Laws of Kashering Vessels - Rabbi Michael Shlomo Avishid shlita

00:02 Speaker 1 You’re listening to “Lema’an Yishme’u,” a podcast of Machon Halacha Chabad.

00:09 Speaker 2 With Hashem’s help, this class will deal with kashering the kitchen—or, in the language of our Sages, kashering utensils by immersion in boiling water. Before we focus on the utensils each of us has at home, we’ll first cover the foundations of these halachos. We have to begin by mentioning the final halacha in the Alter Rebbe’s Shulchan Aruch, section 452, paragraph 30. There he cites the poskim concerning a practice that continues to this day: even people without a real knowledge of these halachos undertake this work. He therefore writes that only a scholar well versed in these halachos should deal with it. Baruch Hashem, ignorance has decreased greatly in recent generations, because people can read, learn, and listen to classes. So, baruch Hashem, many people have some knowledge. But we must always bear in mind that it is very advisable to consult someone who understands the subject, in keeping with this straightforward halacha that only a scholar well versed in these halachos should deal with it. And as the Maharshal writes, both about these halachos and about the halachos of the Four Species, many speak about them, but few really know them. Especially when there are so many opinions and, at times, each person says something a little different, it causes even more confusion. Certainly, no one should decide on their own, “I heard this, so that’s what I’ll do.” One must consult a rav well versed in these halachos before kashering utensils. These halachos are not among the simplest. They are spread across several sections of the Shulchan Aruch: in Orach Chayim, among the halachos of Pesach, sections 451 and 452; in Yoreh De’ah, section 121; and there are other points scattered through the halachos of utensils and the halachos of mixtures, in section 202. So this is a subject with a great deal of material, many details, and many distinctions. The relevant Talmudic discussions are

02:52 Speaker 2 not that numerous, but one still needs to know them well in order to deal with this subject, or at least to be familiar with them. There is the discussion toward the end of tractate Avodah Zarah, from page 76 onward, as is well known. There is also tractate Zevachim, page 96, which discusses kashering utensils in connection with kodshim. Although we are not dealing with kodshim at present, it has interesting implications for kashering our utensils too. And there is tractate Pesachim, in the Kol Sha’ah chapter around page 30, which is generally studied in yeshivos. It too contains several important points and teachings of the early authorities that help define the halachos of kashering utensils. So, as a first practical rule, it is very advisable to consult a rav who knows this subject well, rather than rely on things heard from friends; get reliable information. If someone is concerned that they may not do it properly, then just as we spend money on many things, they can spend a little to bring in someone who knows these halachos and is accustomed to kashering utensils. They can pay that person to come and do it for them. That is the introduction to the class. It is very important to go over these points, even for people who do have some knowledge of the material, but whose knowledge, let’s call it, is superficial. They read many books and encounter many opinions, and it is not easy to decide based on the impression a book gives. Some books present something as entirely permitted according to most poskim, with only a minority disagreeing. Another book may present it differently. You cannot decide this based on impressions. As with any halacha, you need to know the subject thoroughly. If you don’t, you ask the qualified rav whom you usually consult on such questions, so that you can decide what to do. So, as I said, we’ll begin with some basic principles.

05:05 Speaker 2 The halachos of kashering utensils have their roots in the Torah itself, in Parshas Matos, concerning the war with Midian. The Torah speaks there about the soldiers who brought back spoils. Among them were utensils belonging to non-Jews, which were often ben yomo—used that very day. If the soldiers wanted to cook or roast in them, the Torah tells us, “Whatever comes into fire shall come into fire; into water, into water,” and so on. From this comes the well-known principle of kevo’o kach polto: the way something was absorbed is the way it is released. But we have to be very careful, because if we don’t study this in depth, the principle can be confusing. It is a general rule: if something was absorbed through fire, it is released through fire; if through hot water, then through hot water; and if through soaking in cold water, it can also be released through soaking in cold water, as we’ll discuss later. That is what kevo’o kach polto means. But we’ll see that we cannot use this rule for just anything that occurs to us. For example, when something is cooked in a pot, the pot does not necessarily reach an extremely high temperature. It might reach seventy degrees, eighty degrees, or a hundred degrees, but it does not always reach a high temperature. It does, for example, reach yad soledes bo, a temperature hot enough to make one’s hand recoil. So the question is: if a utensil was used at a yad soledes bo temperature, but the water did not boil—no bubbles rose, and it did not reach a hundred degrees—can it be kashered at that same temperature? If the food was absorbed at fifty degrees, will it be released at fifty degrees? If it was absorbed at seventy degrees, will it be released at seventy degrees? If we apply kevo’o kach polto simplistically, we might think so. But the halacha rules otherwise. At the beginning of section 452, including in the Alter Rebbe’s Shulchan Aruch, it is clear

07:16 Speaker 2 that if something prohibited was absorbed into a utensil in a kli rishon, a vessel used directly for heating, even at the temperature of yad soledes bo—which, according to the lower estimates, is forty-three or fifty degrees—then kashering it requires a kli rishon with boiling water, with bubbles rising. It has to reach a hundred degrees. So we see that it is not simply kevo’o kach polto: it was absorbed at fifty degrees and is released at a hundred degrees. It is very important to know that kevo’o kach polto does not work as simply as people think. Since we were speaking about a utensil that absorbed something prohibited in a kli rishon, we kasher it in a kli rishon. In that sense we can say kevo’o kach polto: it went in through a kli rishon and comes out through a kli rishon. A utensil that absorbed something prohibited in a kli sheini, a vessel into which hot contents were poured from a kli rishon—according to the opinions that are stringent and hold that a utensil can absorb in a kli sheini, which is a concern we take into account, certainly at least in the halachos of Pesach. In the halachos of Yoreh De’ah, the Mechaber and the Rema are fairly lenient. But at least the wording of the Mechaber in section 121, paragraph 2, indicates that initially we are stringent regarding a kli sheini. And Rabbi Kook [unclear] understood that “initially” means that if something prohibited was absorbed in a kli sheini, it should nevertheless be kashered, because that is the preferred course. Why use the utensil without kashering it if you can kasher it first? By contrast, if an earthenware utensil was used as a kli sheini, then since the Mechaber—and the Rema did not comment against his ruling—holds that if it absorbed something prohibited in a kli sheini it does not need to be kashered, one can rely on the view that a kli sheini does not cause absorption into a utensil. But there are opinions that disagree. The Taz there, in section 121, says that unless a substantial loss or something of significant value is involved, it does absorb. And in the halachos of Pesach, we are certainly stringent about this. So if something prohibited was absorbed in a kli rishon, we kasher in a kli rishon; if it was absorbed in a kli sheini, in a kli sheini. If it was absorbed through pouring from a kli rishon,

09:09 Speaker 2 It can be kashered by pouring from a kli rishon. So there, “as it absorbs, so it releases” does apply. But we see that with a kli rishon itself, even if something absorbed at fifty degrees, it will not release at less than a hundred degrees—at a boil. The Tzemach Tzedek emphasizes this even more strongly, saying that it must boil thoroughly. That means all the water, not just that at first a little water bubbles up at the top while the rest does not. “Thoroughly” means all the water must really come to a vigorous boil. When we normally kasher in a kli rishon, does the pot have to be on the fire? Kashering is very... as we’ll see, it happens very quickly. You put in the utensil that needs hagalah and leave it there. Some opinions say to leave it longer; others say it works immediately. So we leave it in for, say, two or three seconds and take it out. You could imagine taking a pot that is bubbling and turning off the flame. It won’t stop boiling that very second, so you quickly put the utensil in. Can you do that? As a matter of basic halachah, it appears that you can, even if the flame has been turned off. What matters is that it is a kli rishon: even if it has been removed from the fire, as long as it is still bubbling, you can use it. But the Alter Rebbe writes that this can be said regarding the laws of Pesach; regarding other prohibitions, we’ll see why not. In the laws of Pesach there are sometimes greater leniencies than elsewhere. It is specifically there that one may rely on this. But regarding other prohibitions, the Alter Rebbe rules in section 452 that one should be stringent and have the pot actually on the fire. The Pri Megadim writes this too, and that is the practice—certainly in light of the Tzemach Tzedek’s statement that it must boil thoroughly. Once you remove it

