ISSUE 23 אדר תשע"ב / MARCH 2012
start with a more detailed OULIES J description of the product. Two inventors came up with an PCM interesting product that they The company is understandably called “Joulies” (pronounced secretive about what the “Joo-lees”). Each Joulie Joulies are filled with, but looks like a 2 inch-long we were able to come stainless steel coffee up with an educated bean and is filled with a guess as to what the proprietary material. The material is. We based this material inside the Joulie on (a) the pieces of is designed to absorb information they heat that is more than Joulie – cut open provided, (b) review of 140° F and then release scientific literature on the that heat when the topic, and (c) physical surrounding area cools and chemical analysis of below 140° F. Consumers the material, as follows. are supposed to put Joulies into their coffee The company website mugs so that the Joulies Joulie – after some PCM melted and literature note that will quickly cool the Joulies are, “filled with a coffee to a drinkable proprietary substance temperature; then as the called a ‘Phase Change coffee cools the “magic Material’ (PCM) that beans” release their heat melts at 140°F and is 100% and thereby maintain the edible food-grade temperature of the magic.” The company also told coffee. This article will address a me (via email) that “the PCM number of questions (kashrus, inside is made from plants”. Shabbos, and others) that are raised by this product. We will We purchased a set of Joulies and had one cut open revealing
Sappirim is a cRc publication written by Rabbi Dovid Cohen and edited by Ms. Biranit Kohn Page 2 Sappirim that the PCM is a white, waxy, the PCM’s melting point, the somewhat-grainy material. When latent heat in the liquid PCM is the (open) Joulie was put into released back into the boiling hot water, the PCM began surrounding material as the PCM to melt and the liquid floated to changes back into a solid. the top of the water. [After the water cooled, the liquid solidified.] In recent years, a number of papers have been written in The following is a helpful definition scientific journals2 detailing the of the term “Phase Change dozens of different PCMs Material”: available and describing the PCM materials have high heats properties of each. Armed with of fusion so they can absorb a the knowledge that the PCM used lot of energy before melting or in Joulies has a melt-point of 140° solidifying. A PCM temperature F, is a food-grade material, is remains constant during the claimed to be made of plant phase change, which is useful materials, and has a solid waxy for keeping the subject at a consistency at room temperature, uniform temperature.1 we reviewed some of those articles to see if we could pinpoint In other words, a PCM is a type of which PCM is inside a Joulie. This material which requires a investigation showed that the relatively large amount of energy PCM used in Joulies is most likely to convert it from a solid state/phase to a liquid state/phase (i.e. high heat of 2 For purposes of this investigation, the most fusion) such that the material helpful article was, Review on Thermal Energy Storage with Phase Change: Materials, Heat absorbs heat/energy as it melts Transfer Analysis and Applications, by Belén (i.e. as it changes “phases”). Thus Zalba, José Marín, Luisa F. Cabeza, and Harald Mehling in Applied Thermal Engineering 23 the material remains at a (2003) 251–283 available at constant temperature (its melting http://ecaaser5.ecaa.ntu.edu.tw/weifang/pcm point) as it changes from a solid /Review%20of%20PCM.pdf. Other articles can be found at into a liquid. When the http://resource.tcc.edu.tw/resdata/3703/a%20r surrounding material cools below eview%20on%20phase%20change%20energy%2 0storage--materials%20and%20applications.pdf, http://www.iea- 1 shc.org/publications/downloads/task32- http://www.colorado.edu/engineering/ASEN/as Inventory_of_PCM.pdf, and en5519/1999-Files/presentations/ben- http://web.mit.edu/3.082/www/team2_s02/pha mottinger.pdf. se_change.html.
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palmitic acid which has a melting claims,5 the palmitic acid is point of 61-64° C (142-147° F) or commonly produced at high possibly myristic acid (which has a temperatures on large equipment melting point of 49-58° C / 120- which is also used for animal fat. 136° F). Both of these fatty acids Thus, even if the Joulie PCM is, in have a relatively high heat of fact, “made from plants” it might fusion (185-204 kJ/kg), are waxy not be kosher.6 solids at room temperature, and can be food-grade materials There are, however, a few reasons made of plant products. We then why even if the PCM is not kosher, had a cRc certified company run one might still be permitted to use the PCM through a Gas it in hot kosher beverages. Chromatography (GC) Mass Spectrum which confirmed that it Firstly, a Jew who tasted the PCM is, in fact, palmitic acid.3 said that it was basically tasteless Kashrus with a waxy consistency. If so, it would seem that we should be Palmitic acid is definitely a kosher- able to apply the ruling of Rema sensitive ingredient, as it is often 103:2 that one does not have to derived from animal fat,4 and be concerned about b’lios from even when it is derived from plant forbidden items which are materials, as the company
3 The test also showed traces of oleic acid. Oleic acid is not a known PCM and therefore it is most likely that the traces of oleic acid are 5 There may be basis for accepting the due to impurities in the palmitic acid rather than company’s claim even as relates to a potential אומן לא an intentional additive. issur d’oraisah based on the principle of see Shach 98:2 and Iggeros Moshe) מרע אמנתו Palmitic acid (like most fatty acids) is isolated 4 by “splitting” fats or oils at very high YD 1:55). temperatures (~700° F) into two parts – glycerin 6 If the PCM is plant-based and is only non- and fatty acids. The mixture of fatty acids kosher due to absorbed non-kosher taste, אין הבלוע derived from the given fat or oil is then further should we possibly apply the rule of Shulchan Aruch 105:7) and say) יוצא...בלא רוטב processed at high temperatures (~150-250° F) to separate, purify, and deodorize them for use. that the absorbed ta’am cannot transfer into The sophisticated equipment used for these the stainless steel shell since there is no liquid processes is (a) at times used for both animal medium between the PCM and shell? This and vegetable products, (b) often not cleaned suggestion is incorrect for two reasons: 1) The between products (since the products do not absorbed non-kosher animal fat is a davar easily spoil, and the distillation and other shamein which most hold can transfer from purifications remove impurities), and (c) food into a kli without a liquid medium (see relatively large (such that absorbed non-kosher Badei HaShulchan 105:112), and 2) when the taste may not be batel b’shishim into Joulie is put into hot water the PCM changes subsequent kosher products). into a liquid!
