, the koshering process would ruin their electrical system. Lastly, they would have to be heated to extreme temperatures to be koshered. Since they are not built to endure such heat, it could destroy them. Therefore, the toaster may need to be replaced.

The Toaster Oven

Toaster ovens come in many different sizes, models and designs. Often, because of their size, they are very difficult to clean thoroughly. If your toaster oven falls into this category, it cannot be koshered and should be replaced.

Dishes, Cups, Saucers and glassware

If your dishes, cups, mugs and saucers are made of porous material, such as china, porcelain, ceramic or melmac etc. they will need to be replaced. There are differing opinions regarding glassware. As said above, Sephardic authorities follow the opinion of Rabbi Yosef Caro, the author of the Shulchan Aruch, and consider glass to be non-porous.[36] They are, therefore, lenient[37] in this regard. Accordingly, if you are Sephardic your glassware need only be thoroughly cleansed and may then be used. Ashkenazim, on the other hand, follow the opinion of the Rema, who says that glassware is similar to ceramics and cannot be koshered.[38] However, many Ashkenazic authorities agree that glass is non-porous or very near non-porous[39] and allow it to be koshered under certain[40] circumstances.[41] If you are Ashkenazic, consult a rabbinical authority if you wish to kosher your glassware.

Pot Lids and Handles

Just as pots and pans must be koshered, so also their lids, covers[42] and handles[43] must likewise be koshered.

Blenders and Food Processors

Since most home-use blenders and food processors are constructed of more that one material, such as metal, plastic and rubber etc. koshering them may be problematic. If your blender or food processor is of this variety it is best to replace it. If you desire to kosher it, consult your rabbi. After close examination, he may determine that it could be koshered. Heavy-duty blenders and food processors, manufactured for industrial use, are often built completely of stainless steel and may be koshered easily. If you are able, it is best to purchase this kind of food processor. Though they tend to be expensive they are very sturdy and will last a lifetime.


Since foods stuffs mixed by most mixers are cold, the mixer could therefore be koshered. This applies both to hand-held and stationary models. However, if you have used your mixer with hot items, this may be problematic. The stainless steel mixing blades may definitely be koshered. However, if the bowl is not made of stainless steel, a rabbinical authority should be consulted. He will determine if it can be koshered depending on the material it is made of.

Step Three

After everything has been sorted and it has been decided what will be koshered and what will be replaced, the next step is to clean everything that needs koshering.[44] This cleaning must be totally thorough, so that everything is as clean as humanly possible. Great care must be taken to make sure that the pots and pans have been scrubbed very well; making sure that no residual grease or food stuffs are left caked on their walls and that they are free of rust. This refers to the outer walls as well as the inner walls.

Mere discoloration on the vessel walls is insignificant to the koshering process. There is only a problem if there is substantive rust which, if scraped, will produce dust. Nonetheless, this only applies if the vessel will be koshered through immersion in boiling water or any lesser form of koshering. However, rust on a vessel that must be koshered by means of fire need not be removed since it will be utterly consumed.[45]

All the cooking and serving utensils, knives, forks, tablespoons and teaspoons, platters and mixing bowls must be washed and dried. Special care should be given in assuring that the oven and stove top are properly cleaned. If possible, all parts that may be disassembled from the oven and stove, or any other equipment, should be taken apart and cleaned separately.

It is not enough just to clean the top of the stove. Rather, the panel should be lifted and the interior cleaned of all grease that may have dripped in etc. When cleaning the oven it is important not to forget to clean the door, back wall, ceiling, corners and whatever crevices there might be. The racks and shelves must also be thoroughly scrubbed and cleaned. If there is a broiling unit, it must not be forgotten. It too must be scrubbed and cleaned.

In short, there must be a very serious cleaning of the kitchen. This being the case, if possible, it is advisable to hire a cleaning crew to perform all the difficult and menial tasks. However, it is important that they be instructed and supervised throughout the process to assure that they do as good a job as possible. Remember, the cleaner everything is, the easier the actual koshering process will be.

[1] ראה במדבר לא:כג, שו”ע או”ח תנה:ה, שו”ע יו”ד קכא:א

[2] שו”ע או”ח תנא:כא, שו”ע יו”ד קלה:טו

[3] שו”ע יו”ד צו:א-ב, דעת תורה למהרש”ם יו”ד צו:ב.

[4] שו”ע או”ח תנא:ח

[5] אג”מ או”ח ג:נח

[6] שו”ע או”ח תנא:ח, שו”ע יו”ד קכא:ב

[7] דרכ”ת יו”ד קכא:כה, שו”ת בית יצחק יו”ד ח”א- במפתחות סי’ קמו:ח, תבואות שור נג.