11:03 Speaker 2 from the fire, the boiling soon loses its full intensity. So today, when we kasher things that require a kli rishon, we always do it with the fire underneath. As you can see in the streets, where there is a cart, there is always a large flame under the pots, under the big barrels, because it is important that the water truly boil thoroughly. That is the accepted Jewish custom. Even though the Alter Rebbe wrote in the laws of Pesach that this is not necessary, in practice we are stringent. But I wanted to establish a principle here: “as it absorbs, so it releases” is not so simple. We can see another example with fire. Say a prohibited food was roasted on a spit, but it was not left there long enough to reach the level of intense libun described by the early halachic authorities. The Alter Rebbe gives two ways of identifying that level: either sparks fly from it—it can get so red-hot that if you strike it, you see sparks fly—or its outer layer peels off. Even today, when utensils are made somewhat sturdier, it is not easy to reach that second stage. Often, when we roast something—let’s say it is a prohibited food—the spit will not necessarily reach that kind of heat. Nevertheless, the halachah is clear that we do not apply “as it absorbs, so it releases” in that way. We do not say that because it became red-hot at two hundred degrees, it will release what it absorbed at two hundred degrees. Until sparks fly from it—and according to many halachic authorities that requires five hundred degrees, or even more, seven hundred—we have not reached the heat required for intense libun. Until then, we do not say “as it absorbs, so it releases.” It absorbed over a fire at a hundred degrees, without any liquid, yes, but it will not necessarily release it

13:06 Speaker 2 at that same level. It requires a level of heat at which sparks fly from it. So again, we see that we cannot apply “as it absorbs, so it releases” however we like. Those are roughly the principles. Now, since we have been discussing that phrase and I mentioned it even in connection with libun, that applies only in the sense that what entered through fire is dealt with through fire: we kasher the utensil using fire. But it is important to emphasize that hagalah and libun are two ways of getting rid of a prohibited substance, and they work in completely different ways. Hagalah—the word is related to a person feeling nauseated and sometimes vomiting; that is how some have explained it—draws the prohibited substance out. Hagalah expels it from the utensil. What does intense libun do? It burns up the prohibited food absorbed within the utensil. The fire does not expel it; it consumes it, as though turning something into nothing. That is a very different process, and it is very important to know this detail. Why? First, there is a rule in section 452 concerning how one should kasher a utensil in the first instance. Although, according to halachah, one can kasher a utensil that is ben yomo—one that was used with the prohibited food within the past twenty-four hours—how does that work? If you kasher it through hagalah, the prohibited substance has presumably come out of the utensil. What stops it from going back in? The early halachic authorities discuss this at length. Does the boiling cause absorption to be released but not absorbed again? There is considerable concern that it might be reabsorbed. That is one reason we do not leave a utensil in the water for very long: we take it out after two or three seconds. But it is written that one should not put it in and take it out instantly; hagalah must be given time to do its work. Still, we take it out quickly. But if the prohibited substance is now outside the utensil, what prevents it from going back in? Perhaps it will. Therefore,

15:18 Speaker 2 the practice today is to do hagalah on a utensil that is no longer ben yomo, after twenty-four hours have passed. Then, when the absorbed taste comes out, it is an impaired taste; according to most opinions, if an impaired taste enters a utensil in the first place, that utensil does not require kashering. In other words, even if it goes back in—yes, a utensil containing an impaired taste normally still needs to be kashered. Why? Because the taste was good when it entered and only later became impaired. But when it enters already impaired, as explained in section 103 of Yoreh De’ah, in principle the utensil does not need to be kashered. So the practice is to kasher utensils when they are not ben yomo. And when does this apply? Specifically to hagalah. Before this practice of doing hagalah on a utensil that was not ben yomo, one had to make sure there was sixty times the volume. If the utensil was ben yomo and the prohibited substance came out into the water, it was preferable to have sixty times its volume in the water. That way it would be nullified there, and even if it went back in, it would go back in already nullified in sixty. And of course, chametz before Pesach can certainly be nullified, and there is also the consideration that what was absorbed was permitted at the time, as is well known. In other words, strictly speaking, it was possible to kasher a utensil while it was still ben yomo; nowadays we kasher it when it is not ben yomo. This rule applies specifically to hagalah, not to libun. When we do libun with fire until sparks fly, the prohibited substance is not expelled. So what problem is there if the utensil is ben yomo? There is no concern that the prohibited substance will come out and go back in, because it is going to be reduced from something to nothing. Therefore, there is no requirement to wait twenty-four hours when doing libun. Sometimes, even with a utensil that requires hagalah, if someone is really pressed for time and it is possible to perform intense libun on it, that is another option; then there is no need to wait twenty-four hours. Another practical difference between

17:21 Speaker 2 The difference is that libun burns, while hagalah draws out what has been absorbed. There is a rule in the laws of Pesach that we do not perform hagalah on utensils during Pesach. In fact, the custom is not to do so once the time when eating chametz becomes forbidden has begun. At that point, we are no longer dealing with chametz that is permitted; we are dealing with chametz that is forbidden. All the more so on Chol Hamoed Pesach, when even the smallest amount of chametz makes something forbidden. Chametz becomes forbidden to eat by rabbinic law two hours before midday. Later, from midday, when the Pesach offering is brought, it becomes forbidden to eat by Torah law: “You shall not eat chametz with it.” But from the night of the fifteenth of Nissan, because the prohibitions against seeing or possessing chametz also apply, chametz becomes forbidden even in the smallest amount throughout the seven days. So we are certainly very, very careful not to perform hagalah on a utensil then, because the forbidden substance comes out and could go back in. And even if the utensil has not been used in the past twenty-four hours, as is known from section 447—and we will see it there, and the law states it explicitly again, I think in section 451, paragraph 43—the basic law is that a chametz utensil that has not been used in the past twenty-four hours does not make anything forbidden. That is the basic law. But the custom, at least among Ashkenazim and in Chabad, is that chametz makes something forbidden even in the smallest amount, even when the utensil has not been used in the past twenty-four hours. So performing hagalah on a utensil once chametz is forbidden, and all the more so during Pesach, is certainly out of the question. Libun is different. It is possible to perform libun on a utensil during Pesach or once chametz has become forbidden, as discussed in section 452. Why? Isn’t there a concern that the forbidden substance will come out and make something forbidden even in the smallest amount? No, because the purpose of libun is to reduce the substance to nothing. The forbidden substance is consumed. So it is important to know that libun

19:27 Speaker 2 actually burns. There is another kind of libun discussed in halacha, called light libun. Now, for something that absorbed through fire, we said that we do not apply the rule “as it absorbed, so it releases.” In other words, we do not use the same level of heat. Even if it absorbed through fire at 150 degrees, it releases what it absorbed specifically when the heat is high enough for sparks to fly off it. So where does light libun come in? Sometimes it applies to various kinds of utensils. First, there are utensils that can be koshered through hagalah. If hagalah can kosher a utensil, then light libun can certainly kosher it. In the Shulchan Aruch and the early authorities, we find two descriptions of light libun. One says that the required level is for the other side of the utensil to become yad soledes bo—hot enough that the hand recoils—when fire is applied to one side. In the words of the Magen Avraham, the hand cannot touch it. That does not take very long. You leave the fire on it for about half a minute, sometimes even less. It can happen very, very quickly, because when part of a metal utensil becomes hot, all of it becomes hot. Particularly on the other side, it will very quickly become yad soledes bo. That is one description given by the early authorities; the Mordechai mentions it, as do many others. There is another description: if, for example, a woolen thread were attached to the other side from the fire, it would burn. That is a somewhat higher temperature. Some have regarded these as the same thing, or as two options for light libun. But in practice, we see that the other side can become yad soledes bo very quickly, even if we use the stricter measure of 70 degrees. For a thread to burn there takes longer. That is still well before full libun, when the utensil actually becomes red-hot and sparks fly off it.