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tasteless.7 There are a number of who assumed that bee legs are concerns with this line of tasteless even though we can reasoning: only imagine that he never It would seem that a decision actually tasted them. that the PCM is tasteless should Scientific reference works8 be based on the tastings of indicate that palmitic acid has multiple people. almost no “taste” but does Whether other Jews are provide some element of permitted to taste the safek issur mouthfeel. Seemingly, mouthfeel and whether the permitted level qualifies as “ta’am” even if of tasting is sufficient to determine scientifically it may not be that the food is tasteless is considered “taste”, which would discussed in Taz 98:2, Pri Megadim imply that these items are not ad loc, and Yad Yehuda 98:2. “tasteless”. On the other hand, it On the other hand, it may be may well be that the subtleties sufficient that the gut reaction of detected by flavor chemists may all those who saw and touched be too insignificant to qualify as the PCM was that it would be “ta’am” for the average person. tasteless, and this may not be Toras Chattas (Rema), Shach and much different than Rema ibid. others say that nowadays one may not rely on a Jew’s tasting of 7 This line of reasoning was suggested by R’ Elli a food to determine that it does Leibenstein. See Aruch HaShulchan 103:19 and not have a taste of meat so as to Pri Megadim SD 103:2 who explain why the case of tasteless food is different than the case of then l’chatchilah mix it with dairy; Shach 103:2 of food which is nosein ta’am but rather, “tasting” (even by a Jew) the ta’am does not contribute positive (or is only relied upon for cases of negative) taste into the kosher food. If this line of reasoning is legitimate, it would b’dieved.9 The reasons10 given seem that one could even l’chatchilah put the Joulie into hot coffee and it would not be considered bitul issur l’chatchilah, because (a) 8 Fenaroli page 1478 and Arctander 2447. in this case where no one will eat even a drop 9 Shulchan Aruch 98:1 codifies the Gemara’s of the forbidden PCM, and there is no ta’am halacha that there are situations in which one transferring into the coffee, it is not clear that can rely on a non-Jew’s tasting of a food to this even qualifies as bitul issur at all since the determine that it does not have an absorbed person is not putting issur into the heter, (b) non-kosher taste. Rema records that the there are those that hold that the issur Ashkenazic custom is to not rely on a non-Jew’s d’rabannan of bitul issur l’chatchilah does not tasting under any circumstance. Shach 98:5 apply to safek issur (see Badei HaShulchan deduces from Rema’s wording that this custom is limited to a non-Jew’s tasting, but if a Jew אין and (c) this case may well qualify as ,(99:29 where bitul issur l’chatchilah does not tastes a food and says that it does not have the כוונתו לבטל apply. taste of issur (e.g. terumah, meat), then one
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for this chumrah would appear to through the metal shell, and the also apply to determining that a ability for ta’am to pass through food is tasteless. Does this mean metal is itself a safek.11 that one may not l’chatchilah use Joulies in hot beverages even In addition, Joulies are never used if multiple Jews and scientific in a kli rishon, and the PCM only publications would inform us that has contact with hot beverages the PCM is tasteless? as a kli sheini.12 If so, ta’am On the other hand, it may be cannot transfer more than k’dei 13 that our case is somewhat more klipah, which means that ta’am lenient due to the fact that (a) from the PCM cannot transfer the PCM is only safek issur, (b) no through the k’dei-klipah-thick one will ever eat the PCM but stainless steel shell. Therefore rather our concern is that it is even if the PCM is non-kosher, the nosein ta’am into the beverage, status of the hot coffee or other and (c) the only way it can be beverage should not be affected nosein ta’am is if taste passes by the PCM. [Furthermore, b’dieved one does not have to be concerned about the transfer may rely on that determination and permit the food. Shulchan Aruch 96:1 continues with this 11 See Shulchan Aruch 92:5 and the Poskim ad assumption and says that if a radish was cut loc. We calculated that each Joulie holds with a meat knife, one may eat the radish with approximately 0.5 cubic inches of PCM and the dairy if a Jew tastes the radish and determines company recommends that one Joulie be used that it does not have a meat-taste. However, for every 4 ounces of beverage. At that ratio, Toras Chattas (Rema) 61:1 and Shach 96:5 there is approximately 16 times as much argue that although we have seen above that beverage as PCM. [4 ounces is approximately a Jew’s tasting may be relied upon, that is 7.2 cubic inches, and the metal in the Joulie is limited to cases of b’dieved where the food approximately 0.8 cubic inches] That is not was already mixed with issur (or the meat enough for bitul b’shishim but does somewhat suspected of having absorbed a meat taste has minimize the concern, especially if the PCM is already been mixed with dairy), but one may basically flavorless (see Shach 103:5). not rely on even a Jew’s tasting to make a 12 The company advises that one put the Joulies l’chatchilah decision to mix two foods together. into the mug before pouring the coffee in such The l’chatchilah use of a Joulie in a kosher a way that the outer shell’s contact with the hot beverage based on a Jew’s tasting of the PCM beverage is via irui kli rishon. However, as and determining that it is tasteless, would relates to the PCM (which is the potential non- appear to be an example of the case where kosher item) the contact is irui kli rishon which is which has the status of a kli sheini ,נפסק הקילוח Toras Chattas and Shach say that one may not rely on even a Jew’s tasting. (Rema 68:10). [If, as we suspect, some people 10 Pri Megadim SD 96:5 cites two reasons for this: put the Joulies into the mug after the coffee is 1) there may be a mashehu of taste, and 2) already inside, even the contact with the shell nowadays, we may not be sufficiently capable will be as a kli sheini.] of detecting taste. 13 See Rema YD 92:7 and elsewhere.
Page 6 Sappirim of ta’am in a kli sheini.]14 The The PCM appears to be concerns with this line of tasteless, such that (a) it’s b’lios reasoning are: cannot affect other foods, and If a person would ever put his (b) any minimal taste may Joulies into the dishwasher – and possibly be batel b’shishim (see if a dishwasher has the status of footnote 11). a kli rishon15 – the (possible) non- The PCM only has indirect kosher taste of the PCM would contact with the beverage and be fully absorbed into the it is a safek if (and how much) stainless steel shell such that it ta’am can pass through metal. could subsequently be released The Joulies are only used in a kli 16 even with an irui kli rishon. sheini, such that (a) b’lios On the other hand, it is generally cannot pass through the shell, assumed that any b’liah that is and (b) b’dieved we are not extracted via an irui kli rishon (i.e. machmir for kli sheini. when coffee is poured over the Joulie) is batel b’shishim into the Although there are questions on hot water. some of these individual reasons Summary and some only apply b’dieved, it Joulies are filled with a material seems that the combination of all known as PCM that may possibly of these factors may be enough be non-kosher. The reasons to to permit the use of Joulies in nonetheless consider permitting kosher foods. Others will the use of Joulies in hot kosher undoubtedly choose to be beverages are that: machmir and not use them due to the kashrus concerns. The PCM is only safek issur. Under the assumption that the use of Joulies does not pose a general kashrus concern, we now turn to 14 Rema 68:11. some other questions that relate 15 For a thorough treatment of the status of dishwashers see the sources and discussion in to their use. the article on dishwashers by Rabbi Yisroel Rosen in Techumin 11. 16 In addition, should we be concerned that in the factory the Joulies are likely sealed shut with direct heat (welding), and therefore each was used as a kli rishon (albeit not in the presence of a kosher beverage)?