[8] שו”ע או”ח תנא:ח, ורמ”א שם

[9]  חתם סופר יו”ד קיג, שו”ת כת”ס יו”ד ע”ח, שו”ת מהר”ם שיק יו”ד קמ.

[10] ערוה”ש יו”ד קכא:ז, שו”ת מלמד להועיל או”ח צד, שו”ת רב פעלים ח”ג:כח, משנ”ב בשעה”צ תנא:קצא, שו”ת שבט לוי ב:מג, שו”ת חשב האפוד א:קיז, שו”ת בית אבי א:קח.

[11] ויקרא ו:כא, גמרא פסחים ל ע”ב, שו”ע תנא:א.

[12] מטעמי השלחן צא:יט.

[13] חכמ”א נה:ד.

[14]  אג”מ יו”ד ח”א מג, אג”מ יו”ד ח”ב מו.

[15] רמ”א או”ח תנא:כו.

[16] היינו בדיעבד

[17] שעה”צ תנא:קצו, משנ”ב תנא:קנה, ח”א קכה:כב, זרע אמת ח”ב יו”ד מג.

[18] שו”ע תנא או”ח תנא:כו.

[19]  יבי”א ח”ד יו”ד ה.

[20] היינו בדיעבד

[21] שו”ע יו”ד קלה:יב.

[22] משנ”ב תנא:קנו, צי”א ח”ח כ, וח”ט כו, משנה הלכות ט:קסח, שו”ע הרב או”ח תנא:ט.

[23] מחכמי אשקנז שבט הלוי ב:מג אסר, וצי”א ח:כא ומנחת יצחק א:פו התירו, ומחכמי ספרד הגר”ע יוסף שליט”א מתיר, והגר”מ אליהו שליט”א אוסר.

[24] שו”ת מנחת יצחק ג:סז, שו”ת חלקת יעקב ב:קסג, שו”ת אג”מ ב:צב.

[25] שו”ת אג”מ ב:צב

[26] ליבון קשה.

[27] ליבון קל.

[28] משנ”ב תנא:קנו, שו”ע הרב או”ח תנא:ט.

[29]  משנה הלכות י:צח, אג”מ אהע”ז ח”ד סוס”י ז.

[30] ויקרא ו:כא, גמרא פסחים ל ע”ב, שו”ע תנא:א

[31]   אג”מ יו”ד א:מג, אג”מ יו”ד ב:מו.

[32]  חת”ס יו”ד קיג, מהר”ם שיק יו”ד קם, שו”ת כת”ס יו”ד עח.

[33] ערוה”ש יו”ד קכא:ז, שו”ת מלמד להועיל או”ח צד, שו”ת רב פעלים ח”ג כח, משנ”ב בשעה”צ תנא:קצא, שו”ת שבט הלוי ב:מג, שו”ת חשב האפוד א:קיז, שו”ת בית אבי א:קח, שו”ת בית יצחק יו”ד מא מפתחות קמו, חזון עובדיה הגעלה ט.

[34] שו”ת מנחת יצחק ג:סז, שו”ת חלקת יעקב ב:קסג, שו”ת אג”מ ב:צב.

[35] קובץ מבית לוי ח”א עמ’ ל.

[36] שו”ע או”ח תנא:כו, שו”ע יו”ד קלה:ח

[37] שו”ת יבי”א ח”ד יו”ד, חזון עובדיה הלכות הגעלה ח.

[38] רמ”א או”ח תנא:כו.

[39] ט”ז יו”ד קלה:יא, וש”ך שם כתב שבליעת כלי זכוכית מועטת מאד.

[40] דהיינו בדיעבד.

[41]  ט”ז יו”ד תנא:ל, ש”ך יו”ד תנא:מט, שו”ע הרב או”ח תנא:עג, משנ”ב או”ח תנא:קנה, שער הציון תנא:קצו, חיי אדם קכה:כב, זרע אמת ח”ב יו”ד מג, ועוד.

[42] שו”ע או”ח תנא:יד.

[43] שו”ע תנא:יב, ורמ”א שם כתב שלכתחילה הכשרת הידיות יכולה להיות בעירוי ובדעבד מהני בלא הגעלה כלל אפילו בעירוי.

[44] שו”ע או”ח תנא:ג, שו”ע הרב או”ח תנב:ז.

[45] ט”ז או”ח תנא:ו.

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