21:35 Speaker 2 So that takes less time than full libun, but more time than the first kind of light libun. People sometimes get confused about the Alter Rebbe, because in one place he describes light libun as heating the other side until it becomes yad soledes bo, while elsewhere he says that a thread on the other side would burn. But when you read his wording carefully—and many Chabad rabbanim have written this too—it is very straightforward: in principle, light libun means heating until the other side becomes yad soledes bo. There is no need to reach the point where a thread would burn there. So when does that second option apply? It applies to utensils about which there are opinions that might lead us to be more stringent and perhaps require full libun. Or, primarily, it applies when there may be chametz underneath some rust, in a place you cannot reach. Sometimes there are nails or other places where chametz can get in and be hard to clean. Here we can state another very fundamental rule about hagalah and koshering utensils: you cannot kosher a utensil unless it is completely clean. We learn this from the verse, “Only the gold”: it is the utensil’s material alone that must be koshered; there must be nothing else on it, no dirt at all. So sometimes dirt gets into certain places, and applying fire there presents a problem. If it is stuck somewhere with plastic, how can you do light libun on that spot? Or there may be glue there, and the heat could damage the utensil. Whenever koshering could damage a utensil, even if it is theoretically possible to kosher it—as the Alter Rebbe explains in the halacha concerning a horn, because of the horn’s material—it cannot be koshered. But when it is possible to kosher

23:36 Speaker 2 a spot where actual chametz may be hidden beneath some rust, light libun is mentioned. The utensil really requires hagalah, but because there is actual chametz hidden beneath some material, that chametz needs to be, more or less, consumed. How is that done? Through libun at a higher level. But when we want to kosher something that requires hagalah, the light libun required in its place is simply heating it until the other side becomes yad soledes bo, which does not take very long. Now the question is whether light libun can be used when we have a utensil so large that it cannot be put into a pot for hagalah. If it can be immersed in two stages, that is allowed: do one half and then the other. This should not be confused with what is explained in section 120 of Yoreh Deah about immersing a utensil in a mikveh. For that immersion, you cannot immerse one half now and the other half later. You have to immerse the whole thing at once, as with a woman’s immersion, when not even a single hair can remain outside the water. She cannot immerse part of herself and then immerse the rest. But with hagalah, that is not a problem. The point is to draw out the forbidden substance, so you first draw it out of one half and then immerse the other half. Sometimes, though, a utensil is so large that you cannot even immerse half of it; some part will always remain outside the water. In that case, light libun can be used, and light libun does not require such a high temperature. So, for example, in matters of meat and milk, many halachic authorities maintain that if I have a pareve utensil that was used for milk and I want to make it pareve again, then by all opinions it absorbed something that was permitted. We

25:25 Speaker 2 will discuss that later, and light libun can be done instead of hagalah. So if something became forbidden through a mistake involving an oven, you put it into the oven, even if it has been used within the past twenty-four hours. Why? Because light libun—and this is the additional rule—also consumes the forbidden substance, according to the Alter Rebbe. Of course, everyone will ask: if sometimes the heat must be high enough for sparks to fly off, how can light libun burn away the forbidden substance? This is a very well-known question. There are different levels of forbidden substances. The kind of forbidden substance for which a utensil requires hagalah is consumed by light libun. So does light libun draw out the forbidden substance, or cause it to be expelled? The Alter Rebbe maintains that just as full libun consumes it, light libun also consumes it. One practical difference is that you do not have to wait twenty-four hours. Another is that light libun can be done even during Pesach. Yom Tov is a separate matter. As for performing hagalah on a utensil on Yom Tov, since it is something that could have been done before the festival, we cannot do it if the need did not arise on Yom Tov itself. It is a preparatory act for work that could have been done before the festival, so it is not permitted, as is already mentioned at the beginning of the laws of Yom Tov, in section 495. Thus, koshering a utensil or performing full libun—or whatever libun halacha requires—on Yom Tov is a problem if the need did not arise on Yom Tov. This is discussed in the laws of Yom Tov, in section 509. But let us return to light libun. Light libun also consumes the forbidden substance. Some halachic authorities do not say that. The Pri Megadim seems to hold that light libun also draws it out,

27:18 Speaker 2 And so some argue that light libun should be done only to a utensil that has not been used in the past twenty-four hours. That can raise a question about kashering for Pesach. But our approach is that even light libun actually destroys the forbidden substance. So that is a very important detail. Another very important detail in the laws of kashering utensils: before we get to the practical side—and of course the goal of this class is to be as practical as possible—we cannot skip the basic principles. So let’s add a few principles quickly. The first is a concept discussed in Maseches Zevachim and also in Avodah Zarah: “it absorbed something permissible.” We see this with a utensil in which a korban was cooked. Many korbanos, such as a chatas, have a very short period during which they may be eaten: one day and one night. During that time, the korban is fit for the kohen to eat. Afterward, once its time has passed—two days for some korbanos, one day for others—it can become nosar, which is forbidden in every respect. Even the kohen may not eat a korban after its allotted time. So what about the utensils? The korban itself is eaten in its proper time, but some of it is absorbed into the utensils. Seemingly, what is absorbed will then become nosar, and the kohen will be unable to use the utensil to cook the next korban, because it contains something forbidden. The Gemara says there is a concept of “it absorbed something permissible.” We said that when something forbidden is absorbed through fire, it must be kashered specifically through fire, until sparks fly off. You cannot, for example, use light libun or hagalah for a utensil that requires severe libun. But that applies when what was absorbed was forbidden. The meat of the korban, when it entered the kohen’s utensil, was permissible: the utensil absorbed something permissible. So when something enters a utensil while it is permissible,

29:29 Speaker 2 even if it eventually becomes forbidden, we do not apply the rule for something forbidden that was absorbed through fire. It can be kashered through hagalah. The big question concerns meat and milk, and chametz. Our subject here is chametz, but let’s say just one thing about meat and milk: the Alter Rebbe holds that it is considered a case of “it absorbed something permissible,” because the meat and milk were not absorbed together. In other words, even if someone cooked milk in a meat utensil, and even if it was used over fire without water, so that severe libun would otherwise be required—and there are sometimes utensils, such as baking pans, that cannot undergo severe libun; we’ll discuss that—it can be kashered through hagalah or light libun. Why? Because with meat and milk, it is considered to have absorbed something permissible. Many halachic authorities disagree. They say this applies only if a pareve utensil absorbed milk: then it absorbed only something permissible. Or if a meat utensil absorbed milk more than twenty-four hours after it was used for meat. As ruled in Yoreh De’ah, siman 93, the utensil still needs to be kashered, but the milk did not encounter the meat’s fresh taste. When I cook milk in a meat pot that has not been used in the past twenty-four hours, the two do not meet as actual forbidden substances. So many agree that this is a case of “it absorbed something permissible.” But if the milk was absorbed two hours after the meat, many say no: that is no longer the case. There is still a fresh taste inside, and it comes back out as well. But the Alter Rebbe, in siman 452—sorry, in siman 451, section 13—has a gloss in which he argues that this