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Other Kashrus Issues Magen Avraham21 clarifies that as Some of the leniencies noted relates to this halacha ambient above do not apply on Pesach,17 temperature animal fat has the and it therefore seems prudent to status of a solid food even though be machmir and not use Joulies it liquefies as it warms up. He (even new ones) on Pesach. therefore rules that the prohibition against cooking on Shabbos does It is obvious that one may not use not apply to animal fat which was the same Joulie for both meat cooked before Shabbos. We can (e.g. soup) and dairy (e.g. coffee apply this same principle to the with milk). Furthermore, the palmitic acid PCM;22 it was custom is that if one owns two of cooked before Shabbos23 and is the same item and one is now in solid form such that if one designated for dairy use and the would put a Joulie into hot water other for meat use, the one there would be no violation of the designated for dairy use should prohibition against cooking on be “marked”18 so that it will not Shabbos.24 mistakenly be used for the wrong use. However, it would seem that it is forbidden to put use Joulies with Shabbos The general rule is that the 21 Magen Avraham 318:40 cited in Mishnah prohibition against cooking on Berurah 318:100. Shabbos does not apply to foods 22 Iggeros Moshe OC 4:74:f (in the bishul section) and Shemiras Shabbos K’hilchaso 1:58 (as which have already been cooked explained there in footnote 173) disagree as to whether Magen Avraham’s leniency applies to 19.(אין בישול אחר בישול) once before Foods which are in liquid form are butter which is cooked in a liquid form (as milk) and cools (i.e. attains an “un-cooked” status) an exception to that principle, before it solidifies, in the same way that it because once the food cools applies to animal fat which solidifies (i.e. 20 becomes a solid) as it cools. However, the down it loses its “cooked” status. physical properties of palmitic acid are similar to that of animal fat (both solidify as they cool) and therefore all would agree that Magen Avraham’s ruling applies to PCM. 17 For example, b’lios in a kli sheini are forbidden 23 As noted in an earlier footnote, one step in even b’dieved (Rema 447:3 as per Mishnah separating fatty acids such as palmitic acid Berurah 447:25). from oils (or fats) is to cook the oil at very high 18 Rema 89:4 (end). temperatures (~700° F) which obviously qualifies 19 Shulchan Aruch 318:15 as per Mishnah as a “cooking” for that oil. Berurah 318:92-93 & 95. 24 In addition to the reason noted in the text 20 Shulchan Aruch/Rema 318:15 as per Mishnah there is no prohibition of bishul in this case Berurah 318:24 & 99. because the Joulie is placed into a kli sheini.
Page 8 Sappirim hot beverages on Shabbos due to their use in kosher beverages. the issur d’rabannan of nolad, Separate Joulies should be used intentionally converting an item for meat and dairy. One may not from solid to liquid form.25 We use Joulies on Shabbos, and it have already seen that this seems appropriate not to use change in form is critical to the them on Pesach. Before Joulies Joulie performing its “magic”, and are used, they should undergo therefore that change is tevillah with a bracha. considered intentional and forbidden. MULTIPLE MATZOS BAKED AS A Tevillas Keilim SINGLE SHEET The functional portion of the Joulie is the PCM which is a In some machine matzah material that does not require bakeries, the matzos go through tevillas keilim. However, since the the entire oven as one long sheet. stainless steel shell comes in As an introduction to the two contact with the food, and the halachic issues Connected matzos leaving oven Joulie would clearly not function raised by that Picture courtesy of http://bit.ly/3dRYz without the shell, the Joulies must practice, we will review undergo tevillas keilim before they Connected are used, and one should recite a some details of Matzos bracha on that tevillah.26 how these types of Summary machine Single Joulies are filled with a material matzos are Matzah known as PCM that may possibly formed and baked. After the be non-kosher, but there are dough is kneaded, it is rolled into nonetheless reasons to permit a long, flat sheet which passes under two sets of blades that score the sheet lengthwise and 25 Rema 318:16 as per Mishnah Berurah 318:105. In our case, it appears that all conditions of widthwise. These blades score the nolad (a meaningful amount of liquid which sheet into matzah-sized squares does not immediately become mixed into another food) apply. but do not cut the dough all the 26 Based on Rema 120:7 (end). Chochmas way through; rather, the matzah Adam 73:11 says that this type of case requires passes through the oven as a tevillah and the fact that he does not say “tevillah without a bracha” (as he does for scored sheet, and after it leaves other cases in that same halacha) implies that a bracha should be recited in this case.
March 2012 Page 9 the oven it is broken into individual 2. Shulchan Aruch30 says that if matzos. a loaf of bread is broken in half, a Shalem person can join the two pieces together with a toothpick and The most well known issue that this consider the newly-connected setup raises is that perhaps the loaf to be a shalem.31 individual matzos should not be considered shalem in terms of Some question these proofs using them for lechem mishneh. (and particularly the first one) [This issue is relevant year-round based on Machatzis HaShekel32 and is not specific to Pesach.] who suggests that these How can a single matzah be halachos may only apply in considered “whole” if it was cases of b’dieved. However, baked as part of a 300-matzah- others33 rejoin that (a) Minchas long sheet? Although this Pitim34 clearly disagrees with question seems compelling, most Machatzis HaShekel’s Poskim27 hold that the individual suggestion, and (b) there is matzos are, in fact, considered reason to think that in our case it shalem and they offer three is even more obvious that the reasons for this position: individual matzos are considered shalem because the 1. Shulchan Aruch28 rules that if joined matzos were specifically two pieces of dough were stuck scored to begin the separation together in the oven and were then separated from one another after baking, the individual Hungarian Rabbonim before WWII; the journal is have the status of being available at http://hebrewbooks.org/538, and גלוסקאות the first four entries are on the topic of machine matzos which are baked in one attached גלוסקאות shalem (and the joined do not).29 sheet.] 30 Shulchan Aruch 168:2. 31 Tzur Yaakov 151 (Rav Avraham Yaakov 27 Many of the sources brought to the author’s Horowitz), available at attention are from the discussion on this topic in http://hebrewbooks.org/1116. She’arim Metzuyanim B’halacha 110:23, 32 Machatzis HaShekel 274:1 (end). available at http://hebrewbooks.org/14619. 33 Orchos Chaim 274:2 (a) and Rav Sofer in 28 Shulchan Aruch 168:3. A similar proof is Yerushas Plaitah #1 (b). brought by Minchas Pitim (see below) from the 34 Minchas Pitim (Rav Meir Arik) 274 & 648, .cited in available at http://hebrewbooks.org/37527 (אתרוג התיום) halacha of a double-esrog Shulchan Aruch 648:20. This also appears to be the opinion of Shoel 29 Rav Mordechai Ephraim Fischel Sofer writing in U’Maishiv I:I:167 (towards the end), referenced Yerushas Plaitah #1. [Yerushas Plaitah is a in Da’as Torah 274:1, regarding the use of journal printed in Budapest in 1946 which challos (stuck together during baking) for features divrei Torah written (primarily) by lechem mishneh.
