10 – The Principles of Hagalat Kelim

1. When Does Taste Absorbed into Utensils Render Their Contents Forbidden?

Though the walls of pots and other vessels appear solid and impervious, they actually absorb the taste of food cooked in them. Thus, if one cooks non-kosher meat in a pot, its flavor gets absorbed into the pot’s walls, and kosher meat subsequently cooked in the same pot becomes forbidden, as the non-kosher taste absorbed in the walls is released and absorbed by the meat.[1]

However, there is a principle that anything which contributes foul taste (”noten ta’am li-fgam”) does not cause other foods to become forbidden. For example, if a bit of foul-tasting non-kosher meat falls into some kosher meat, the meat may be eaten since the non-kosher taste is foul. The same applies to tastes absorbed by vessels. Moreover, the rule is that any taste absorbed by a vessel becomes foul after twenty-four hours. Therefore, if non-kosher meat is cooked in a pot, and twenty-four hours later kosher food is cooked in the same pot, the latter dish remains kosher because the taste in the pot is foul, and foul taste does not render food forbidden (SA YD 103:5).

However, it is forbidden le-khatĥila to use a pot that has absorbed non-kosher taste, even after twenty-four hours have elapsed, because the Sages were concerned that one would forget and inadvertently cook in it before twenty-four hours have elapsed. They therefore ruled that since such a pot is forbidden to begin with, it may not be used until koshered (SA 122:2). Be-di’avad, if one forgot that the pot absorbed the taste of forbidden food and cooked another food in it, if twenty-four hours passed from the time the non-kosher food was cooked, the food in question remains kosher. But if one knows that a pot had absorbed a non-kosher taste, but cooks kosher food in it anyway, the Sages penalized him by prohibiting this dish for him and his family, even though the non-kosher taste in it had already turned foul.[2]

[1]. It is impossible to measure how much taste the walls of a pot absorb and how much they release back into the food; some vessels absorb more than others do, and some tastes are more easily absorbed than others. Since this is a persistent uncertainty with no means of resolution, the Sages determined that one should consider the entire wall of the pot to be completely filled with the taste of whatever is cooked inside of it. Thus, if one cooked non-kosher meat in a pot and then cooked kosher meat in the same pot, we assume that the walls of the pot absorbed taste from the non-kosher meat and subsequently discharged the taste back into the kosher meat. And since our pots and utensils do not hold sixty times the amount that can be absorbed into the walls of the pot, anything that was cooked in a pot that had previously absorbed the taste of a prohibited food becomes prohibited. Even if one cooked another piece of kosher meat afterward, it too would become prohibited, since perhaps not all of the absorbed forbidden taste was released during the first usage and was released during the second usage. In sum: in the case of a perpetual uncertainty where it is impossible to determine absolutely how much taste was absorbed and how much was released, we are stringent.

[2]. Most poskim maintain that if one intentionally cooked in a pot that required hagala, the Sages penalize him by forbidding the food for him and those for whom he cooked it (Knesset Ha-gedola YD §122; Hagahot Ha-Tur §26; Darkhei Teshuva YD 122:5; Yabi’a Omer YD 8:14; and Hagalat Kelim Le-Pesaĥ, second introduction, p. 17).

2. Ĥametz Utensils on Pesaĥ

Vessels used throughout the year with hot ĥametz foods cannot be used during Pesaĥ since heat causes vessels to absorb the taste of ĥametz. In order to use such utensils during Pesaĥ, one must first remove the taste of the ĥametz through hagala or libun.

If one cooks in such a pot on Pesaĥ knowing that it had not been koshered, even if twenty-four hours have passed and the taste of the ĥametz has been befouled, the cooked food is forbidden. As we have learned, the Sages forbade such food in order to penalize people who deliberately cook in vessels that have absorbed ĥametz and have not been koshered.

What if one errs and cooks in a pot that was not koshered for Pesaĥ? According to Shulĥan Arukh, if twenty-four hours have elapsed since the ĥametz was cooked in the pot, the food may be eaten on Pesaĥ, because the taste of the released ĥametz is foul. According to Rema, the food is forbidden even though the ĥametz is foul because the prohibition of ĥametz is especially severe, for even a drop of ĥametz causes a food to be forbidden (SA 447:10; see above 7:5).

Ĥametz utensils that one does not wish to make kosher for Pesaĥ must be cleansed of any residual ĥametz and put away in a closed place so that nobody inadvertently uses them during Pesaĥ (SA 451:1; see also above 6:4, where we learned that such utensils should not be sold).

3. Releasing through the Same Method as Absorption (“Ke-bole’o Kakh Polto”): Hagala and Heavy Libun

The most basic principle of koshering cooking utensils is that forbidden taste is released from the vessel in the same manner that it was absorbed: “ke-bole’o kakh polto.” There are two principal media through which utensils absorb taste: boiling liquid and direct flame.

If a pot absorbs a forbidden food through a process of boiling – for example, if it was used to cook ĥametz food like pasta or porridge – the pot is made kosher for Pesaĥ by immersing it in boiling water, which causes the ĥametz taste to be released. The same applies to ladles and serving spoons: when used with ĥametz foods hotter than yad soledet bo (hot enough to cause the hand to recoil), they absorb the taste of the ĥametz and must be koshered through immersion in boiling water.

However, if a vessel absorbs ĥametz through direct heat of fire, without a liquid medium – such as in the case of a cake baked on a tray, dough baked on skewers, or jachnun or kugel baked in a pot – it is koshered by means of heavy libun, that is, heating the vessel by fire until it gives off sparks or becomes red hot.

Absorption through a liquid medium is relatively mild, so boiling hot water is sufficient to extract the taste of the ĥametz from the utensil. Absorption into a tray or skewer is more intense, as the heat of the fire causes the taste of the food to be absorbed deep into the very particles of the utensil. Boiling water is insufficient to remove all of the absorbed taste, and such utensils must be koshered by the same means that they absorbed – by fire. This is “heavy libun,” in which the fire incinerates the taste that had been absorbed in the utensil.

To highlight the difference – hagala extracts the taste absorbed in the vessel, while libun incinerates it in situ.

Therefore, before undergoing hagala, a vessel must be cleaned of any residual food, because hagala releases the taste absorbed into a utensil but does not destroy the residual food stuck to it.  There is no need, however, to clean a utensil before libun, because any food that remains will be completely incinerated in the libun process.