31:22 Speaker 2 too is a case of “it absorbed something permissible.” That can help us rely on light libun when mistakes involving meat and milk occur, even where severe libun would otherwise be required. Our big question is about chametz. Is chametz considered something permissible when it is absorbed? Seemingly, yes: it enters the utensil while it is permissible. Before Pesach, chametz is permissible, so this should fully qualify as “it absorbed something permissible,” even though it eventually becomes forbidden. All right, perhaps that is just like nosar. But the Rishonim disagree on this point. It is a major dispute. Many Rishonim—the Rif, apparently the Rambam as well, and many others—say that chametz cannot be considered a case of “it absorbed something permissible.” Why? Because nosar is the meat of a korban, and it is not called nosar until that new status takes effect when its permitted time has passed. The utensil did not absorb nosar; it absorbed meat, which only later became nosar. Chametz, by contrast, is called chametz even beforehand. Although it is not yet forbidden, it already bears that designation from the outset. Therefore, they say, we cannot rely on the leniency of “it absorbed something permissible.” Other Rishonim disagree and say that we can. In the Shulchan Aruch, the Beis Yosef and the Alter Rebbe rule that we must take into account the views that do not consider chametz a case of “it absorbed something permissible.” Therefore, whatever requires libun requires libun; it cannot be kashered through hagalah. Nevertheless, throughout siman 451 we will see several occasions when this view can be combined with another consideration to permit something. So when the Alter Rebbe rules on whether chametz is considered something permissible when absorbed, let’s take a simple question: someone used a skewer over fire with chametz, for example, so it required severe libun. Before Pesach, he performed hagalah instead of severe libun, and then used the skewer during Pesach. Can we rely after the fact on the view that it absorbed something permissible, or is this only a rule about what should be done in the first place?

33:22 Speaker 2 The Alter Rebbe rules that even after the fact it is forbidden. Only where there is a substantial financial loss, or where it would affect the joy of Yom Tov and so on, is there room to permit it. Still, there is a well-known principle that the Rema states in his Sefer Toras Chatas: when a halachic authority holds that something may be permitted in a case of substantial financial loss, that shows he thinks it should, strictly speaking, be permitted. That is a significant point, but it makes a great deal of sense. After all, money certainly does not outweigh a prohibition in Judaism. In Yoreh De’ah, siman 157, we learn that there are three transgressions for which we must give up our lives rather than transgress. For other transgressions, we need not give up our lives. But if no one is threatening to kill a person—if he is told, “Listen, either eat non-kosher food or, G-d forbid, I’ll burn all your possessions”—then according to halachah, one must be willing to lose all one’s money rather than violate a prohibition. Why? Because there is no financial limit when it comes to a prohibition. For a positive mitzvah there are limits; there is a boundary. But when it comes to refraining from something forbidden, there is no financial limit. So how could we allow a leniency because of substantial financial loss? It makes no sense to permit a prohibition for the sake of money. Rather, the halachic authority holds that it is permitted according to the basic law. But because the stricter views are nevertheless those of very important halachic authorities or Rishonim, he takes them into account and rules stringently. Sometimes he is less concerned about them, so he rules stringently in the first instance but leniently after the fact. Here, he does not readily permit it after the fact; he permits it in a case of substantial financial loss. But we can already see that the view that chametz was permissible when absorbed is nevertheless used after the fact. And there are cases where we rely on it almost from the outset,

35:19 Speaker 2 as the Alter Rebbe discusses in siman 451 regarding knives. The discussion in Pesachim, page 30, also implies that knives should not be kashered and that new ones should be bought. But ultimately, if a person needs his knives, there are two considerations that come together. One is the concept that they absorbed something permissible: sometimes people cut hot chametz inside an oven, and that could happen with a knife. Some would even use knives to roast something over a fire, so absorption through fire is possible. Nevertheless, the Shulchan Aruch rules that they can be kashered through hagalah, because there is the view that they absorbed something permissible, together with another view. And this brings me to the second very important principle: the Rishonim discuss whether we follow a utensil’s primary use or its occasional use. We see this both in the laws of Pesach in siman 451 and in Yoreh De’ah, siman 121. Do we follow its primary use? What do the halachic authorities hold on this question? It is a very practical one. If a utensil is generally used with something forbidden while cold, and only occasionally, in rare instances, used with it while hot, do we say it can be kashered as something used cold and disregard those rare instances? Or suppose a utensil is used with water in a way that requires hagalah, rather than absorbing through the heat of fire, but on rare occasions it does absorb through fire. Do we say that we follow its primary use, and since it is mainly used with water, we perform hagalah? Or, because it is occasionally used over fire, do we require libun?

37:32 Speaker 2 So in this dispute, the Beis Yosef holds—and this applies to the laws of Pesach as well as other prohibitions—that we follow an item’s predominant use. For Sephardim, this leads to considerable leniencies. That is not the position of the Rema and the Alter Rebbe in section 26 of siman 451. The Alter Rebbe rules that, initially, we do not follow an item’s predominant use. Interestingly, though, even according to the Alter Rebbe, if an item was kashered based only on its predominant use, without taking its less frequent use into account, we may be lenient after the fact. So we have two important principles here. One is that this is called heiteira bala—it absorbed something that was permitted—and the Alter Rebbe rules that we may be lenient on that basis only in a case of substantial loss or where Yom Tov joy would be diminished. He says this in section 13 of siman 451. The second discussion, also a very fundamental one in the laws of Pesach, is an item’s predominant use. On that, the Alter Rebbe rules to be stringent initially and lenient after the fact. Let’s add two more basic principles of kashering utensils and get straight to the practical work. I hope these principles will help with the practical matters ahead. Not every utensil can be kashered. There is a discussion in the tractates Zevachim and Pesachim about earthenware vessels. The Torah speaks, for example, about an earthenware vessel used for consecrated food, and says that a vessel in which it was cooked must be broken. Why must it be broken? From here the Torah attests that an earthenware vessel never releases what it has absorbed. In other words, the Torah tells us that earthenware does not release the forbidden substance it has absorbed, so it cannot be kashered. Just to give a little more detail about earthenware: when we say it cannot be kashered, we mean either earthenware that absorbed something hot and therefore requires hagalah—kashering in boiling water—which cannot be done for it, or earthenware

39:51 Speaker 2 that absorbed chometz through pickling—where the chometz was absorbed in a sharp liquid. We know there is a halachic concept of pickling. Ordinarily, it takes twenty-four hours, but pickling happens faster when the liquid is sharp. The absorption then takes place more quickly, within the time it would take to put the liquid on the fire and bring it to a boil. Imagine putting that same amount of water on a medium gas flame: how long would it take? If it’s a little water, it boils in two minutes. If there’s more, ten minutes; still more, twenty minutes. That is the measure for rapid pickling: the time it takes to bring it to a boil on the fire. That is how a forbidden substance is absorbed through a sharp liquid. Some poskim want to say that rapid pickling in a sharp liquid does not cause absorption into a utensil; it applies only when the substances themselves are present and absorb into each other. But the Alter Rebbe holds, in siman 447 and also in the laws of Pesach in siman 451, that rapid pickling does cause absorption into a utensil. By contrast, according to the Alter Rebbe, rapid pickling does not draw anything out of a utensil in less than twenty-four hours. This is contrary to the well-known position of the Derishah in the laws of salting, that rapid pickling also draws substances out of a utensil. So, ultimately, if an earthenware vessel absorbed something hot, or absorbed something through rapid pickling in a sharp liquid—pickling in a liquid that is not sharp is a different matter—then the vessel requires hagalah, but it cannot be kashered through hagalah, because the Torah attests that hagalah does not work for earthenware. That is different from an earthenware vessel that absorbed in another way. Now, earthenware today includes ceramics and porcelain, and also a mixture of glass and clay which, as the Mordechai says, were fired together. That, too, gives it the status of earthenware.