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process (as opposed to the case already baked.37 [The discussion of Shulchan Aruch/Machatzis regarding point “a” is beyond HaShekel where the separated the scope of this document.] matzos were unintentionally Rav Sofer38 replies to point “b” joined). that (c) the scoring of the 3. There is a principle that at matzah before it enters the oven times a larger item can be sufficiently indicates the considered divided into individual intention to eventually divide the parts if the original intention is to sheet, and (d) the oven can later break it up. Rav Sofer and function well if there is even a 39 Tzur Yaakov35 suggest that this minimal connection between .the portions of the sheet כל העומד לחתוך principle, known as can be applied to our ,כחתוך דמי case where the matzah is only Rav Sofer and Rav Mordechai 40 temporarily maintained as a long Meir Bennet support their overall sheet and the obvious intention is lenient positions by citing the to break it into individual matzos “minhag in all of Poland” to after the baking. purposely bake 12 pieces of dough together (for non-Pesach 36 Rav Shteif argues that (a) the use) and then use the individual above principle is the subject of pieces as whole challos/rolls for a halachic dispute, and the lechem mishneh. accepted halacha (at least in this type of case) does not Heating of the dough follow this opinion, and (b) The fact that the dough enters the although it is clear that the sheet oven and is baked as one long will be broken into individual sheet raises another question matzos after it leaves the oven, it is equally clear that in order for 37 Tzur Yaakov ibid. makes a similar point (regarding to a leniency he suggests based on the oven to function properly the experiment noted in Shulchan Aruch 167:1) the sheet must remain whole but concludes with a proof that the matzah is until it leaves the oven such that considered shalem for other reasons, as noted earlier in the text. .until it is 38 Yerushas Plaitah #3 עומד לחתוך it is not 39 In fact, in most ovens the dough must merely be attached when it enters the oven (so that the dough that is not yet in the oven will be 35 Rav Sofer in Yerushas Plaitah #1, and Tzur pulled onto the oven-belt), but once it is on the Yaakov ibid. oven-belt there is no need for the individual 36 Rav Yonnason Shteif writing in Yerushas matzos to be attached to one another. Plaitah #2. 40 Yerushas Plaitah #1 & #4.
March 2012 Page 11 which is particular to Pesach. It is utensils.44 Chazon Nachum45 cites well known that matzah-dough others who agree with that חם cannot be at all warm (before it is position but then argues that .does apply to foods מקצתו חם כולו baked), because that might cause it to become chametz in He therefore supports a Rav in less than 18 minutes. Accordingly Antwerp who forbade the use of Rav Shteif41 wonders if the dough Pesach matzah baked as one which is not yet in the oven might long sheet.46 Those illustrious get hot/warm, because it Rabbonim who have permitted attached to the dough which is the use of multiple matzos baked already baking in the oven. In as a single sheet have apparently response to this, Rav Sofer and adopted the lenient position on Rav Bennet42 report that their this question. experience showed that the dough shows no sign of heat before it goes into the oven, and BUTYL COMPOUNDS they were therefore unconcerned Butyric acid is a carboxylic acid with this issue. Rav Bennet further with 4 carbons (and is technically suggests that even if the dough known as butanoic acid), which is would be very hot for a few most commonly found as a seconds before it gets into the component of (rancid) butter. oven that would not be enough The following are notes from the time for it to become chametz.43 June 2008 AKO Ingredient Meeting: The aforementioned Poskim Rabbi Gornish reported that the specifically note that their OK does not consider butyric discussion presupposed that the acid a Group 1, because of a does חם מקצתו חם כולו principle of concern that it is produced not apply to foods and is limited from grape-based fusel oil. The to heat spreading through metal committee members agreed
41 Yerushas Plaitah #2. 44 In other words, they were focusing on whether 42 Yerushas Plaitah #3 & #4. the dough outside the oven is perceptibly hot 43 He notes that although Shulchan Aruch 459:2 and not whether the halacha dictates that we implies that in such circumstances the chimutz should consider it hot. can happen instantly, those words should not 45 Chazon Nachum YD 45, available at be taken literally; it actually takes some time for http://hebrewbooks.org/819. the dough to become chametz. [See Mishnah 46 This also appears to be the conclusion of Berurah 459:18 who makes a similar point.] She’arim Metzuyanim B’halacha 110:23.
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that butyric acid can be compounds are not Group 1 as isolated from fusel oil, but they may come from butter or argued that the amount of work fusel oil.48 required to isolate and purify butyric acid from fusel oil made it not commercially viable to do HOT BOX KASHERING so. Therefore all butyric acid Background should be assumed to be from A hot box is an insulated box into synthetic sources.47 Thus, the which one puts pans or plates of consensus was that although food to either maintain or fusel oil and even isoamyl increase alcohol are not considered their Group 1 because they may be temperatur derived from grape-based e. Some of alcohol, butyric acid and butyl them have compounds should be Group 1. built-in Rabbi Gornish accepted these heating Hot Box (midsized) arguments, and on the day elements, and others are heated after the meeting he reported by putting “Sternos”49 onto the that Rabbi Don Yoel Levy was floor of the hot box. The boxes amenable to the OK changing range in size from approximately its policy on this issue; the butyl 10,000-90,000 cubic inches50 and compounds could therefore be included on the Group 1 list. 48 Some literature indicates that it can also be made via fermentation. Based on the above, butyl (a.k.a. 49 Sterno is a brand name for portable, butanoic) compounds are Group disposable canisters of chafing fuel (a flammable gel or liquid). The Sterno brand is so 1 as they are assumed to be popular that all varieties of these canisters are synthetic, but the “natural” version colloquially known as “Sternos”. 50 A hot box’s cubic inches are calculated by of butyric acid or butyric multiplying its (interior) height by its width by its depth. Thus a hot box which has an interior height of 59 inches, width of 60 inches, and 47 Additionally, it was noted that (a) Rema depth of 25 inches will have 88,500 cubic inches 114:10 (as explained by Shach 114:21) holds (59 X 60 X 25 = 88,500) of interior space. Most that in cases such as this, one need not be hot boxes are wider than they are tall, and can concerned that the item is produced from stam be divided into the following four approximate yayin and (b) grape-based fusel oil is often used sizes extra large (>80,000 cubic inches), large specifically for natural grape flavors, because (70-80,000 cubic inches), medium (60-70,000 that fusel oil is believed to carry trace notes that cubic inches), and small (<60,000 cubic inches). are appropriate for a grape flavor. Upright hot boxes come in “full” (20,000-40,000
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are ubiquitous in banquet hall non-kosher. The fact that a kitchens where a caterer might heating element or Sterno is often use many hot boxes for a given heating the chamber (in addition event. to the hot food) means that the hot box is absorbing ta’am as a kli In addition to the traditional uses rishon rather than via irui kli rishon, for a hot box, kosher caterers will and the level of kashering must be sometimes use them as “portable commensurate with that status. ovens” when they are catering an event at a non-kosher venue. The Of course, it is not possible to caterer will cook all food in his perform a traditional hag’alah to kosher commissary, and instead of a hot box, and therefore the cleaning and kashering the standard method of kashering hot hotel’s ovens he will use hot boxes boxes has been with libun kal52 to heat up the food at the event.