4. Defining the Difference between Absorption through Liquid and Absorption through Fire: the Status of a Frying Pan

Even when a baking tray is coated with oil to prevent sticking, the absorption that occurs during the cooking process is considered to be by means of fire, thus requiring heavy libun to render it kosher. Only when the oil at the bottom of the vessel sizzles and bubbles is the absorption considered to be by means of a liquid.[3]

In light of this, most Rishonim maintain that a frying pan can be koshered through hagala (Rosh, Raavya). Even if the oil is used up and the food burns, hagala is sufficient since there was oil present at the beginning of the frying process, and the taste of the food absorbed into the pan was by means of the oil, i.e., the milder form of absorption. The same applies to a pot in which a non-kosher food was cooked: the pot can be koshered by hagala even if the food dries up and burns (MB 451:63; Kaf Ha-ĥayim ad loc. 137).

However, several leading Rishonim maintain that a frying pan has the status of a baking tray and must be koshered via heavy libun, because people often fry with small amounts of oil, and the oil is often used up, causing the taste of the food to be absorbed via fire (Rashba). Although there is agreement that a pot can be koshered through hagala even if the food dries up and burns, there is reason to be more stringent about frying pans because only a small amount of oil is used from the outset, and it often gets used up.

In practice, frying pans should ideally be koshered via light libun (as will be explained in the next section), although if twenty-four hours have passed since the frying of the forbidden food, hagala is sufficient be-di’avad.[4]

A Teflon or “non-stick” frying pan, in which food is fried without oil, cannot be koshered for Pesaĥ. In theory it is possible to kosher it via heavy libun like a baking tray, but as a practical matter this will damage the pan (as will be explained below, section 7).

A frying pan used primarily for making malawach, which is baked and heated without sizzling oil, must be koshered by heavy libun since the absorption takes place via fire. But a pan generally used for other things and infrequently used for malawach may, in extenuating circumstances, be koshered via hagala, in accordance with its primary usage (as will be explained below, section 9).

[3]. This is according to Pri Ĥadash 451:1, quoted by SAH 451:36 as saying: “Since the dough is not sizzling with oil or fat, it means that fire alone causes the ĥametz to be absorbed.” Kaf Ha-ĥayim ad loc. 139 cites them, and this is the ruling of Yeĥaveh Da’at 1:7 (although Kaf Ha-ĥayim 451:76 states that if there was enough liquid present in the pot to wet something that touched something that was in the pot (“tofei’aĥ al menat le-hatfi’aĥ”), the pot can be koshered by hagala; this requires further investigation). Accordingly, a utensil used to cook jachnun or kugel is considered to have absorbed by means of fire, since there is no sizzling liquid (see Hagalat Kelim Le-Pesaĥ 5:23 and the supplementary material ad loc.). If a pot is generally used to cook through a liquid medium but less frequently used to make jachnun or kugel, it may be koshered by hagala in extenuating circumstances, as will be explained below in section 9.

[4]. BHL 451:11 concludes that most poskim maintain that one may kosher a frying pan via hagala, and I have already mentioned the leading Rishonim on this topic. SA YD 121:4 rules that a frying pan generally requires libun to be koshered from forbidden foods, but for Pesaĥ hagala is sufficient. Many Aĥaronim (Gra and Shakh ad loc.) explain that regarding Pesaĥ R. Karo combines the opinion that hagala is sufficient with the view that ĥametz before Pesaĥ is considered permissible, and thus rules leniently that one may kosher a frying pan for Pesaĥ via hagala. Rema agrees in principle but states that light libun is the proper method le-khatĥila. Later Aĥaronim also disagree about this issue: Pri Ĥadash and R. Ĥayim ibn Attar require libun since ĥametz is considered a forbidden substance even before Pesaĥ, while SAH permits using hagala even le-khatĥila. See Hagalat Kelim Le-Pesaĥ 13:202.

I have written that the preferable method for koshering a frying pan is light libun, and although apparently light libun is ineffective according to those who require heavy libun, there are in fact those who maintain that light libun is as effective as heavy libun (this may be the opinion of R. Avigdor, quoted in the Hagahot Maimoniyot). Additionally, some authorities explain that the principle of ke-bole’o kakh polto also applies to the temperature of the libun, as will be explained in the next section. Consequently, light libun is sufficient, since it takes place at least at the same temperature as the initial absorption. On the other hand, it is better to use light libun since sometimes there are small grooves or cracks in the pan which are difficult to clean, in which case even those who maintain that hagala is enough to kosher a frying pan would require libun to eradicate the residue in the cracks. However, one may rely, be-di’avad, on the majority of poskim who maintain that one may kosher a frying pan via hagala, especially since once twenty-four hours have elapsed since its last use, any uncertainty pertains to a rabbinic prohibition.

5. Heavy and Light Libun: Does Temperature Affect Absorption?

Heavy libun means heating a utensil by fire until any ĥametz taste in it is incinerated. One indication that libun has taken place is that the utensil undergoing libun becomes so hot that sparks fly from it when it is brought into contact with iron. Another indication is that its outer layer peels off, or that it becomes red hot.

Light libun means heating a utensil by fire to the point that a piece of straw or thread placed on the opposite side of the utensil becomes blackened from the heat. For example, to kosher a frying pan through light libun one must place the pan over fire and then put a piece of paper on the frying surface. When the paper starts to become scorched, the pan has been koshered.

Light libun is not effective where heavy libun is required, because the objective of libun is to incinerate any taste absorbed into the utensil, and this is only achieved through heavy libun. However, light libun is more effective than hagala because it is more capable than hagala at extracting the taste of ĥametz from the utensil, and apparently it can also incinerate some of the absorbed taste. Sometimes, when it is uncertain if libun is necessary, one may suffice with light libun. Light libun has another advantage as well: if a utensil has crevices that are difficult to clean, hagala cannot kosher it, since hagala removes the taste absorbed into a utensil but cannot render kosher the residual food stuck in its grooves. However, if one performs light libun and aims the fire at the grooves, the residual food will be incinerated, and the utensil will be rendered kosher. Light libun can be performed by putting a utensil in an oven and heating it at the highest temperature for about half an hour.

It is worth noting, however, that some poskim rule leniently that a utensil that has absorbed ĥametz via fire does not necessarily require heavy libun. In their opinion, the principle of ke-bole’o kakh polto applies to the temperature at the time of absorption. Thus, if a utensil absorbed the taste of forbidden food at a temperature of 300ºC, it can be koshered at the same temperature, and if the absorption occurred at 200ºC, it can be koshered at 200ºC, even though it does not become red hot or give off sparks at this temperature. According to these authorities, a cooking tray that absorbed a forbidden taste in an oven can be koshered in that oven at the same temperature as the absorption. The practical halakha follows the majority opinion, namely, that a vessel that absorbed taste via fire and reached a temperature beyond yad soledet must be koshered by heavy libun. However, in extenuating circumstances and when there are other reasons to be lenient, we take the lenient opinion into consideration.[5]

It should be emphasized that absorption through fire can only happen while the food is being cooked by the fire on the flame. For example, if one cuts a baked good while it is on the burner, the knife absorbs the taste of the food through fire. However, if the baked goods were first taken off the fire and then cut, even if the baked goods are dry, the absorption is considered mild, and the knife may be koshered through hagala.