41:50 Speaker 2 So all vessels defined as types of earthenware, which were placed in a kiln as earthenware is made—there are other methods too, but this is the kind of vessel about which the Torah attests that it never releases what it has absorbed—cannot be kashered that way. By contrast, if it absorbed something cold—for example, if pieces of chometz sat in water that was not sharp for twenty-four hours, and the earthenware absorbed chometz—the Torah did not attest that such an earthenware vessel cannot be kashered. It can be kashered through hagalah or through filling and emptying. This is explained later, at the end of siman 451, regarding earthenware. Filling and emptying means filling it with water for twenty-four hours, pouring the water out, then filling it again for twenty-four hours and pouring it out again. You do that three times. This is called filling and emptying three times. We also find this concept in the laws of wine used for idolatrous purposes, as is well known. So it is not simply the case that earthenware can never be kashered. Sometimes, if it absorbed through cold use, without sharp chometz or a sharp substance, it can be kashered through hagalah or through filling and emptying. There is another possibility: if the earthenware vessel was like an oven, with coals placed inside it to heat things, then, because it is accustomed to contact with hot coals, there is no concern about doing that again and giving it a thorough libun—kashering by intense heat. When the Torah attests that earthenware never releases what it has absorbed, it means it cannot be kashered through hagalah. But

43:36 Speaker 2 a thorough libun can certainly kasher it, and sometimes even a lighter libun may suffice. If it is returned to the kiln, that is clearly fine. So why don’t we generally kasher earthenware through libun? Because there is a concern: these vessels are fragile and could be damaged. With any vessel that could be damaged, we don’t accept someone’s assurance that he is willing to damage it and doesn’t mind. We go by the usual tendency: a person generally does not want to damage his vessel; he is protective of it. So if it is an earthenware vessel that normally receives food on the inside while the heat comes from below, then, as we say, “The way it absorbs is the way it releases”: what went in from the inside must come out from the inside. But putting fire inside could ruin it. By contrast, an earthenware vessel normally used with fire inside can certainly be kashered this way. Those are just some basic principles regarding earthenware. In practice, the Jewish custom, cited even in the Beis Yosef’s Shulchan Aruch—which uses a somewhat Aramaic expression here—is: forget about earthenware. We do not use an earthenware vessel that has ever been used with chometz, even if it was used with cold chometz for less than twenty-four hours. In other words, nothing was absorbed into the earthenware at all. The point is simply that the earthenware was once used with chometz, even cold chometz, without absorbing it. A person took a porcelain cup and once—or several times—put a little chometz with water in it, and it was not hot. It doesn’t matter. It is an old chometz vessel, meaning it was used with chometz at some point. The Jewish custom is not

45:26 Speaker 2 to use earthenware vessels. One final principle: let’s talk about glass vessels. Glass vessels are the subject of a dispute among the Rishonim. The Alter Rebbe’s Shulchan Aruch brings about three opinions, and there are more opinions on the matter, including that of the Radbaz. One is the opinion of the Raavyah, which is the official ruling of the Beis Yosef’s Shulchan Aruch: glass does not absorb anything at all. Even if it was used with hot chometz, it does not need to be kashered. It’s a wonderful material—a vessel that absorbs nothing. Rabbeinu Yechiel of Paris disagrees. He says that not only does glass absorb, but since it is also made from sand, it resembles earthenware and has the same status. Incidentally, the Alter Rebbe explains that, according to the stricter opinion, glass is treated even more stringently than earthenware. How could glass be treated more stringently? We said earlier that if earthenware absorbed through pickling without a sharp substance, it can be kashered through filling and emptying. The opinion that glass cannot be kashered says that even filling and emptying does not work for it. In that respect, glass is worse than earthenware. There is a very well-known discussion of this by the Tzemach Tzedek in his Chiddushim or responsa, I think, dealing with this question. So one opinion says glass needs no kashering at all; another says kashering will not help, and treats it even more stringently than earthenware; and a third says it can be kashered, and once it is kashered, it is fine. The Beis Yosef ruled like the Raavyah, that no kashering is needed at all. For Sephardim, that has enormous lenient implications for all glass vessels. Some are nevertheless stringent and have a custom to be stringent. But in principle, the Beis Yosef’s position is lenient regarding glass: it does not absorb. And many say that this applies even if other materials are mixed into it when it is melted, as is done today

47:34 Speaker 2 Duralex, Pyrex, and all kinds of glass. The Tzitz Eliezer even writes that some metallic substance is sometimes added to almost every type of glass. But that makes no difference, because the surface is smooth, as the Raavyah says. It is very smooth, and he compares it to the heart in the laws of salting: the heart is smooth and supposedly does not absorb certain things. We won’t go into section 72 of the laws of salting now, but because glass is smooth, it does not absorb. That is one view. There is another view among the Rishonim, that of the Radbaz, who says that glassware can be kashered. The issue is that glassware can sometimes crack and break, so the custom was not to kasher it. According to the Radbaz, the ruling would be different today for Duralex and Pyrex—types of glassware that can withstand kashering. Those are, more or less, the views established among the Rishonim. The Mechaber, as we said—the Beis Yosef—is lenient about this. The Rema and the Alter Rebbe are stringent about glassware. Let’s focus on the Alter Rebbe’s approach, at the end of section 451, perhaps from subsection 78 onward: we are concerned that glassware is worse than earthenware and cannot be kashered. And there is the famous story about the Alter Rebbe and the glassware. But ultimately, if someone did kasher it, relying on the opinion that it can be kashered, what would the ruling be if, during Pesach, a person used that kashered glassware for something hot? Would we rely on the opinion that it can be kashered? The Alter Rebbe says yes. After the fact, one may be lenient with glassware that was kashered. But what if glassware was not kashered at all, and something was heated in it during Pesach? Could we rely on the Mechaber’s view, the Raavyah’s view, that it does not absorb at all? To that, the Alter Rebbe says no. So if—and there is a principle, not stated here by the Alter Rebbe but brought in the Shulchan

49:43 Speaker 2 Aruch and cited by many poskim, that sometimes, when a posek is lenient after the fact but not initially, in a case of great difficulty the initial situation is treated like an after-the-fact one. In other words, according to this principle, if a person has no choice but to use and kasher glassware, since the Alter Rebbe is lenient after the fact once the glass has been kashered, there is sometimes reason to say that one may be lenient and kasher it from the outset: the person is in a difficult situation, and that is considered like an after-the-fact case. This is a very well-known principle among poskim. Some wanted to apply it to subsection 13, regarding the law of hetera bala, where the absorbed substance was permitted. But there, one cannot use this principle, because the ruling is not lenient in an ordinary after-the-fact case. It is lenient only in a case of substantial financial loss or where Yom Tov joy would be prevented. But where the ruling is lenient after the fact, this concept does apply. That covers the general principles. They took a little while, but now let’s go straight into the most practical part: kashering the utensils we have in our homes. First, ovens. Household ovens, many of which have a pyrolytic setting, reach temperatures of 200, 250, or 280 degrees. That certainly does not amount to libun chamur, intense heating. So, as is well known, kashering such an oven is not recommended at all. Now that we have covered some of the principles, we can begin to understand why. First of all, we have certainly baked chametz in the oven during the year—cakes, challahs. We’ve baked in it plenty of times. Now it is very important to mention a halachah in Shulchan Aruch, section 451, to address the oven question. Sometimes, when people baked cakes, there was a cover over the cake pan. This was called the cover over the cake. The Shulchan Aruch writes that this cover requires libun chamur. Why? The Tur gives two explanations. One is that many