(see Shulchan Aruch 92:8). If/when steam from Since hot boxes are regularly used kosher food condenses on the ceiling of the hot for the storage of hot food, there box and drips into the food, the non-kosher b’liah will transfer into the (previously) kosher is no question that a non-kosher food (see Rema 108:1 and the limitation noted hot box cannot be used unless it is in Iggeros Moshe YD 1:40). The floor of the hot kashered beforehand. The zei’ah box could possibly absorb non-kosher taste through dripping of food (which is not very (and spillage) escaping from pans common due to the way hot boxes are used of non-kosher food renders the and the fact that there are usually many layers of trays stacked upon each other), but it is 51 racks, ceiling, and even walls almost impossible for that non-kosher b’liah to get into the kosher food subsequently warmed in the hot box. The significance of this point will cubic inches) and “half” sizes (<20,000 cubic be noted below in footnote 84. inches). Some actual dimensions of hot boxes 52 There is a common misconception that the in these categories are [dimensions are in kashering is accomplished via k’bol’oh kach inches]: polto, which is to say that if the hot box is only Cubic heated via Sternos then it can also be kashered Size Height Width Depth inches with a similar number of Sternos. The fallacy Extra large 59 60 25 88,500 with this is that it is widely accepted that the Large 63 54 23 78,246 concept of k’bol’oh kach polto applies to (a) Medium 57 48 23 62,928 choosing whether libun or hag’alah is required Small 56 43 23 55,384 (Shulchan Aruch 451:4-5), and (b) the level of Full upright 64 19 28 34,048 hag’alah which is required (kli rishon, kli sheini, Half exact temperature) (ibid. 451:5), but does not upright 28 19 26 13,832 apply to the temperature of libun. In other words, libun can only be accomplished when 51 The b’liah into the hot box is primarily via the item reaches a specific objective zei’ah which, of course, rises to render the temperature (regardless of how hot the food ceiling, racks, and upper walls as non-kosher and utensil were when they were used for non-
Page 14 Sappirim which was accomplished by a case where the person put fire putting lit Sternos into the box. or coals directly onto the non- [Details on how many and which kosher surface. If one merely type of Sternos should be used will heats up a chamber then the be noted below in this article.] metal must reach a considerably This article will discuss (a) the OU’s hotter temperature before libun recent decision to no longer allow kal is accomplished. In order to this type of kashering, (b) reasons accomplish libun kal in that why others might suggest a scenario the chamber must different standard as a justification maintain a temperature of 550° F of the original method, and (c) for one hour, 450° F for 1.5 hours, details of how to kasher as per or 375° F for two hours. This is by either standard. no means a “new” position of Rav OU Ruling Belsky’s and was included in what is likely the very first record of As noted, the aforementioned rulings which he gave to the OU method of kashering hot boxes is more than two decades ago.54 an attempt to create libun kal in place of hag’alah. What Until now, the OU55 and others temperature is required for libun assumed that the kashering kal? It is well documented in method outlined above met this earlier Poskim53 that libun kal is standard. However, in recent accomplished when heat is weeks the OU conducted tests applied to a surface until the which showed that when people backside side of that surface performed the “kashering reaches yad soledes bo (~160- procedure” the hot boxes did not 175° F). necessarily reach and maintain
However, Rav Belsky said that those Poskim were only discussing 54 See questions 25-27 in OU Document X-1 which was written circa 1990. 55 See, for example, Section X of the OU’s Commercial and Retail Kashering, authored by kosher), and the utensil is not considered Rabbi Yosef Eisen which was printed in 1993 and “kosher” just because it was heated to a (essentially) recommended this method of temperature which is hotter than the one used kashering for hot boxes (warming cabinets). during cooking of non-kosher food. One reason why people have thought that the 53 Taz 451:8, Magen Avraham 451:27, Gra”z hot boxes met the standard for libun kal is that 451:10, and Aruch HaShulchan 451:5. Earlier many Mashgichim report that during kashering sources for this issue (and others who appear to even the outside of the hot box is exceedingly require a higher temperature) will be noted hot in spite of the fact that the walls are below towards the end of the article. insulated.
March 2012 Page 15 the desired temperature. [Our which they rule that it is sufficient own tests confirmed this.] to heat the utensil until it is yad soledes bo, because that shows Accordingly, the OU announced that the fire’s heat has penetrated a change of policy and will the entire thickness of the utensil. henceforth not allow the However, he reasoned that the kashering of hot boxes.56 Thus, the latter case is one in which those OU’s standard has not changed, Poskim would have demanded a but rather they have become different standard. aware that the common method of kashering does not meet that The reason to disagree with this is standard. that the following early sources for Justification of the Original the use of libun kal in place of Method hag’alah are, in fact, discussing cases that seem quite similar to Libun kal the latter case: We have seen that Rav Belsky’s Gemara, Avodah Zara 33b cites standard for libun kal is based on a machlokes as to whether a a distinction between whether non-kosher wine barrel can be libun kal is performed by placing a kashered by placing burning flame directly onto the surface or into the (קינסא) slivers of wood by warming a chamber without a barrel until the tar melts on the flame touching each surface. He inside. The Gemara’s conclusion based this on the assumption that is that this is not sufficient for the former case is the “standard” kashering because it does not one discussed in the Poskim, in indicate that the heat penetrated the full thickness of 57 56 In the words of Rabbi E. Gersten, writing for the barrel. However, Tosfos the OU Poskim: infers from this that if enough There is a grave concern that when kashering hotel warming boxes this minimum heat would be placed into the libun temperature is not being achieved. barrel so as to render the outer Additionally, it has been reported that those surface of the barrel yad soledes who have strived to reach these libun temperatures have found that they have bo, that would be sufficient to caused damage to the warmers by melting kasher the barrel. the rubber gaskets. Therefore, the OU is instituting that one should not attempt to kasher hotel warming boxes, but rather caterers must bring their own warmers with them to hotels. 57 Tosfos s.v. kinsah.