[5]. The laws of light and heavy libun are discussed in SA and Rema 451:4 and in MB ad loc. (see R. Pfeiffer’s Kitzur SA, Basar Be-ĥalav vol. 2 ch. 12, and explanation 3 regarding the laws of light libun). However, it seems that according to R. Avigdor, cited in Hagahot Maimoniyot on MT, Laws of Forbidden Foods 17:5, light libun works just as well as heavy libun, but other poskim disagree. See Hagalat Kelim ch. 5 n. 3 that according to the accurate version of Hagahot Maimoniyot, even R. Avigdor agrees that light libun does not work like heavy libun.SAH 451:16 and 19 states that in order to render the crevices in the frying pan kosher, one must aim the flame at them. See also Taz 451:8, which states that light libun causes the other side of the pan to reach the temperature of yad soledet bo, and see Piskei Teshuvot 451:18. The halakha does not follow this view; rather, light libun is when the pan reaches the temperature that would scorch a piece of straw on the other side of the pan, as Rema 451:4, MB 31 ad loc., and other Aĥaronim explain.

According to most poskim, a utensil that absorbed taste by fire requires heavy libun, even if the utensil itself only reached yad soledet bo. However, there are authorities who are lenient, as noted above. See Arugot Ha-bosem §119 and Minĥat Yitzĥak 3:66. See also Kitzur SA op. cit. explanation 5 and Piskei Teshuvot 451:17.

6. Koshering Vessels That Absorbed Ĥametz Prior to the Onset of the Prohibition

We have learned that if a utensil absorbs a forbidden food by means of fire, it must be koshered by fire. It is important to note that this principle applies only when non-kosher food has been absorbed. For example, if one roasts non-kosher meat on a skewer, the skewer must be koshered through libun, because the non-kosher food was absorbed by means of fire. However, if at the time of absorption the meat was kosher, and only later became non-kosher, the utensil may be koshered through hagala. To use a classic example, if a korban (Temple offering) was roasted on a skewer, and the meat of the korban later becomes notar (the sacrificial meat left over when the time to eat the korban ends, which must be incinerated and not eaten), the taste absorbed by the skewer is also notar and thus forbidden. The skewer may not be used until it has been koshered, but it is not necessary to perform libun. Hagala is sufficient because the skewer absorbed the taste of the meat while it was still permitted for consumption.[6]

Accordingly, if one mistakenly baked meat and then dairy (or vice versa) in the same tray, the status of the tray depends on whether twenty-four hours elapsed between the baking of meat and dairy. If less than twenty-four hours elapsed, the baked food is forbidden because the flavor of meat mixed with the dairy food. The tray also absorbed forbidden taste, and thus heavy libun is required to kosher it. But if twenty-four hours elapsed, the taste of the meat became foul, and thus the dairy food may be eaten. Moreover, although the Sages rule that the tray must be koshered, hagala is sufficient, because it did not absorb any forbidden taste. In practice, since people are accustomed to putting such trays in the oven, the best thing is to kosher it through light libun, i.e., by putting it in the oven at the highest temperature for half an hour, for we have already seen that light libun is more effective than hagala.[7]

The leading Rishonim disagree about whether the absorption of ĥametz during the year is considered the absorption of permissible matter, in which case baking trays can be koshered for Pesaĥ by means of hagala, or the absorption of forbidden matter. According to most poskim and SA 551:4, ĥametz has the status of forbidden food even though it is completely permissible throughout the year, since vis-à-vis Pesaĥ ĥametz is always considered forbidden and even before Pesaĥ it bears the name “ĥametz.” According to this opinion, baking trays must be koshered via heavy libun. However, in extenuating circumstances and where there are other reasons to be lenient, the lenient position is occasionally relied upon (MB 451:28).[8]

[6]. The basis for the distinction between utensils that absorbed permissible matter (heteira bala) and those that absorbed forbidden matter (isura bala) is explained in AZ 86a. The idea is that hagala releases most of the taste that is absorbed in the utensil. Thus, if the utensil absorbed forbidden taste, all of the taste must be eliminated from the utensil since the utensil became subject to a presumption (ĥazaka) of being forbidden. On the other hand, when the taste absorbed in the utensil was permitted at the time of absorption, there is no need to extract the weakened taste that remains after hagala. This distinction was subject to the discretion of the Sages since, after twenty-four hours, the taste absorbed in the walls of the utensil befouls the food instead of improving it and must only be extracted due to rabbinic injunction. Therefore, the Sages did not require this extraction when permissible taste was absorbed. According to this, we may only be lenient in a case of heteira bala once twenty-four hours have elapsed since the utensil absorbed the permitted taste. See also R. Pfeiffer’s Kitzur SA, Basar Be-ĥalav vol. 2 explanation 9 for an examination of other explanations.

[7]. This law is explained very well in R. Pfeiffer’s Kitzur SA, Basar Be-ĥalav vol. 2, ch. 2, based on Responsa Rama Mi-Fano §96 and Ĥatam Sofer YD §110. See also Kaf Ha-ĥayim 451:70, which lists the opinions and tended toward requiring light libun if it would not ruin the utensil, even though many authorities rule leniently that hagala is sufficient. See Kitzur SA (op. cit. ch. 12 nn. 7 and 10) for a discussion of the possibility of performing light libun in a pastry oven. It also seems that we can be lenient and allow light libun in an oven by factoring in the opinion that ke-bole’o kakh polto is a function of temperature, and the fact that the oven becomes an uncertainty about a rabbinic law after twenty-four hours. Thus, light libun koshers an oven even le-khatĥila.

[8]. See Hagalat Kelim, 7th introduction, which lists the opinions of the Rishonim in detail. Among the stringent opinions are: Rif, Rosh, Ran, and Rashba. Among the lenient opinions: Rambam, Rabbeinu Tam, and Or Zaru’a.

7. Utensils Likely to Be Damaged by Libun; Baking Trays

As we have learned, the objective of libun is to incinerate all taste absorbed into a utensil. To that end, the utensil must be heated to a very high temperature (more than 300ºC). There are two ways to tell that a vessel has reached such a temperature. One is that the utensil undergoing libun becomes so hot that sparks fly from it when it is brought into contact with iron. The other indication is that its outer layer peels off, or that it reddens completely.