52:07 Speaker 2 times the cake rises and touches the cover itself. If it touches the cover and there is no liquid through which it is absorbed, the chametz goes directly into it. That is why libun chamur is required. Even though the heat in today’s ovens is not an actual flame but comes from a metal element that heats up and radiates heat inside the oven, that too is considered fire, as is well known. So because the cake rises and touches the cover, libun chamur is still required. The Tur gives a second reason: the chametz gives off steam. Even if it does not touch the cover, there is steam from the chametz, and because that steam comes into direct contact with the cover, libun chamur is required. It is very interesting that the Magen Avraham also brings both of the Tur’s reasons for requiring libun chamur for the cover over the cake. But the Alter Rebbe omits the second reason. He brings the first reason, that the cake touches it, but not the reason involving steam. Some therefore wanted to suggest that perhaps food does not give off steam that has halachic significance at all. But we need to state a simple principle: steam, too, can make something forbidden. We learn this in the laws of meat and milk, section 92. In subsection 8 there, we see that steam can make something forbidden. There is the famous responsum of the Rosh about a dairy pan containing milk with a pot above it; the Terumas Hadeshen also brings such a case. Even when the rising steam has some room to disperse to the sides, if the steam that reaches the pot is hot enough that a hand would recoil from it, the meat pot above requires sixty times the amount of milk below. There is a discussion there about whether that means sixty times the steam or all the milk, but we see that steam can make something forbidden. That is straightforward. Can steam also make the food below forbidden? The Pri Chadash and Pri Megadim discuss

54:15 Speaker 2 that question. They all deal with it, but we see plainly in section 93 that if someone mistakenly took a dairy lid and covered a pot of meat that was cooking, the meat also becomes forbidden. There is even a stringency there concerning a lid that had not been used within the past twenty-four hours. We won’t go into the Rashba’s explanation or the others’, but we see that steam can also make what is below forbidden. Perhaps, though, that is because the steam has nowhere to escape: it is a lid, and the pot is virtually sealed. Even if a little steam escapes around the sides, it is still closed. Some question whether steam can make what is below forbidden when there is some room for it to escape. Today’s ovens also have some internal ventilation that removes some of the steam and smoke inside. Still, we can picture steam rising to the oven walls. So the question is whether that makes them forbidden. And, as I said, the Alter Rebbe omitted the second explanation. Why? Now that we have explained some principles—that steam can make what is above forbidden and can also make what is below forbidden—we can note that the Alter Rebbe holds this way as well in the laws of Pesach, section 451. Later, when he discusses the oven, he says that steam can also make what is below forbidden. It creates a kind of connection: the smoke rises, the steam rises, and they form a connection. Now, we should not confuse this with another issue. With ovens, the discussion is often not about steam but about aroma. Anyone who has studied a little of Yoreh Deah, section 97 at the end of the laws of meat and milk, and section 108, knows the discussion of reicha milsa—whether aroma has halachic significance. The Alter Rebbe, too, speaks a great deal about aroma in an oven containing chametz and matzah. Aroma is not as substantial as steam, and there are therefore opinions that are lenient about it, particularly with chametz, which is not fatty.

56:11 Speaker 2 The Alter Rebbe says in siman 447 that even if the challahs were kneaded with oil, the oil is absorbed into the bread itself. This is not bread coated with oil on the outside, where oil was spread on it—that already makes it greasy. Rather, this is bread kneaded with oil: when they added the water and flour, they added oil and kneaded it all together. Halachically, that is considered something without grease, and therefore the law of steam does not apply. Seemingly, the law of aroma does apply. But when there is steam, you can see that the steam makes what is above forbidden. Steam can also make what is below forbidden. The question is whether foods actually produce halachically significant steam; that is a matter of debate. The Pri Megadim and others discuss this in siman 92, se’if 8, and elsewhere in the Shulchan Aruch. Is there steam from foods with regard to the laws of making things susceptible to tumah? In the end, it is clear from the Tur that there is. Now, why does the Alter Rebbe omit this? It may well be that there is steam sometimes. So why, when discussing an oven in siman 447, does the Alter Rebbe speak of aroma rather than steam? He therefore says that if chametz and matzah were baked at the same time without touching each other, they do not make each other forbidden—at least in the ovens of those days—because this is the aroma of something without grease. But here we are dealing with steam, because our small ovens may very well be somewhat like the case in siman 93, where I have a lid on a pot and there is steam. Perhaps that case is specifically about foods, but many poskim maintain that foods do produce steam. So it is not so simple to assume that they do not, especially since there is an explanation for why the Alter Rebbe omitted the Tur’s second reason. It is not to say that there is no steam, but only that the reason a full libun is required is that the chametz touched the surface

58:10 Speaker 2 directly. But when steam touches it, that is essentially vapor, essentially like water. So perhaps full libun would not be needed for steam; hagalah would suffice, while full libun is needed only when the chametz touches it. After all that background, we can talk about the oven. In today’s oven, there may very well be steam. Some want to say there is none, particularly in ovens where the metal heats up—that is, where the heating elements are inside the oven itself, rather than beyond the walls or inside them. So, seemingly, any steam rising there burns up immediately. Nevertheless, certain experiments, including at the Halperin Institute, found vapor, sometimes even from foods and challahs. We can discuss today’s ovens in light of the fact that they are made of metal. Ovens used to be made of earthenware or stone. We also see in siman 108 of Yoreh De’ah that the Rema mentions in se’if 1—and many inferred from his wording—that the discussion concerns even dry foods: if there is a cover, if the cooked food or dry item was placed under a pan, there is steam. True, the wording does not establish with certainty that there is steam, but over the course of the year there is certainly reason to suspect that there is a lot of it. Now, since the Alter Rebbe omitted the reason of steam and mentioned only chametz that touches, what about today, when we put food in baking trays? The oven’s own tray clearly cannot be kashered. The chametz—the challah—touches the tray. What must be done with the tray? Even if it is metal rather than enamel—and we try not to kasher enamel; we are particular about that, though this is a dispute that began in the Rambam’s time, involving the Sifra and many other poskim—even a metal tray of the kind used today often cannot withstand it. If it can withstand a full libun, excellent, but often it cannot. The household baking trays we have cannot withstand

1:00:11 Speaker 2 a full libun, whether they are enamel or not. They can simply warp. Don’t try it; and halachically, one may not test things this way. So we certainly do not kasher baking trays. But how did the oven absorb chametz? Here it is not like the lid of a pot. The oven did not absorb chametz because it touched the walls, but through vapor. Yet everyone knows what happens. Just come and look inside our ovens over the course of the year. Sometimes children—or someone who wants a boureka before it is ready and cannot wait for it to come out of the oven—reach in and drop some of the chametz. Someone wants to grab a piece of challah along the way. There are always sesame seeds that touched chametz, and pieces of chametz lying there. The oven gets dirty. It is not even so clear that one can call this “a minority of its use,” saying that most of its use involves steam and only a minority involves direct contact, because things fall in so often. Fine, someone will say that the oven’s heat often burns them up. But you can frequently find that this happens. And even regarding an item’s predominant use, we have ruled that, ideally, we do not rely on that principle. So for those looking for leniencies—and sometimes there are people who are becoming involved in Jewish observance, and so on—there is room for discussion. If one wants to combine grounds for leniency in the Shulchan Aruch, one can say that this is [unclear]. One can also cite the opinions that say, “As it absorbs, so it releases”: it absorbed at that level of heat. That is even though, as we said, when a full libun is required, there is no principle that it can be released at the same temperature at which it was absorbed. Still, one can combine many, many opinions. There is another problem with the oven, too. There is glass, and often there is also rubber. The rubber is not quite as bad, but the glass is something that, ideally, cannot be kashered. So

1:01:59 Speaker 2 one certainly should not undertake to kasher ovens as a matter of standard halachic practice. In specific cases of pressing need, we sometimes give the option of putting coverings inside, covering part of it with very thick aluminum foil and securing it very firmly, or even taking a shelf and screwing it on so as to get around the glass somewhat. Some also want to say that the glass is not such a serious problem, since the Alter Rebbe was lenient about glass utensils after the fact, and here it is a case of pressing need. So if there is pressing need, there is room to discuss it. But, thank G-d, we have many options for cooking and heating food on Pesach. One can make a one-time purchase and then have an oven for every Pesach. So it is a shame to kasher an appliance like this—an oven with so many questions—when, according to the basic law, because chametz has so often fallen against its walls, it requires a full libun. Two hundred and fifty degrees is not a full libun. Now there are self-cleaning pyrolytic ovens that reach five hundred degrees. Many poskim, including Chabad rabbis, say that five hundred degrees is sufficient; other Chabad rabbis say it still is not. I remember asking Rabbi Mordechai Eliyahu, a"h, when I was young, and he told me he wanted it to reach much higher than that. I don’t know—I don’t remember—something like seven hundred degrees. I was very young when I asked him. In short, it is not simple. Don’t undertake this on your own. When it is necessary, ask a rav. There are a number of grounds for saying that direct contact is only a minority of the oven’s use, that its predominant use is otherwise, and for combining various other considerations. But it is best not to rely on leniencies for an oven. There is also a problem with a microwave.

