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Hatmana (Insulating) Food Going into Shabbos 4 – Hot Material Which Lose Their Heat – (Klal 2 Siman 5) Erev Shabbos- S0050

D'var Halacha
D'var Halacha
Hatmana (Insulating) Food Going into Shabbos 4 - Hot Material Which Lose Their Heat - (Klal 2 Siman 5) Erev Shabbos- S0050

 We are continuing in siman 5, discussing the halachos of hatmana. The Chayei Adam moves on to the following question. We know that hatmana with a mosif hevel is assur even before Shabbos, but hatmana with a maamid hevel is muttar before Shabbos. What do we consider something which adds heat, but, as time goes on, the heat dissipates? We learned (S0048) that the concern with hatmana is that once a person can perform hatmana on Shabbos, they may come to realize their food is not as hot as they would like, and will stir the coals to make it hotter. Over here, since the person performing the hatmana is aware that the insulation will cool off, are we able to assume that the person is not interested enough in the heat that they may come to stir the coals, or are we still concerned?

The Chayei Adam discusses an example which is not so relevant, but will have important implications for us. He uses the example of an oven. Even if a person removes the coals from the oven before Shabbos, the oven still generates significant heat and certainly is mosif hevel. However, at some point it cools down and is no longer mosif hevel. This situation is a machlokes rishonim. Nevertheless, the Chayei Adam says that meikar hadin, it is muttar, meaning, we consider this case maamid hevel since the heat eventually dissipates. We assume the  the person performing the hatmana is aware that the insulation will cool off, so if they employed this item as their insulator, they must not be interested in the food getting any warmer.

 The Chayei Adam points out that in the case of an oven, there is no hatmana at all, (even without the heter of sealing the oven).  And, at worst the oven is considered hatmana b’miktzas (S0049).

  The Chayei Adam continues to discuss insulating a point of  coffee. As we explained,  their ovens were shaped like a cone, in that they were larger on the bottom and smaller on the top. The bottom was open and attached to the ground, using the ground as the floor of the oven. The top was open with a much smaller hole in order to allow for smoke to escape. There would be an opening on the side as well, in order to insert the food. When they would prepare coffee, they would dig a small hole in the floor of the oven, keep it inside, and cover it in blankets in order to keep their coffee warm. It is on this scenario, in which the coffee is fully insulated, that the Chayei Adam still paskens that one can be meikil and consider the oven only a maamid hevel, since the heat in the oven will eventually dissipate. 

According to the poskim who are machmir, one can still solve the problem by making sure the coffee only receives hatmana b’miktzas, either by removing some of the clothing, or placing a board on top of the pot so that when the blankets are draped over the pot, they do not touch the pot directly. 


  • A davar mosif hevel cannot be used for hatmana even before Shabbos
  • A davar maamid hevel can be used for hatmana before Shabbos, but not on Shabbos itself.
  • Hatmana is defined as when the insulating item directly touches the pot and fully covers the pot. If these two conditions are not present, it is considered hatmana b’miktzas, and is muttar for Ashkenazim. Sephardim are still machmir if the insulating material is mosif hevel.
    • Placing food in a warm oven before Shabbos (without any heat source present) is not considered hatmana, because even though it is mosif hevel at the onset of Shabbos, the heat eventually dissipates.


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