However, some utensils are likely to be damaged by this process. It is forbidden to kosher such utensils through libun because we are concerned that, in an attempt to protect his utensil from damage, the owner will not perform libun properly. For example, it is forbidden to kosher an earthenware vessel that has absorbed non-kosher food or ĥametz, because libun is liable to crack the vessel. Nor is hagala effective on earthenware vessels because their unique composition causes them to absorb taste but not sufficiently release it. The only way to kosher an earthenware vessel is to return it to the kiln, where it is impossible to protect it from the full force of the kiln’s furnace. As a result, the vessel will either break and be lost or survive and be kosher (SA 451:1; MB ad loc. 13, 14).

Wonder Pots (an Israeli invention used for baking on stovetops) absorb taste though fire and therefore require heavy libun. However, since they are made of aluminum they cannot endure the libun process, and hence there is no way to kosher them for Pesaĥ (although if it was used to bake only simple cakes, one may be lenient and kosher it by means of hagala, as explained above in section 4).

Baking trays designed for domestic ovens become severely damaged by heavy libun. They lose their pleasant appearance and become warped to the extent that most people would no longer consider them usable. Therefore, they cannot be koshered through libun. There are, however, industrial baking trays that do not become seriously damaged by fire, and it is permissible to perform libun on such trays for Pesaĥ.

It is possible that one who knows that he will not care if his tray becomes warped and unattractive would be permitted, in time of need, to perform libun on such a tray. After all, every time libun is performed there is a risk of some damage, and the Sages only forbade libun where there is concern that the utensil will be completely ruined. When one will not be distraught if his baking tray is damaged, he may kosher it via libun. In practice, though, one should ask a competent authority what to do in this case.[9]

[9]Pri Megadim explains (Mishbetzot Zahav §452) that one may perform libun on a utensil that might become partially damaged. Sidur Pesaĥ Ke-hilkhato 8:40 and Hagalat Kelim 5:6 and 13:315 state that one should not kosher baking trays using libun. Although it is possible to use baking trays that have undergone libun, most people nowadays prefer to throw them out. The question is whether the law is different for one who is unfazed by a warped baking tray (as per Pri Megadim). Perhaps someone whose baking tray became non-kosher – meaning that unless he koshers it he will have to throw it out anyway – may perform libun on it, for if he does not like the way it looks afterward he will simply throw it out. Some authorities rule leniently in this regard, but I am inclined to be stringent unless it is absolutely necessary. In extenuating circumstances, perhaps one may rely on Arugot Ha-bosem, cited in n. 5.

8. The Principles of Hagala

As we have learned, a pot absorbs the taste of the foods cooked in it. Cooking has the capacity to mix the tastes of different foods with one another, and just as cooking can cause the taste of meat to be absorbed by potatoes cooked with it, so too it can cause the taste of a food to be absorbed in the walls of the pot in which it is cooked.

There are, however, different levels of intensity in cooking, and the operative principle is ke-bole’o kakh polto. Thus, if the absorption is caused by intense cooking, the koshering process must be equally intense. However, if the cooked food never reaches the temperature of yad soledet (45ºC according to the opinion that sets yad soledet at the lowest temperature), there is no reason to be concerned about absorption, and it is not necessary to perform hagala to kosher the utensil.

The levels of koshering are as follows:

A kli rishon on the flame: The most intense form of cooking is that of a kli rishon (the vessel in which the food is cooked) on a flame, where the fire heats the mixture of food continuously, causing its different tastes to be absorbed into each other and by the walls of the pot. Ke-bole’o kakh polto: In order to kosher such a vessel, one must immerse it into the boiling water of a kli rishon on a flame. It must be emphasized that even if the water in the pot was not boiling when the non-kosher food or ĥametz was absorbed, it must boil during hagala, because the principle of ke-bole’o kakh polto relates only to the type of absorption – kli rishon or kli sheni – but whenever dealing with absorption in a kli rishon on the burner, the koshering must be carried out with boiling water.

A kli rishon removed from the flame: This refers to a vessel that was heated over a flame and then removed, or the flame was extinguished. Such a vessel still has the capacity to cook, and food placed in it will become slightly cooked from the lingering heat from the fire. Nevertheless, the heat continuously dissipates, as does its capacity to cook.  Therefore, it need not be koshered in a pot of boiling water on a flame; it is sufficient to place it in a kli rishon that is no longer on a flame.

Liquid poured (“irui”) from a kli rishon: This has the capacity to cook the surface layer (“kedei klipa”) of a food item. For example, if ĥametz soup was poured into a bowl from a kli rishon, the taste of ĥametz will be absorbed by the surface layer of the bowl but will not penetrate its entire width. To kosher such a bowl, it is sufficient to pour boiling water over it from a kli rishon.

A kli sheni: This refers to hot food that was first cooked in a vessel over fire and then transferred to a different one. The poskim disagree about whether such a food can cause its taste to be absorbed into the surface layer of other foods or utensils. For example, if one places a spoon in a kli sheni, some poskim say it will not absorb the taste of the food in the vessel, and others say it will. Regarding all other forbidden foods, SA (YD 105:2) rules that although, according to the prevailing opinion, hagala is not required, it is nonetheless proper to do so le-khatĥila. Regarding Pesaĥ, however, SA (451:5) rules that hagala is required. Due to the severity of the ĥametz prohibition, the lenient position is not even mentioned (Kaf Ha-ĥayim ad loc. 20).

Some are even stringent regarding a kli shlishi and beyond, that is, utensils at least twice removed from the vessel in which the food was cooked, maintaining that as long as a food remains at the temperature of yad soledet, a vessel will absorb its taste and must be koshered – ke-bole’o kakh polto. However, most poskim are lenient in this respect. Nevertheless, because of the gravity of the ĥametz prohibition, it is customarily preferable to be strict about koshering any vessel that contained ĥametz at the temperature of yad soledet.[10]

[10]. A kli rishon on the flame must always be koshered in boiling water. Whether its temperature was just barely yad soledet or beyond the boiling point at the time of the absorption, all absorption in a utensil on the fire is treated uniformly and the utensil must always be koshered in boiling water. This principle is explained beautifully in R. Pfeiffer’s Kitzur SA, Basar Be-ĥalav vol. 2. However, some authorities maintain that even a utensil sitting on the fire is subject to the standard principle of ke-bole’o kakh polto, meaning that if it absorbed taste at 80ºC it releases the taste at the same temperature. See Sidur Pesaĥ Ke-hilkhato 1:4, SAH 451, and Kaf Ha-ĥayim ad loc. 82.