1:03:49 Speaker 2 Very, very serious. What’s the problem? It is constantly exposed to steam. Sometimes you put in pizza and the like, and it is exposed to steam from chametz. Besides the fact that the food touches the plate, let’s say we even replace the plate, so we have a new plate, and clean everything. Some have suggested kashering the microwave by putting water, or water and soap, inside and letting the water evaporate. “As it absorbed, so it releases”—the absorbed taste would come out in the steam. This is a very, very, very serious problem. I know that many seforim have cited the leniency of kashering a microwave in general, and mistakes with meat and milk in a microwave do happen. Sometimes, because something is heated for only a minute, that is not long enough for the walls to heat up, and the steam reaches them cooler, since the walls are not hot. What is hot is the food; the heat comes from the food. But when you leave it in for three or four minutes, it certainly heats up. Tests have been done with a thermometer that withstands high temperatures, and they found that the walls can reach sixty or seventy degrees just because of the food. The food gives off heat because of the friction—the way the microwave works—and releases heat. Now, how can you put in a cup and kasher it with steam? Where have we seen that kashering with steam is possible? It is not simple. The Shulchan Aruch even says the opposite. In siman 451, it says: How do you kasher the lid of a pot? It requires hagalah, immersion in boiling water. That is the wording of the Shulchan Aruch. The Alter Rebbe says so too: it requires hagalah. Why hagalah? Why don’t we say, “As it absorbed, so it releases”? It entered through steam; it should leave through steam. Because perhaps we have no precedent for kashering with steam. The Pri Chadash discusses this at length in siman 451, se’if 15, I think, and he wants to say

1:05:50 Speaker 2 that it is possible. But many poskim say it is not. In any case, we have no clear source among the Rishonim, or in the Shulchan Aruch, that kashering with steam is possible. We should not get confused by the following example: Say we took a meat pot and mistakenly heated milk in it to half the pot’s height. How do we kasher it? After twenty-four hours, we fill it halfway with water, and “as it absorbed, so it releases.” We do not need to fill the pot any higher. This comes up with Pesach. When kashering a pot for Pesach, sometimes the chametz reached higher. You put in soup with noodles up to one level, sometimes it reaches higher, and sometimes it even spills over. So in that case, the water must reach the top and even beyond; you have to make it overflow. Sometimes they take a very hot, heated stone and drop it into the boiling water, making it overflow. Or they would sometimes make a rim of clay so the water could rise even higher and then overflow with the heat. But that is because, during the year, the chametz reached very high. If the prohibited food reached only a lower level, the pot can be kashered to that same level: “As it absorbed, so it releases.” You might ask: But there is steam above that level. The answer is that it will be kashered. The poskim said it will be kashered in the same way that it absorbed the taste, and that is how it will be released through... But we cannot learn from this that kashering with steam is possible. Since the pot is filled with boiling water, “as it absorbed, so it releases”: together with the steam and the water, the prohibited taste will go into the water. Or perhaps this can be done only when there is water there. So it turns out that, apart from the Pri Chadash, we have not found a substantial source allowing kashering with steam. That is why kashering a microwave is a very, very big problem. Now, there are microwaves with

1:07:48 Speaker 2 a browning feature, right? With heating that makes them a little more like an oven, and we said that it is not advisable to deal with kashering those either. But certainly, most of the microwaves we have present a problem, because we have not found in halachah that kashering with steam is possible. Something rendered prohibited through steam is kashered by hagalah. That is what the Shulchan Aruch says about a lid. There, we did not say it was because water touches the lid; it simply requires hagalah in boiling water. Water rising from the bubbles has the status of a kli rishon. So don’t try to kasher a microwave. Then there is the question of the sink at home. Often a sink is made of stone or marble, or sometimes of a stone composite made from several pieces that are bonded together and placed briefly in an oven. It is certainly not quite like earthenware. Some have wanted to be stringent when a sink is made from several pieces of stone. But the Alter Rebbe, in siman 451, se’if 25, does not seem to consider this a problem. It should not be treated more stringently as long as it is not like earthenware in the way it is made and fired in an oven. Earthen vessels are also earthenware. But if it was not fired in an oven and was instead dried in the sun, it may be kashered by hagalah, like stoneware. Most utensils can be kashered. The exceptions are earthenware, glassware as we discussed, and sometimes utensils that might be damaged; but in principle, kashering is possible. So someone who has marble of that kind, or marble with other materials—or wood, too—can kasher it. Now, what if it is painted? It is true that the Shulchan Aruch says a painted item is a problem because the paint prevents it from releasing absorbed taste. But if it was painted beforehand, before it absorbed the prohibited taste—if we bought it already painted—it seems there is no halachic problem. We will come back to wood,

1:09:42 Speaker 2 because sometimes there is a concern that it will be damaged, and people are hesitant to kasher it. But take a very common sink, or a metal, aluminum, or stainless-steel sink. All of these can be kashered. So what do we do? We need to kasher them according to the Shulchan Aruch. Strictly speaking, they should be kashered by pouring hot water from a kli rishon over them, because that is how hot substances generally reach them: poured from a kli rishon. Sometimes things spill into them. That is the basic law. The Alter Rebbe cites the view of the Chok Yaakov, quoting the Maharil, I think, that both pouring and a heated stone are needed. Why? Because from time to time people put a kugel in the sink. This brings us to a very well-known subject in halachah: a davar gush, a solid piece of hot food. The Mechaber and the Rema are fairly lenient about this, both in the laws of Shabbos and in Yoreh De’ah. And even the Magen Avraham—whom almost all the contemporary compilers, without exception, cite as stringent regarding a davar gush—in the Magen Avraham at the end of siman 318... The Tzemach Tzedek, as is well known, discusses this in his responsa, siman Tzach. It is a pity people do not cite this Tzemach Tzedek, because what he says makes a great deal of sense. He says that the case under discussion is like meat roasted over a fire. Certainly that is a solid piece. For example, if we take a pot that is a kli rishon off the fire and put it on a table, then move it to another table and to ten more tables, it certainly remains a kli rishon. A kli rishon removed from the fire is a kli rishon in every respect, and it cooks under Torah law. At least, that is the view of the Bavli and the Shulchan Aruch. The Yerushalmi and the Ramban are exceptions who ruled otherwise. But a kli rishon removed from the fire remains a kli rishon. So certainly, meat roasted over a fire and exposed directly to the fire is itself a pot

