Which substances are classified as adding heat (mosif hevel) and which do not?
Synopsis
The Mechaber lists specific substances that add heat (always: olive waste, sesame waste, manure, salt, lime, sand; when wet: straw, grape refuse, soft materials, grasses) and those that do not add heat (clothing, fruits, feathers, linen fibers, wood shavings). The Rema permits insulating with rocks despite their adding heat, since this is an uncommon practice.
More in Insulating Food (Hatmanah)
May one insulate (hatmanah) food on Shabbat itself with a substance that does not add heat?
4 opinions
May one insulate food before Shabbat with a substance that adds heat (mosif hevel)?
12 opinions
If food was insulated in a heat-adding substance and it merely retained its warmth (did not heat up or improve), is it permitted b'dieved?
2 opinions
May one place items on top of food on Shabbat to protect it from mice or dust, even if those items retain heat?
3 opinions
If hatmanah was done before Shabbat and the pot became uncovered on Shabbat, may one re-cover it or change the insulation?
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If food is transferred from its original pot to a different pot on Shabbat, may one insulate it?
4 opinions
May one insulate cold food on Shabbat, and with what types of substances?
3 opinions
Does the prohibition of hatmanah apply even when food is fully cooked and mitzta'mek v'ra lo (shrinks to its detriment)?
6 opinions
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