Regarding a kli rishon not on the flame, most poskim agree that the koshering process must be done at a temperature of yad soledet bo, as stated in MA  451:7, Pri Ĥadash 452:3, and Pri Megadim 451 (Mishbetzot Zahav 9). However, Sidur Pesaĥ Ke-hilkhato 1:4 mentions opinions that the koshering temperature must be the same as the absorption temperature, so to avoid uncertainty it is best to kosher such a utensil in boiling water. The temperature of yad soledet is uncertain, somewhere between 45ºC and 71ºC (see Peninei Halakha: Shabbat 1:10:7), so to kosher a utensil, the water must be at least 71ºC. On the other hand, if the utensil was used at a temperature of at least 45ºC, there is concern that absorption took place and therefore one should be stringent.

Most poskim maintain that a kli sheini does not absorb, but due to the stringent nature of the prohibition of ĥametz, they mandated hagala. Be-di’avad, if the utensil was not koshered and was later inserted into hot food, the food is not forbidden (MB 451:11). The vast majority of poskim maintain that a kli shlishi does not absorb at all. Even so, several authorities insist that every utensil, even ten times removed from the fire, must be koshered if its contents reached the temperature of yad soledet (Pri Ĥadash). See Hagalat Kelim 5:52. This is the le-khatĥila practice.

We should also note that the poskim disagree about the status of a solid food (“davar gush”) at the temperature of yad soledet: According to Rabbeinu Yona, Me’iri, Maharshal, Shakh, and MA, even if it is in a kli shlishi, the food has the status of a kli rishon removed from the flame, since it retains its heat. Conversely, according to Tosafot, Ran, Rema, and Gra, the food assumes the status of the utensil that contains it. Regarding hagala, the custom is to kosher such utensils in boiling water on the fire.

9. What Determines the Type of Hagala: Main Use or Most Intense Absorption?

According to SA (451:6), if a utensil was sometimes used as a kli rishon and other times as kli sheni it is koshered based on majority usage. Thus, if it was used primarily as a kli sheni, it can be koshered like a kli sheni. Likewise, if it was sometimes used in fire, but primarily used as a kli rishon, it may be koshered in a kli rishon. And if it was sometimes used as a kli rishon, but primarily used cold, it can be koshered in cold water. According to Rema, on the other hand, the utensil must be koshered based upon its most intense usage, not according to its predominant use.

To illustrate, if a particular spoon is usually used to eat soup from a kli sheni, and occasionally used to stir food in a pot on the fire, Shulĥan Arukh maintains that it is koshered based on its primary usage, which in this case would mean hagala in a kli sheni, whereas according to Rema it must be koshered via hagala in a kli rishon, in keeping with its more intense form of absorption.

Rema’s rationale is that once the utensil has absorbed the taste of foods in a more intense fashion, the only way to remove what has been absorbed is by koshering the utensil with the same intensity. Shulĥan Arukh’s opinion is based upon the presumption that the koshering of the utensil takes place more than twenty-four hours after its last use, at which point the absorbed taste is foul. According to the Torah, such a utensil does not require hagala. The Sages, however, required that any utensil that has absorbed the taste of forbidden food be koshered, out of concern that if they were to permit the use of such utensils after twenty-four hours had elapsed, people might misjudge the time and inadvertently treat leniently utensils that had been used in the past twenty-four hours. But the Sages required that such utensils be koshered according to their common use, and not their most intense use.

In practice, the custom le-khatĥila is to be stringent and to kosher every utensil according to its most intense usage. Furthermore, even if a utensil’s most intense usage was irui, the custom today is to kosher all utensils in a kli rishon on a flame, in order to avoid a situation in which one has forgotten that a utensil was in fact used as a kli rishon on a flame. However, in extenuating circumstances, one may be lenient and kosher a utensil according to its primary use (MB 451:47; Kaf Ha-ĥayim ad loc. 100).

If a utensil was used primarily as a kli rishon and occasionally on the fire, even Rema allows koshering via light libun (MB ad loc. 48). If there is a concern that even light libun will damage the utensil, it is considered a be-di’avad situation, and one may kosher it in a kli rishon, in accordance with its primary use (Kaf Ha-ĥayim ad loc. 108).[11]

[11]. Among the authorities who rule leniently and allow one to kosher utensils based on main usage: Rif, Rambam, Ran, and Rashba. The authorities who require koshering based on the most intense usage are: She’iltot, Rashi, Tosafot, and Raavya. These groups disagree about ĥametz as well as other prohibitions. There is another reason to be stringent regarding ĥametz alone: According to Rema 447:10, even ĥametz that contributes foul taste (noten ta’am li-fgam) renders other foods forbidden; therefore, one must perform the most intense form of hagala on such a pot. On the other hand, regarding absorption that takes place due to fire, there is a reason to be lenient, namely, there is an opinion that a pot that absorbs ĥametz before Pesaĥ is considered to have absorbed permissible matter (heteira bala). We calculate majority and minority usage based on use with ĥametz that requires koshering; in other words, a utensil that is primarily used for cold permitted food and was used once for hot ĥametz must undergo hagala in boiling water. However, if most of the ĥametz usage was cold, as in the case of a table or countertop, it can be cleaned with cold water according to SA, even though it was occasionally used with hot ĥametz (Ĥazon Ish  119:15; and see Hagalat Kelim 4:8-17). Since we know that Kaf Ha-ĥayim (451:100 and 107) states that the preferable custom is to be stringent and kosher the utensil according to its minority usage, and Rema and MB also state that one may only rely on the lenient opinion be-di’avad (see SHT ad loc. 144 and Hagalat Kelim 4 n. 18, against the implication of SAH 451:28 and 33, that this leniency is only be-di’avad), I have written that preferably one should be stringent and follow the minority usage, but in extenuating circumstances one may be lenient. This is true according to all customs. Regarding forks that are sometimes used in fire, there is an additional reason to be lenient and require only hagala – the fork that was used in the fire is batel in the majority of forks that were not.

10. Cleaning and Preparing Utensils for Hagala

A utensil must be cleaned properly before undergoing hagala, for although boiling water extracts the taste absorbed in the utensil, it does not clean the utensil of residual food stuck to its walls. If hagala is performed without first removing food residue, it is completely ineffective; the utensil must be cleaned, and hagala must be redone.

If the utensil has crevices containing food particles that cannot be removed, the residue can be incinerated via light libun. It is best to do so before performing hagala, but the utensil becomes kosher even if it the libun is done afterward (MB 451:25; see Kaf Ha-ĥayim 160).