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The implication is that as long as Thus, this is an example of a there is enough heat inside the chamber being heated by a barrel to penetrate the full flame without direct contact, thickness of the barrel-walls, the and Magen Avraham assumes barrel has been kashered that in the preheating of the regardless of whether the flames oven the walls will surely touch all or any surfaces of the become hot enough to have barrel. undergone libun kal. If libun kal Shulchan Aruch58 rules that if in such situations requires that one places a new (layer onto the walls merely reach yad the) “floor” in an oven, that soledes (on the outer side) we oven can be used for baking can understand why it is matzos for Pesach. We “automatic” that the walls are understand that placing a new kashered during every startup. floor prevents chametz b’lios If, however, libun kal in that case absorbed into the original floor requires a high heat which is from being absorbed into the maintained for an extended Pesach matzah, but what about time, it would seem that the b’lios in the walls and ceiling Shulchan Aruch and Magen of the oven? Magen Avraham59 Avraham should have provided answers that when the oven is directions for this procedure. preheated for the baking of Pesach matzos, that heat will These sources – coupled with the constitute a libun (kal) on the fact that no other Poskim give any oven’s walls and ceiling. indication that there is an alternate shiur for chambers than Clearly, the oven’s flames will for cases where the flame is put 60 not touch every surface, yet directly onto the surface – the oven has been kashered. indicate that in all cases libun kal is accomplished when the full thickness of the metal is heated to 58 Shulchan Aruch 461:1. 59 Magen Avraham 461:2. yad soledes bo. Rav Schwartz 60 Not only is this statement logical, but in fact agreed with this line of reasoning. the beginning of that halacha (Shulchan Aruch 461:1) notes that if one kashers an oven floor If this is the standard which is with coals (instead of putting down a new oven required for all libun kal, then it is floor), he must make a special effort to put most definitely possible to kasher coals on every surface because we assume that otherwise there will not be coals everywhere.
March 2012 Page 17 a hot box with Sternos, as will be Libun kal in place of hag’alah described in more detail below. The source that allows libun kal It was the author’s intention to present to be used instead of hag’alah is the above proofs to Rav Belsky for review so that he could clarify if and why he the Gemara cited above, and disagrees. We continue to be mispallel we have seen that Tosfos that Hashem should send Rav Belsky a refuah sheleimah so that he will have the indicates that the required strength to respond to the above points temperature is yad soledes bo .(on the backside of the utensil) .עבודת הקודש and continue in his other Before concluding this section we In this context, it is noteworthy must address two further questions that after Mordechai62 records – one on the lenient standard this requirement he then notes suggested above, and one on that it is common for people to Rav Belsky’s standard. test this temperature by placing Home Oven a piece of straw on the utensil to If the above analysis is correct, we see if it burns (kash nisraf). The might wonder why it is commonly auto-ignition temperature of accepted that the method of straw is considerably higher than kashering a home oven is to turn yad soledes bo,63 and thus the the oven on to 550° F and leave it test was clearly a chumrah over at that temperature for an hour. the technical requirement of the [This method is attributed to Rav halacha. Aharon Kotler.] Why must the - Libun kal in place of libun gamur oven be so hot and be on for so long? Does that not indicate that libun kal for an oven chamber differentiates between the different types of libun kal (although we do not follow all details requires more than merely heating of the positions presented there). The the metal to yad soledes bo? difference between the types of libun kal will also explain why Gra”z provides different shiurim for libun kal in 451:10, 451:16, 451:38 & 451:70. In order to answer this question we 62 Mordechai, Avodah Zara 860. His words are עד שתהא יד סולדת בו משני עבריה והם רגילים לבדוק על ידי must first review the little known Possibly] .נתינת קש עליה מבחוץ לראות אם הקש נשרף fact that there are actually two the reason they tested with straw instead of was just to avoid (יד סולדת method of kashering known as their hands (for 61 burning themselves.] “libun kal”: 63 Yad soledes bo for these purposes is assumed to be approximately 160-175° F, while the auto- ignition temperature of straw is approximately 61 In addition to the details provided in the text 300-400° F (http://bit.ly/yGWQmG) (although others claim it is 500-600° F – see דיני ) that follows, see Pri Megadim MZ end of 452 .(in the libun section) who http://bit.ly/Az7m1E וסדר ההגעלה בקצרה
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The Gemara64 says that libun is chumrah, as follows: The walls accomplished when the utensil’s and ceiling of a home oven are surface begins to peel or when made of a material called sparks begin to fly from it, but “porcelain enamel”, which is glass Hago’os Maimonios65 suggests fused onto metal. [In addition the that this is somewhat of an window in the oven’s door is exaggeration and the true made of glass.] Since the requirement is that the utensil Ashkenazic custom is to be reaches the temperature where machmir and treat glass like straw would burn on it. Although cheress,67 the oven walls and door the halacha does not accept must be kashered with libun. this latter opinion, Rema66 rules However, since it is only a that in situations where the chumrah to consider glass as requirement to perform libun is a cheress, one may satisfy mere chumrah we may be themselves by kashering those satisfied with this lower level of surfaces with libun kal which takes libun. the place of libun gamur (as per In this case, kash nisraf is not the Hago’os Maimonios). test for libun kal but is rather the actual required temperature [Another case where the higher level. This is in contrast to the first level of libun kal (i.e. kash nisraf case where libun kal merely rather than yad soledes bo) is replaces hag’alah. required is where one is using libun kal to incinerate small amounts of A home oven is an example of an residue found on a utensil (Rema item which requires libun as a 451:4). Whether this occurs by heating a chamber to kash nisraf temperatures or whether self- cited (תשיר קליפתו) Gemara, Avodah Zara 76a 64 in Mishnah Berurah 451:29, and Yerushalmi, cleaning temperatures of 800- cited in Shulchan 1000° F are necessary, requires (ניצוצות ניתזין) Avodah Zara 5:15 Aruch 451:4. Nowadays, when metals do not further study.] exhibit these signs (possibly because they are refined more thoroughly than in earlier centuries), it is common to judge that metal has Therefore, a home oven must be undergone libun gamur when it glows red hot, as noted in Teshuvos Maimonios, Hil. kashered with a much higher Ma’acholos Asuros #5 (R’ Chaim Chernoff). temperature than a hot box as it is 65 Hago'os Maimonios to Rambam, Hil. made of different materials. The Ma'acholos Asuros 17:3 note 5, cited in Beis Yosef 451 page 194a. 66 Rema 451:4 as per Pri Megadim AA 451:22. 67 Rema 451:26.
