To purchase this Sefer, click here
9. The law if one transgressed and insulated in material which adds heat:
First Opinion: If one transgressed and insulated [in material which increases heat], even [if this was done] inadvertently [without prior knowledge of the prohibition], [nevertheless] the food is forbidden both to him and to others until after Shabbos. [See Q&A 1] [However this only applies] in a case that the added heat to the food made it condense in a way beneficial to it, or if the food was cold and got heated through this insulation. However, if it remained the same temperature as it was originally, and it’s a food [which has been cooked to the point] that further cooking will cause it to condense in a way detrimental to it, then it is permitted [to be eaten on Shabbos], being that there is no benefit being gained from having done the prohibition.
Second Opinion: [Food which is cooked to the point of Ben Drusaiy, or which contains raw meat entered right before Shabbos, or which is designated to only be eaten the next day, may even initially be insulated before Shabbos with material that adds heat. See above, Halacha 2, for full content of this opinion].
The Final Ruling regarding food designated for the next day: One may not [initially] rely on the latter opinion [who rules that food designated for the next day may be insulated before Shabbos with material that adds heat], unless it is already after the fact [in which case one may rely on them] as long as this does not occur on a regular basis.
The Final Ruling regarding food cooked to Ben Drusaiy and raw meat: [Admur does not make clear mention regarding the law if one went ahead and insulated food cooked to the point of Ben Drusaiy, or food which had raw meat placed in it right before Shabbos. See Q&A for the final ruling on this matter.]
If one insulated food which has been cooked to the point of Ben Drusaiy, may he be lenient like the opinions that permit this, and thus be allowed to eat the food on Shabbos?
Opinion of Rav Farkash: If the food was fully cooked before Shabbos, even if further condensing is good for it, then if the insulation was done by mistake or due to lack of knowledge of the prohibition, one may be lenient to eat it on Shabbos. However if the food was not fully cooked, but was cooked to the point of Ben Drusaiy, then one should not eat it on Shabbos, unless it is a pressing situation.
If one transgressed and insulated food with a heating material is the food permitted immediately after Shabbos, or does one need to wait until enough time passes for it to heat up?
The food is forbidden until enough time has passed after Shabbos to be able to have heated it.
The food is prohibited until after Shabbos unless either:
1. The food was already cooked to the point of Ben Drusaiy. [According to Rav Farkash this is allowed only if it is a pressing situation. If the food is fully cooked then one may be lenient even in a non-pressing situation.] If it is fully cooked and further cooking is detrimental to the owner and it is still warm, it is allowed to be eaten according to all.
2. One insulated right before Shabbos raw meat with material that adds heat. [According to Rav Farkash this is allowed only if it is a pressing situation].
3. Before Shabbos one insulated food that he does not plan to eat until the next day with material that adds heat. However, if this is a recurring matter then one may not eat the food on Shabbos.
 Admur 257:1
 This ruling goes in accordance with the ruling of the Michaber, the first opinion mentioned in Halacha 2 above, that it is forbidden to insulate foods even if they are fully cooked. However according to the other opinions mentioned above foods which are cooked until Ben Drusaiy may even be initially insulated before Shabbos. Admur does not mention in his final ruling what is the law if one Bedieved insulated cooked food. Regarding the final ruling see Q&A 1.
 One should immediately remove the food from the insulation. [Shabbos Kehalacha Vol. 2 page 7]
 Meaning that if he has already insulated food for Shabbos day in material which adds heat, one may be lenient to eat this food on Shabbos. To note that according to the Michaber all the above is forbidden even after the fact.
 Shabbos Kehalacha Vol. 2 pages 12-15
 The Rama clearly rules that when insulated Beshogeg it is permitted, however the Magen Avraham limits this to only of the food has been fully cooked. While the Taz argues completely on the Rama and says that it is always forbidden. The M”B rules like the Rama in this, however argues on the Magen Avraham as will be brought in the next note.
 The Mishneh Berurah as well as the Chayeh Adam and other Poskim all rule that by time of need one may be lenient if the food had already been cooked to the point of Ben Drusaiy.
Regarding the opinion of the Alter Rebbe in all this: On the one hand he completely omitted this ruling of the Rama to be lenient Bedieved, and only brought that there are some people which are accustomed to do so initially, and did not go into at all what is the law if Bedieved it was done. However, on the other hand, it seems that it is included in the latter ruling regarding food insulated for the next day, that Bedieved one may be lenient, as the wording there is “There are those who are even furthermore lenient…” implying that if even in this case we are lenient after the fact, then certainly in the previous case. However nevertheless, one cannot innovate a Halacha based on these inferences, and thus one should not allow it to be eaten unless there is a pressing situation, in which case there are many Poskim which permit it.
[Now, although in 253:24-25 Admur rules that after the fact we only prohibit food if a prohibition was done according to all opinions, and thus here too since this matter is a dispute it should be permitted Bedieved according to Admur. Nevertheless, this can not necessarily be used here as a proof as a) Despite this law that in case of dispute Bedieved we are lenient, we find that Admur himself rules at times to be stringent even Bedieved. [see 318:9]; b) Admur himself limited his ruling regarding food designated for the next day that one may only be lenient Bedieved if it is not occur often, thus showing that he does not take the previous mentioned rule into account in this case of dispute.]
The above is all in accordance to the opinion of Rav Farkash in Shabbos Kehalacha. For other opinions in Admur see Q&A above.
 See Kitzur Halachos Shulchan Aruch Admur 257:7 footnote 16.
 As this is the simple implication of Admur in 257:1 which seems to include Ben Drusaiy foods in the Bedieved leniency. As well it follows the rule in 253:24 that by all cases of dispute we are lenient Bedieved.
 Shabbos Kehalacha Vol. 2 pages 9-10
 The Ketzos Hashulchan adds in parentheses that the food is forbidden until enough time has passed after Shabbos to be able to have heated it. However seemingly this only applies if one insulated food before Shabbos. However, if one insulated food on Shabbos, then it would be permitted immediately after Shabbos, based on the rule explained in chapter 318 regarding this. [Seemingly this is the reason that the Alter Rebbe did not write that it is forbidden until enough time has passed after Shabbos, being that he wanted to state the Halacha in accordance to all scenarios.]
 Based on the rulings mentioned in the Q&A above.
 Chapter 257 Halacha 1,
 All the below mentioned scenarios are disputed if allowed to be done even initially, and thus we are lenient after the fact to not prohibit the food on Shabbos [and at times this leniency is only in pressing situation, as explained above].
 See Q&A above
If on Erev Shabbos one insulated the food with a material that adds heat but the food had been cooked to the extent that further condensing is damaging for it and the food did not become hotter, but rather retained its temperature then it may be eaten on Shabbos according to all opinions [meaning even according to the Michaber], as there is no benefit gained from the prohibition. However, if the food is not fully cooked then according to the Michaber it is not allowed on Shabbos.