If it is impractical to incinerate the food particles in these areas because it will damage the utensil, one may soak the utensil in a mixture of water and bleach or soap for a short while (thus rendering the food foul and inedible), and then perform hagala.[12]

Pot and pan handles must also be koshered because when metal vessels are heated during cooking, the heat spreads to the handles, and if they reach the temperature of yad soledet, the taste might be transferred to them. The handles of wooden pots must also be koshered, even though they do not become very hot, because hot food often spills over or splashes onto them, and they absorb the taste. Therefore, both the utensil and its handles must undergo hagala (SA 451:12; MB ad loc. 68). However, even if the pot itself absorbs at a heat of a kli rishon over fire, its handles can be koshered through irui from a kli rishon, because they do not absorb with the same intensity as a kli rishon over fire (Rema 451:12).

Many pots have handles that are attached with small screws, and food particles get stuck in their grooves. Therefore, before performing hagala the bolts must be taken off so that all of these particles can be removed. If this is difficult to do, one may soak this area of the pot in a mixture of water and bleach or some other harsh liquid cleanser in order to render the food particles completely befouled.[13]

[12]. Obviously, once the food residue in the crevices absorbs the taste of the soap, it is no longer edible and thus no longer forbidden (see also Hagalat Kelim 6:4). This seems problematic, though, as MA 451:5, Taz, and many other Aĥaronim state that knives comprised of two pieces cannot be koshered due to the food residue that is stuck in the groove between the pieces. They did not raise the option of simply befouling the taste of the food stuck in between. Perhaps a distinction can be drawn between the crevices that are near the food and grooves that are further away, like where the handle connects with the utensil (see SAH 451:21, which makes this distinction when be-di’avad one forgot to kosher the handle of a utensil). In truth, even the case of the knife needs further examination, since the reason for the rabbinic prohibition against using a utensil even twenty-four hours after absorbing prohibited matter is so that one will not mistakenly use a utensil within twenty-four hours of the absorption. However, the Sages did not include the food stuck in the grooves in this prohibition, and if this food is not fit for a dog’s consumption, it is no longer considered ĥametz. Perhaps one need not take the words of the Aĥaronim literally; rather, they just meant to teach that when the utensil has nicks and grooves that may have trapped ĥametz, simply performing hagala is insufficient. This matter requires further examination.

[13]. Regarding a pot in which one cooked prohibited food, if it is known that the pot did not boil over and its handles did not become hot, there is no need to kosher the handles. It is sufficient to boil water inside the pot, as will be explained below (section 13). Additionally, if the handles got hot but are attached to the pot with screws, they do not have to be koshered, since taste does not transfer from metal to metal. Similarly, if one accidentally put a dairy spoon into a meat pot, one must only kosher the section of the spoon that was submerged in the pot and the section that got hot, but not the rest. However, one must kosher the handles of a ĥametz pot, since there is a concern that perhaps during the year some ĥametz splattered onto the handles. Similarly, if one wants to kosher a ĥametz spoon, he must perform hagala on the entire thing; see MB 451:68.

11. The Reason to Wait Twenty-Four Hours before Hagala

It is customary not to perform hagala on a utensil until twenty-four hours have elapsed (and it is no longer “ben yomo”) since the last time it absorbed a forbidden food. This is because the absorbed taste remains flavorful during these twenty-four hours, and if the boiling water is not sixty times the volume of the utensil, the water will absorb the forbidden taste and transfer it back into the walls of the utensil, rendering the hagala ineffective. But if twenty-four hours have elapsed, the taste in the utensil becomes foul, and the utensil can be koshered even if the water is not sixty times its volume. This is because the utensil releases a foul taste into the water, and such a taste will not render the utensil un-kosher, even if it is reabsorbed. The utensil is only rendered un-kosher if it absorbed positive flavor, in which case it remains un-kosher even once the flavor has become foul. However, if at the time of its absorption the taste was foul to begin with, the utensil is kosher.

Another reason for this twenty-four hour delay is our concern that meat and dairy utensils will undergo hagala in the same water. In such a case, the positive flavors of meat and milk will be released into the water, and if the water is not sixty times the volume of either the meat or the dairy, they will not be batel. Rather, these flavors mingle and then render all of the water forbidden. Consequently, any utensil that undergoes hagala in this water will absorb basar be-ĥalav (the forbidden mixture of milk and meat) and become forbidden. However, once the utensil is not ben yomo, the tastes of milk and of meat in the utensils is foul, and even if the tastes mingle within the water, they do not become forbidden, since noten ta’am li-fgam is permitted (SA 452:2; MB ad loc.). Accordingly, one must ensure that a large pot in which other utensils undergo hagala did not absorb the ben yomo taste of meat, milk, or ĥametz.

The common practice at public hagala stations is to presume that at least some of the utensils brought are not ben yomo. In order to avoid problems, a strong cleanser such as bleach or liquid soap is added to the water, thereby immediately rendering any taste released by the utensils foul. Consequently, there is no concern that meat and dairy flavors will mix or that the tastes released will be reabsorbed by the utensils, because once a taste has become foul, it cannot render utensils forbidden.[14]

[14]. These principles are explained in SA 453:1-2 and in MB 1 ad loc. One who wishes to perform hagala must ensure that one of two conditions is met: 1) the utensil is not ben yomo, rendering any absorbed taste foul and thus incapable of rendering the utensil forbidden, even if reabsorbed; 2) the boiling water is sixty times the volume of the utensil’s walls, so that any taste released into the water is batel be-shishim. If many utensils are undergoing hagala, clearly the water will not have sixty times the volume of all the utensils collectively, so the custom is to kosher only utensils that are not ben yomo, lest the water have less than sixty times the volume of the utensils’ walls (Rema 452:2 and MB 20 ad loc.). These rules pertain to any forbidden food absorbed into a utensil, except for ĥametz. Regarding ĥametz, SA 452:1 states that if one boils a ĥametz utensil before the ĥametz actually becomes forbidden, hagala is effective even if the utensil is ben yomo, and even if the quantity of boiled water is less than sixty times that of the utensil walls, since the ĥametz was permitted at the time of its absorption. The only reason the utensil needs to be koshered is that it contains the taste of ĥametz in its walls, and taste that is released into boiling water and then reabsorbed into the utensil is not sufficient reason to require the utensil to undergo hagala again, as the reabsorbed taste is already twice removed from the original food (noten ta’am bar noten ta’am, or nat bar nat). One need only take care not to kosher ben yomo meat and dairy utensils together. Many questioned this ruling of SA, since in 451:4 it states that one must kosher utensils using libun if they absorbed ĥametz by fire, which means that SA follows those who maintain that ĥametz before Pesaĥ is considered “isura bala.” How, then, can it state in 452:4 that ĥametz before Pesaĥ is considered “heteira bala”? Indeed, Olat Shabbat, Pri Ĥadash, and Bi’ur Ha-Gra maintain that even when koshering a ĥametz utensil before the onset of the prohibition of ĥametz, one must ensure either that the utensil is not ben yomo or that there is enough water that anything absorbed in the walls of the utensil is batel be-shishim. This is the custom that is followed. (Perhaps, though, we can solve SA’s apparent contradiction as follows: Hagala addresses a situation of nat bar nat bar nat, in which the taste is thrice removed from its origins. Thus, SA felt it was appropriate to rely on the lenient opinion. But in the libun case, the taste is only once removed from its origins, so SA ruled stringently.)Regarding whether one may perform hagala on Pesaĥ: According to SA, it is permissible as long as the utensil is not ben yomo; merely having enough water is insufficient, since on Pesaĥ ĥametz is not batel be-shishim. According to Rema (447:10), even a drop of foul-tasting ĥametz renders forbidden whatever absorbs it on Pesaĥ. Thus, there is no permissible method of hagala on Pesaĥ. Only libun, which incinerates the taste absorbed in the utensil, is permitted on Pesaĥ.