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home oven requires kash nisraf, since it is made of glass, a In tests that we conducted we material that requires libun kal as found that if paper was placed libun, and the hot box can be into an oven which was kashered with yad soledes bo preheated to 550° F the paper since all it requires is (libun kal as) was blackened and burnt within hag’alah. 10 minutes. Thus, it seems that the Kash nisraf temperature common practice to kasher a home oven by putting it at 550° F The discussion of home ovens and for an hour is a way of assuring the temperature required to that the entire thickness of all kasher them raises another parts of the oven walls are truly question on Rav Belsky’s heated to that temperature. approach. Rav Belsky essentially
holds that in order to kasher a In contrast, most paper placed chamber heated without a direct into an oven at 375° F or 450° F did flame on the surface, the utensil not show any signs of being burnt must reach a temperature of kash even after being in the oven for nisraf, and that this can/should be the designated 1.5-2 hours or measured with paper.68 69 longer. The paper did show signs of browning the longer it stayed in 68 In explaining how the temperatures for kashering an oven were determined, Rav Belsky the oven, but (a) there was no told this author (OU Document K-203) that: clear difference between paper …one can perform “libun kal” even without a direct flame by heating the utensil/oven that was in the oven for the until kash is nisraf on it because that also specified amount of time as shows that the fire has penetrated the opposed to paper that was in for thickness of the utensil. Kash nisraf is the proper barometer for this because just like longer or shorter,70 and (b) some paper burns up immediately when fire is paper that was in the oven for the place on it, we can reason that once paper/kash burns on a utensil the fire is specified amount of time having the same effect as a flame. The Poskim tested this and noticed that if paper is placed in an oven then at 550 degrees it 70 See the pinwheel-shaped picture of papers takes only an hour for the paper to burn but shown in graduated color. The actual order of at lower temperatures (450° for 1.5 hours or papers in this pinwheel – from lightest to darkest 375° for 2 hours) it is a slower process and – are as follows: [Letters represent the different takes much longer. time and temperature (see the pictures) and 69 It is well known that paper auto-ignites550° F – 10 at 451° those marked with a star (*) were in the oven for minutes F which is somewhat higher than the auto- long enough to meet Rav Belsky’s libun kal ignition temperature of straw (see footnote 73), requirements.] C, C, C, C, F*, F*, F*, C, A*, D, D, but presumably the use of paper for this test is A*, F*, A*, A*, F*, D, A*, D, D, B*, G*, G*, B*, B*, B*, .*G*, B*, G*, E, G*, E, E, G*, G .לחומרא לא דק an example of
Page 20 Sappirim appeared to undergo very little bo. Let us now consider methods change at all. of kashering (or using) hot boxes which would satisfy these standards. Alternatives 375° F – 10 minutes 450° F – 10 minutes As noted, the OU suggested that people should not kasher hot boxes but rather each caterer should bring his own dedicated 375° F – 1.5 hours 450° F – 2 hours kosher hot boxes to each event. This will work for many situations but will make things quite difficult for (a) certain groups, such as 375° F – 2.5 hours 450° F – 2.5 hours NCSY, who “self-cater” events in Thus, the widely accepted remote locations far away from practice of considering 550° F (for kosher caterers, and (b) hotels an hour) to be considered kash which want to be kosher for nisraf seems to be firmly based on Pesach. In each of these cases, a meaningful occurrence, but it is the requirement to own, store, not clear what the basis is for and bring kosher hot boxes to the suggesting that kash nisraf occurs event will be a particular hardship. at 375° F or 450 ° F, even if the chamber is “held” at that Others have suggested that temperature for an extended alternate methods of kashering time. be used: Kashering a Hot Box Some propose using a blow torch on all surfaces, but this is We have seen that there are two only reasonable for (a) possible standards for kashering a Mashgichim and facilities which hot box; Rav Belsky says that the are comfortable using a torch hot box must be 550° F for an on equipment, and (b) hot hour, 450° F for 1.5 hours, or 375° F boxes that have no gaskets for 2 hours, and the lower (because gaskets will melt if standard would only require that touched by the torch’s flame). the hot box’s interior surfaces be heated until (the back side of) Others might use a steam jenny those surfaces are yad soledes or put pans of hot water into the
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hot box (with Sternos) so as to reached 400-450° F and accomplish a hag’alah. For this maintained that temperature for to qualify as hag’alah, the 30 minutes, and it seems that if we steam would have to condense were more particular about the on the ceiling and walls of the number and type of Sternos used hot box;71 if this was done we could easily reach 450° F and correctly it would be a suitable maintain that temperature for 1.5 kashering. hours (and possibly even reach Lastly, a suggestion was made 550° F), as discussed below. that food be covered when put Fuels into the hot box. This would A study of more than 20 types of entail putting a layer or two of Sterno-like chafing dish warmers foil on the shelves/racks and manufactured by a half dozen some cover over the top layer of manufacturers showed that they pans or plates in the hot box. all72 use one of three fuels: This would prevent b’lios ethanol, methanol, or diethylene absorbed in the hot box from glycol (DEG). [Some use ethanol entering the kosher food. with a bit of methanol mixed in.] Sternos Of those fuels: It would seem that The first two are gels, while DEG the simplest is used as a liquid with the flame suggestion would be on a wick. to merely modify the Ethanol consistently provides the original method of most BTU73 per hour (i.e. the most kashering in a heat), closely followed by manner that Hot box at 450° F methanol.74 In almost every accomplishes the during kashering requirements of either standard above. In our testing using Sternos for kashering, different hot boxes 72 One exception that was found was that the liquid CandleLamp is made of a “proprietary blend of glycols” which contains 0% DEG. 71 If non-kosher flavor is absorbed purely via 73 BTU = British Thermal Units, a standard method steam, then the hot box could be kashered with of measuring energy by the amount of water it .can heat כבולעו כך פולטו steam based on the principle of (Maharsham 1:92). However, if the non-kosher 74 Based on information provided by four steam had condensed into liquid those areas manufacturers, the average BTU per hour in would have to be kashered with water (i.e. Sterno-like canisters was 1,767 for ethanol, 1,463 condensed steam) that is at a hag’alah for methanol, and only 866 for DEG (or 1,021 if temperature (based on Iggeros Moshe YD 1:60). one includes the double-wicked DEG canisters).