1:11:38 Speaker 2 The meat is the pot. So if they moved the steak across this table, to another table, to another place, it is considered like a kli rishon, a vessel directly heated on the fire. So when the Magen Avraham writes that this is a problem, he means it cooks on Shabbos. No, no—you shouldn’t put uncooked onion on it, or things like that. That is because even someone who does not accept the principle of davar gush, a solid hot food, could say there is a problem here. According to the very logical explanation of the Tzemach Tzedek of the Alter Rebbe’s position, whether he accepts davar gush is a dispute among the rabbis about how to understand the Kuntres Acharon at the beginning of subsection 11. As you know, we won’t get into that. But regarding Pesach, the Alter Rebbe cites the stringency of the Chok Yaakov: if you occasionally put hot pizza, hot bourekas, chametz, on the countertop, then it requires pouring boiling water over it and also an even meluben, a heated stone. A heated stone means taking a stone that has been on the fire for a long time and picking it up with tongs, right? And then—there are several ways to do it, but one way is to pour hot water and then move the stone over the water so that it boils again. Because once the poured water touches the surface, it is only considered water poured from a kli rishon; this makes it an actual kli rishon. Strictly speaking, you would have to take the entire countertop and put it into a kli rishon. So if we can’t bring the countertop to the kli rishon, we bring the kli rishon to the countertop. How? With the heated stone. Today there is a suggestion to use an iron, sometimes an old one, heat it until it reaches a high temperature, and then, when you pour the water, use the iron. Once it is very hot, you can unplug it so that we don’t take

1:13:25 Speaker 2 any risk, and simply move it over every place where the water was poured. You actually have to go over the entire vessel, or the entire surface. Now, regarding the sink, we nevertheless have a custom today to cover it, and there are reasons for that. First, not all opinions consider pouring boiling water together with a heated stone to be a method that fully kashers it, equivalent to a kli rishon. Not according to all opinions. There is also—sorry—sometimes a problem with cracks in the countertop. So, fine, people use harsh chemicals, various kinds of bleach, to clean it. Some even put a little plaster over it to cover it, but often there is concern that it was not kashered properly. So they put on a covering, such as thick aluminum that will not tear. Because the Alter Rebbe introduces a very significant point. We know that if a meat pot used to cook meat and a pot used to cook milk—even a non-kosher pot and a kosher one—touch each other, with the two pots touching on the outside, then after the fact they do not become forbidden. Why? Because one vessel does not render another vessel forbidden without liquid between them. This is a very well-known principle in section 92 of Yoreh De’ah, and it appears again in the Shach’s discussion of mixtures in section 105. A very well-known principle. So here too, the Alter Rebbe discusses an oven in which people sometimes baked. In those days, they would sometimes bake chametz directly on the oven. And when they baked directly on it, lighting the oven did not make its top hot enough for sparks to fly from it, whereas what is needed here is actual libun chamur, intense heating. So one option, says the Alter Rebbe, is to take a sheet of iron and make use of this principle that one vessel does not render another forbidden without liquid between them. The sheet creates a barrier over the oven. So even if chametz had been absorbed into the top of

1:15:30 Speaker 2 the oven, it cannot pass into the sheet of iron placed over it. Of course, anyone who has studied the discussion in section 92, paragraph 8, about one vessel not rendering another forbidden without liquid between them knows that we do not rely on this initially. The Rema implies that this rule applies only after the fact, and initially we are concerned about it. But one reason is that this area is used frequently. If we start placing pots directly on a spot that is completely dry, sometimes it won’t be completely dry; sometimes it will be wet, and then we won’t be able to say that one vessel does not render another forbidden without liquid between them. With a little moisture, there is already a broad dispute about whether—there are arguments that it does not count as moisture and is still considered dry, but sometimes there may be more than that. So that is why the rule is not to do this initially. That is how many have explained it. But it is not simple to rely on this initially. Here, though, it is different. That is why the Alter Rebbe writes that you take something you will not use on Pesach. In other words, you place it over the oven and leave it there, so there is no concern that you will remove it and one time put a pot directly on the top of the oven without it. So in a case where you put that in place—and this will be a leniency we will use for many things in the next class, many things; it will help us a great deal. So let’s go back to the sink—to the countertop, sorry. Once we have poured hot water over the countertop, there is no need to use a heated stone as well, because we cover it. The Alter Rebbe discusses something more serious than this: an oven that was not kashered at all, with a sheet of iron placed over it. So here, if you put on something thick, that, together with the boiling water poured over it,

1:17:22 Speaker 2 is perfectly fine. How do we actually do it—let’s finish with this surface—how do we kasher it? We’ll continue in the next class. I wanted to fit everything into this class, but it is already long. In the next class we’ll talk directly about all the utensils we encounter in our kitchens. Just to finish this point: how, in practical terms, do we kasher our countertop? We take a vessel that is not a chametz vessel. The Alter Rebbe is stringent about this in section 452: it should be either a kashered vessel or a new one. You can take a new kettle and fill it. Once the water comes to a boil, we make sure, of course, that the entire countertop is very, very clean and very, very dry. If we pour hot water onto water, that will weaken the effect of the hot water; it will cool it down. So we make sure of that, and then we pour from place to place. With one kettle, for example, you can do one area and then another. You go back and forth like this, pouring the water. Some also pour cold water onto the countertop, because the Shulchan Aruch says—this is learned from Tractate Zevachim regarding consecrated offerings—that each time you pour hot water, you should pour cold water afterward. One reason is the concern that the water will be reabsorbed, and the absorbed taste will go back in. True, today we are stringent that the surface should not have been used for hot chametz within the past twenty-four hours, but the practice is nevertheless to pour cold water immediately. That is why, when kashering a vessel, you put it into hot water and then into cold water. But a large surface is no longer a vessel. So although this was stated regarding a vessel, some say that nowadays, when you pour water onto a countertop, it cools down within mere seconds. Since it cools down within seconds, there is not so much need

1:19:06 Speaker 2 to worry about pouring cold water. But some still do it. It is written in the Shulchan Aruch that after kashering with heat, you use cold water. This is the preferred practice, not a requirement that would invalidate the kashering. Now, if, for example, we have done this section, then when we pour onto it, some water will naturally run over to the next section. So if I now boil more water in the kettle and pour it over the new area that I haven’t done yet, it is wet there. So you need towels. First, you can take a squeegee and clear away the water, and then dry it. Every area you kasher must be both clean and completely dry. Another important thing I didn’t mention: the countertop should not have been used for twenty-four hours beforehand—at least, not for anything hot. No hot chametz should have been absorbed into it during the twenty-four hours before kashering. As we said, whenever we kasher through hagalah, immersion in boiling water—when we do libun chamur, intense heating, that is different. Even libun kal, lighter heating, can be done when the item has been used within the past twenty-four hours. But hagalah of an item used within the past twenty-four hours is another matter. So after twenty-four hours, you pour hot water, and anyone who wants can also pour cold water. You make sure to dry the next area completely and then move on. With about four kettles of water, you can sometimes easily finish the entire countertop. It depends; some homes are larger and sometimes need more. That is how we deal with the countertop. Afterward, it needs to be covered. Now, when kashering it, there are also tiles along the front—at the back of the kitchen counter—that rise a little way up, to keep the pots from dirtying the wall. Sometimes the Pesach pots touch them, so you certainly pour hot water there too. Alternatively, sometimes it

1:20:58 Speaker 2 Ceramic, so we’ve discussed how it really can’t be kashered. But at least it should have a thick covering that won’t tear. Some opinions say that, as an added stringency, it’s best not to place hot pots directly on the covering either. After all, regarding an oven, we said in section 65 that you can put in a shelf, and that serves as a barrier. Here, too, there’s a barrier: thick aluminum foil, or another thick material used as a covering. But when you put a hot pot on it, since the covering isn’t all that thick, the surface underneath can sometimes heat up. And since the kashering isn’t one hundred percent effective, and some water may have gotten between the surfaces, there’s a concern. It would be very difficult for taste to pass from the countertop to the aluminum and then from the aluminum to the pot, but there is still such a stringency. I once heard from Rabbi Ashkenazi a"h that if someone doesn’t have a thick covering, then when putting down pots, they should place something underneath them—a folded towel, for example. Sometimes people buy a thick wooden trivet and put the pots on that, so they aren’t placing hot things directly on the covering. Because, ultimately, the kashering done underneath isn’t the most reliable kind.