Le-khatĥila, no other substance is mixed with the water used for hagala, as explained in Rema 452:5. Be-di’avad, hagala is effective in any liquid. MB ad loc. 26 states in the name of Pri Megadim that if Pesaĥ had not yet begun, one should re-kosher the utensil in boiling water alone. Nevertheless, in communal hagala it is difficult to ensure that everyone’s utensils are not ben yomo, and since we want to avoid any problems that could arise from mixing meat and dairy utensils, the custom is to add soap or bleach to the boiling water. See Sidur Pesaĥ Ke-hilkhato 7:20, which states that the validity of the hagala only comes into question if the water becomes thickened from the added substances. In n. 7 ad loc. it states in the name of Ĥazon Ish that it is preferable to use cleaning fluids to avoid the potential problem of mixing milk and meat and to avoid relying on the opinion that ĥametz before Pesaĥ is considered “isura bala.

12. Hagala in Practice

The hagala water must actually be boiling, and this is a sine qua non with regard to utensils that have absorbed ĥametz as a kli rishon on the fire. As we have learned, the practice, le-khatĥila, is to perform hagala on all utensils in a kli rishon over fire.

The entire utensil must be submerged in the water for a few seconds.[15] Sometimes the immersion of utensils cools the water to the point that it stops boiling. In this case, the utensils should be left in the water until it returns to a boil.

If a utensil cannot be immersed in its entirety into the water, it can be immersed one half at a time (SA 451:11).

Furthermore, when immersing two utensils into the boiling water at one time, one should shake the utensils to ensure that the boiling water circulates between them (based on SA 452:3-4).

Common practice, le-khatĥila, is to rinse the utensils with cold water after hagala, so that the hot water does not remain on them and cause them to reabsorb the taste released during hagala. This is not essential, however, since hagala is normally performed when the utensil is not ben yomo or in water that has a foul taste, so that even if the utensil reabsorbs the taste of the water, it will not be rendered un-kosher (SA 452:7; MB ad loc. 34). Therefore, one should not rinse utensils with cold water if this is liable to damage them. Likewise, if for some reason it is difficult to rinse a utensil with cold water, one need not make an effort to do so.

Though some people have reservations about performing hagala on their utensils, the procedure is actually quite simple. In brief: First, one cleans the utensil and waits twenty-four hours after it absorbed forbidden food. Next, one immerses the utensil in boiling water. If it is possible to take it out and rinse it immediately in cold water, this should be done, but if it is difficult, one may extinguish the fire under the pot of boiling water, wait for the pot to cool down somewhat, and then pour out the hot water, and rinse the utensil a bit in cold water. One may use any pot in the kitchen for hagala, provided that it has not been used for cooking in the previous twenty-four hours.[16]

[15]. See SA 452:1 and MB ad loc. 4, which state that one should not leave the utensils in the water for too long, so that they do not reabsorb what they released. On the other hand, too short a time in the water will not give the utensils enough time to release. MB states that it is difficult to ascertain the precise amount of time that is neither too quick nor too long. However, it states: “If one performs hagala before the time that [ĥametz] becomes forbidden, there is no need to be so precise, and one may leave [the utensils] in the water longer,” since at that point noten ta’am li-fgam is permitted and the ĥametz is batel be-shishim. See Kaf Ha-ĥayim 452:2 which states that some Rishonim maintain that one should leave the utensils in the water until they have released what they absorbed, while other Rishonim maintain that one should insert the utensils in the water and then remove them immediately. Common practice follows the latter opinion, and Pri Ĥadash states, regarding this practice, that Jewish custom has attained the status of law (see Sidur Pesaĥ Ke-hilkhato 7:17 and n. 67). The prevalent custom is to leave the utensils in the boiling water for about three seconds.

[16]. The custom of Ashkenazic communities and some Sephardic communities is to avoid using hagala to switch utensils from meat to dairy and vice versa, so that one does not forget which utensils are meat and which are dairy. However, if a utensil became non-kosher and one koshered it through hagala, he may use it for whatever he wants (if it was meat before, he may use it for dairy and vice versa). Similarly, Ĥatam Sofer §101 states that following the hagala for Pesaĥ, one may change the status of his utensils. One who receives a utensil as a gift may change its status through hagala (Darkhei Teshuva YD 121:59). One may also sell the utensil to a friend, reacquire it, and then change its status through hagala. (Pri Megadim [Eshel Avraham] 452:13, states that in extenuating circumstances one may change the status of his utensils through hagala.)

13. Koshering Pots via Hagala

We have seen that in order to kosher a pot used to cook ĥametz (barley soup, for instance), it must be immersed in boiling water. When the boiling water inundates the vessel on all sides, it extracts the taste of the ĥametz from it. Based on the principle of ke-bole’o kakh polto, it ought to be possible to kosher such a pot by simply boiling water in it, and the pot will expel the taste just as it absorbed it. However, during the course of the year some cooked foods certainly boiled over the sides of the pot, causing the absorption of taste along the pot’s rim. The taste would not be released by water boiled inside the pot. Thus, in order to kosher such a pot for Pesaĥ, it must be completely immersed in a large vat of boiling water.

If one cannot find a vat large enough for immersing the pot one wishes to kosher, the poskim suggest the following: fill the pot you wish to kosher with water and bring it to a boil. At the same time, heat a stone so that it becomes scorching hot. When the water boils, insert the scorching hot stone into the pot. This will cause a lot of water to spill over the sides of the pot, koshering its rim and its outer walls.

This method is effective where a vessel has absorbed ĥametz through overflow, but if a pot was inserted into another pot and absorbed taste, it has absorbed in a kli rishon, and hagala by the overflow method is not effective. Instead, it must be koshered through complete immersion in boiling water (SA 452:6; MB ad loc. 31).