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case,75 the liquid DEG provides they rest. In contrast, DEG burns considerably less BTU than the on a wick that is suspended others. above the canister, such that The canisters made by different the floor underneath the manufacturers provide different canister will not get amounts of BTU per hour and hot/kashered. total BTU.76 These differences depend on the amount and Thus in choosing a Sterno for use in percentage of fuel in each kashering, one should definitely canister,77 the size of the not use a DEG/liquid/wicked 79 canister’s opening,78 and (likely) canister. It would be best to use other factors. an ethanol-based gel, and a second choice would be to use Since the 80 One should one that is methanol-based. Of ethanol and definitely not the ethanol-based gels, the ones methanol burn kasher with a we are familiar with that provide without a wick, canister fueled the highest amount of BTU per the canister by diethylene glycol (i.e. hour are the Sterno brand, and that holds them liquid, wicked) the FancyHeat brand (red or becomes hot, green).81 and that heat spreads to the floor upon which Number of Sternos Many seasoned Mashgichim feel 75 The exception was that in some DEG canisters comfortable judging how many that come with two wicks the fuel burnt so Sternos to use when kashering a quickly as to provide more (or equal) BTU per hour than the gels. It is also worth noting that a hot box, but for the purposes of particular popular DEG canister which is billed this article – and in particular, for as being particularly “hot”, does in fact burn considerably more BTU per hour than other DEG those who want to satisfy Rav canisters (~1,300 vs. ~800-900 for most others) Belsky’s higher standard of libun but is still only about 2/3 the strength of the best kal – we made a more formal ethanol canisters. 76 There was a surprisingly wide range of BTU per canister. In approximately 20 varieties the BTU 79 The two reasons for this are, as noted, that (a) per hour ranged from 778-1,966 and the total DEG generally provides fewer BTU per hour, and BTU in the canister was 1,430-5,460. (b) the can (and area below it) do not get hot. 77 The liquid/wicked products were (basically) all 80 The range of BTU per hour for methanol-based 100% DEG, and the range of percentages of the gels (for those that shared information with us) primary ingredients in different canisters was was 1,430-1,530. ethanol – 65-78%, and methanol – 70-75%. 81 The Sterno brand ethanol canisters claim to 78 The standard opening size (for gels) is 2 provide 1,966 BTU per hour, and the FancyHeat inches. An opening of a different size would (red and green) canisters claim to provide 1,840 allow for fuel to burn at a different rate. BTU per hour.
March 2012 Page 23 calculation of how many Sternos box tended to drop towards the are required.82 Based on the goal end of cycle, such that there of heating the chamber to 450° F would likely be only about an hour in approximately 40 minutes,83 at 450° F]. Accordingly, we and under the assumption that a recommend that those who person is using one of the Sternos would like to fulfill the OU recommended in the previous requirements should insert a section, we advise the following: second set of lit Sternos into the
Cubic Ethanol Methanol hot box towards the end of the 2 Hot Box Size Inches Sternos Sternos hours and wait until this second Extra large >80,000 10 12 set burns out before declaring the Large 70-80,000 9 10-11 hot box to be kashered. Medium 60-70,000 8 9 Small <60,000 7 8 Position of Sternos Full upright 20-40,000 6 7 Many Mashgichim randomly Half upright <20,000 3 3-4
For more details on the sizes of hot boxes used in the above chart, see footnote 50. scatter the Sternos around the hot box during kashering. In our The recommended Sternos each testing of this procedure we burn for approximately 2 hours, noticed that when this was done and for those who want to satisfy there were two areas that did not the OU’s requirements of having a get as hot as the others. Those temperature of 450° F for 1.5 areas were the bottom part of the hours, the aforementioned hot box and the floor space near recommendations would fall just the door. The reasons for this and short of that amount of time. [In the proposed solutions to these addition, in our testing we noticed concerns are presented in the that the temperature of the hot chart below: Area Reason Solution Bottom 1/4 of the Heat rises Place all 82 A good portion of the calculations were hot box walls Sternos on the based on formulas and charts presented on floor of the hot pages 141-151 of the HotWatt 2010 Catalogue box which can be found at http://bit.ly/wz7owi. The Floor space Ambient Place 2-3 of calculations considered the energy required to between the temperature air the Sternos heat the chamber and the heat lost through Sternos and the leaking in from near the the insulation and from the door. door84 the door door85 83 The time and temperature were chosen because they were not only reasonable choices that could be accomplished without apparent fear of ruining the gaskets, but were 84 It was noted in footnote 51 that it is not clear also simultaneously in the range of Rav Belsky’s that there is truly a need to kasher the floor of libun kal requirements. the hot box. The procedures in the text are
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1. Clean the hot both A related complication of thoroughly, and do not use it for kashering a hot box is that if the 24 hours.86 door is open at all, hot air will be 2. Calculate the correct allowed to escape, but if the door number of 2-hour ethanol or is sealed shut then no oxygen will methanol Sternos (preferably enter the box, and the flames will ethanol-based canisters of the be extinguished. The proper Sterno or FancyHeat brands) compromise for this conundrum based on the size of the hot box. appears to be that if the hot box [Liquid diethylene glycol has gaskets around the door canisters should not be used.] (which would seal it well) then the Cubic Sternos Methanol door should be left open slightly Hot Box Size Inches Needed Sternos Extra large >80,000 10 12 during kashering, and if the door Large 70-80,000 9 10-11 does not have gaskets then it Medium 60-70,000 8 9 can/should be tightly closed (and Small <60,000 7 8 enough oxygen will leak through Full upright 20-40,000 6 7 the door to maintain combustion). Half upright <20,000 3 3-4 3. Put Sternos into the hot box, Kashering Procedure (Summary) placing 2-3 near the door. Based on the information presented above, the following is 4. Light the Sternos, and close the recommended procedure for the hot box’s door. kashering a hot box: - If there is no gasket around the door, close the door tightly. - If there is a gasket around the door, leave the door open very slightly.
written under the assumption that the entire floor does require kashering. 85 Some Mashgichim attempt to solve this concern by emptying gel from a Sterno and placing the gel directly onto the floor of the hot 86 Although it is generally accepted that the box. This procedure raises serious safety letter of the law is that one may perform libun concerns (in addition to the inability to properly kal even if the item is ben yomo (implicitly judge the correct amount of gel to use, and the rejecting the idea considered by Pri Megadim fact that “loose” gel will burn considerably MZ 452:4), it is also prudent for all kashering to faster than gel in a can) and we therefore do be performed when equipment is aino ben not recommend this practice. yomo (along the lines of Rema 452:2).
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5. Keep the door closed until all Sternos have burnt out (and have had a chance to cool off). 6. Those wishing to kasher hot boxes according to the OU standard should do as follows, approximately 1.5 – 2 hours after Step 4 is performed: - Extinguish approximately half of the original Sternos - Add a second set of Sternos to the hot box as per the following chart: Ethanol Methanol Hot Box Size Sternos Sternos Extra large 8 10 Large 7 8 Medium 6 7 Small 5 6 Full upright 4 5 Half upright 2-3 3 - Place 2-3 of the new Sternos near the door, light the Sternos and close the hot box’s door (as above). - Light the Sternos and close the hot box’s door. - Keep the door closed until all Sternos have burnt out (and have had a chance to cool off).