It is difficult, however, to heat stones in this manner in domestic kitchens. Therefore, a possible alternative is to boil water in a small vessel, and when the water in the large vessel begins to boil, insert the small vessel into the center of the larger vessel. This will cause the water in the larger vessel to overflow and kosher its rim and outer walls.

If the pots have removable handles, it is proper to remove them and perform hagala on them. However, if the handles were not removed, and one cleaned around them with plenty of soap and then performed hagala on them, the pot is kosher.

Another problem is that many pots have a lip along the rim and on the edges of the cover where food sometimes gets stuck. The preferred practice is to heat these areas with a blowtorch in order to incinerate the residue found there. However, one need not be meticulous about this, because the pot goes through enough rinsing and cleaning with detergents to render the taste of any residual food foul and unfit for a dog’s consumption, so that it does not even have the status of ĥametz. Therefore, if a blowtorch is used, its flame should not be directed at one place for too long, because doing so might damage the pot’s nice appearance. When necessary, one who cannot perform light libun on this lip may suffice with hagala.[17]

[17]. We once examined the lip of a pot, and the substance contained in it was black, ugly, and extremely foul-tasting. Therefore, even without libun it is not forbidden. Similarly, whatever builds up around the pot handles is exceedingly foul, so even if one did not remove the handles, the hagala is valid. Nevertheless, to be on the safe side, one should rinse that area with a lot of soap. Regarding hagala on a large pot that does not fit inside an even larger pot, I have seen it suggested that one cause the water to overflow by pouring boiling water into it from an electric kettle that is still connected to a power source. My solution is better, though, since with the pouring method, the water cools down slightly, whereas in my method, the whole pot boils and becomes a kli rishon without cooling down at all.

Regarding milk and meat: Sometimes some liquid from a boiling dairy pot splashes onto a cold meat pot, and we consider the outer layer of the meat pot to have absorbed some dairy taste at the spot that was hit by the liquid. The way to kosher the meat pot is by pouring boiling water on it, and since we are dealing with a very small absorption, one need not even wait twenty-four hours, since it is possible to pour sixty times the amount absorbed on the spot. If one is concerned that there is not sixty times the absorbed amount, he may mix soap into the boiling water, which will befoul the absorbed taste. On the other hand, if the meat pot contained hot food when it was splashed by the dairy liquid, the pot needs to be koshered in boiling water. One should consult with a halakhic authority about the status of the food in the meat pot, since sometimes it is sufficient to have sixty times the amount of dairy liquid, while other times there needs to be 3,600 (sixty times sixty) times the amount of splashed liquid.

14. Absorption through Pickling (“Kvisha”) and Its Koshering

Utensils into which cold ĥametz has been placed do not require hagala in boiling water; a thorough washing is sufficient to kosher them for Pesaĥ. For example, beer mugs become kosher for Pesaĥ by means of a thorough washing, even though beer is ĥametz gamur, because as long as the ĥametz in a utensil has not reached the temperature of yad soledet, the utensil does not absorb the taste of its contents. Certainly, then, a cake plate used for ĥametz can be koshered for Pesaĥ with a thorough washing, because in addition to the fact that cookies never reach yad soledet, they are dry, and taste does not transfer to a utensil without a liquid medium.

But if beer is left in a mug for more than twenty-four hours, kvisha (“pickling,” or the absorption of taste through prolonged soaking) occurs, and the taste of the ĥametz gets absorbed into the glass based on the Sages’ rule: “kavush ke-mevushal” (pickling is akin to cooking). Therefore, it is forbidden to use such a utensil on Pesaĥ unless it has been koshered.

Utensils that have absorbed taste via kvisha can certainly be koshered through hagala in boiling water; if hagala is effective on utensils that absorbed via cooking, it certainly works on utensils that absorbed via kvisha. Moreover, since kvisha is a milder form of absorption, one may kosher such a utensil by soaking it in water for three twenty-four hour periods: First, one places the utensil in water and leaves it there for twenty-four hours. Second, the water is changed and the utensil is left there for another twenty-four hours. Then the water is changed once again, and the utensil soaks for a final twenty-four-hour period. Nevertheless, this method of koshering is generally not helpful because it is faster and easier to perform hagala with boiling water. But when dealing with utensils that are liable to be damaged by boiling water, soaking in water for three twenty-four-hour periods can be a very useful solution.

It is also worth mentioning that when it comes to alcoholic beverages such as whiskey, some poskim are of the opinion that the taste of the ĥametz is absorbed by the glass in a mere eighteen minutes. Thus, if one wishes to use such a glass on Pesaĥ, it must first be koshered using one of the aforementioned methods.[18]

[18]. See Kaf Ha-ĥayim YD 105:1 on the dispute among the poskim regarding the degree to which, vis-à-vis prohibitions other than ĥametz, utensils absorb taste via the pickling process. Some poskim maintain that utensils absorb taste via pickling to the same degree that they do via cooking, while others maintain that pickling causes utensils to absorb taste only in their outermost layers. Kaf Ha-ĥayim concludes that one may rely on the lenient opinions to prevent a significant financial loss. For example, if one cooked in a pot that had previously contained prohibited liquids for a period of twenty-four hours, one may rely on the lenient opinions that permit the food, since the amount absorbed in the outermost layer of the pot is not sufficient to prohibit the food. On the other hand, when not dealing with a significant loss, one should be stringent, following the many authorities that consider the food forbidden. It is clear that one preferably should not use utensils that have had prohibited liquid in them for more than twenty-four hours. Regarding the pickling time for a sharp food, Darkhei Teshuva 105:42 states that there is a dispute: some say it takes ten minutes (Yad Yehuda) and others say eighteen minutes (Tiferet Yisrael). It is also uncertain whether these times apply to absorption into a utensil as well. Nishmat Adam 57:10 and Binat Adam §59 state that, according to Shakh, even the taste of a sharp food is only absorbed into a utensil after twenty-four hours, while according to MA the taste of sharp foods is absorbed more quickly. Preferably, one should be stringent. See Sidur Pesaĥ Ke-hilkhato 6:5.

Even though an earthenware utensil that absorbed ĥametz during the cooking process cannot be koshered through hagala, if such a utensil absorbed the taste through the pickling process, it can be koshered through hagala or through soaking for three days, as per SA 451:21. See also MB ad loc. 118 and Kaf Ha-ĥayim 242, which state in the name of Shakh YD 135:33 that the leniency of permitting one to kosher an earthenware vessel that absorbed forbidden taste via pickling applies only to ĥametz and not to other forbidden foods.