4:1 The Principle

In Section 2:9 we explained the general principle of Bishul Achar Bishul. For review purposes:


Regarding liquids, “Yesh Bishul Achar Bishul BeDavar Lach” — “there is cooking after cooking with a liquid.” Once a liquid has totally cooled, further reheating is an act of Bishul. However if the liquid has not cooled fully but remains warm enough to be considered a warm/hot liquid (even though it is not Yad Soledes), Bishul does not apply.


Regarding cooked solids, we apply the rule “Ein Bishul Achar Bishul BeDavar Yavesh” — there is no cooking after cooking with a dry solid.

4:2 The Definition of Lach and Yavesh

In this section, it is necessary to define clearly what is considered “Lach” and “Yavesh.”

A food is considered Yavesh when it is totally dry.1 If it is wet to the touch it may not be considered a Davar Yavesh. Even if the majority of the food is dry but there is part of the food that is wet to the touch, it is not considered a Davar Yavesh.2

For example, if one wished to place cold lokshen into hot soup in a Keli Rishon that has been removed from the fire, one must be sure that the lokshen is dry to the touch.

However, one may definitely either: a) place the lokshen into hot soup inside a Keli Sheni; or b) place the lokshen in a bowl and pour hot soup into the bowl using a ladle that has ladled the soup out of a Keli Rishon, even if the lokshen was wet to the touch.3

4:3 Food out of the Freezer

If a Davar Yavesh was taken out of the freezer and it was covered with a layer of frost, it may not be heated to Yad Soledes Bo.4

4:4 A Davar Yavesh that Melts

The rule of Ein Bishul Achar Bishul BeDavar Yavesh only applies to a dry solid that remains a solid. However if upon heating, the dry solid turns into a liquid, then it has the status of a liquid and is subject to Bishul due to the rule of Yesh Bishul Achar Bishul BeDavar Lach.5

For example, one may not pour hot water from a Keli Rishon onto sugar, soup powder, infant formula, etc. Although all these are items that have already been cooked and are now a dry solid, since they dissolve when mixed with the hot water, they are to be considered as a liquid and we apply the rule Yesh Bishul Achar Bishul.6

4:5 Nolad

Certain foods contain fat that gels when the food cools. When such foods are reheated, the gel dissolves and melts. In addition to the problem of Bishul, there is also in this case the question of Nolad — Creating (i.e., bringing a new entity into existence7).

The question of Nolad exists even if the food is reheated less than Yad Soledes Bo.

The rule of Nolad is as follows:8

A fatty food which when heated releases a substantial amount of liquid fat which can be seen, may not be heated on Shabbos. If however the fat is absorbed within the food (e.g., in the case of a pie where the oil is absorbed within the pastry) or even if the food does emit a small amount of oil, it is permitted to be heated.

Therefore practically speaking:

a) If one has a piece of cold cooked chicken or meat around which has gelled some of its liquid, then it may not be reheated on Shabbos.

b) A dry kugel that may emit a small amount of oil may be reheated.9

c) One may not add fat to a soup, even if it is a Keli Shlishi and even if it is not Yad Soledes since the melted fat will be noticeable in the soup.10

d) One may place shmaltz on rice that is not Yad Soledes Bo: since the food absorbs the fat, there is no problem of Nolad. However this would not be allowed on a more solid food like a piece of roast meat upon which the melted fat is clearly visible.

e) There are those who are stringent and do not place a cold piece of chicken (around which has gelled some of its liquid) on the same plate as hot, thick cholent, as this may pose a question of Yesh Bishul Achar Bishul.11

4:6 Butter and Margarine

Butter and margarine that melt with heat are to be considered a liquid and the rule of Yesh Bishul Achar Bishul applies. Therefore, one should not add butter or margarine to mashed potatoes in a Keli Sheni that is Yad Soledes Bo.12 Some Poskim are of the opinion that they may be added to a Davar Gush in a Keli Shlishi.13

4:7 Adding Salt

Even though there are different types of salt: koshering salt, kitchen salt, table salt, etc., we shall refer here only to table salt that has undergone a cooking process before it was crystallized.14

Since salt dissolves upon contact with a liquid, it must be treated as a liquid and Yesh Bishul Achar Bishul. Therefore salt may not be added to a Keli Sheni.15

However, one may pour from a Keli Sheni (Irui Keli Sheni) onto salt, or add salt to a Keli Shlishi.

4:8 Bishul Achar Afiyah — Cooking After Baking

In Section 2:9 we explained that cooking and baking are considered two separate processes, each independently prohibited. Therefore an item that has already been cooked may not be baked, and food that has been baked or roasted may not subsequently be cooked.16

One should be stringent in this matter even in a Keli Sheni; for example, one may not put challah or matzah into soup in a Keli Sheni.

However one may pour from a Keli Sheni onto a baked food, and certainly place a baked food into a Keli Shlishi.

Regarding soup croutons — the halachah depends on how they are manufactured. If they were baked, they may not be placed in a Keli Sheni. If they were deep-fried, which has the halachic status of being cooked, they may be placed in a Keli Sheni.

In practice, if one wishes to add challah, matzah, soup nuts etc., to soup on Shabbos, one should make sure the soup bowl is a Keli Shlishi.

4:9 Afiyah Achar Afiyah — Baking After Baking

There is no baking after baking, i.e., once a food has been baked, it is not subject to further baking.


a) One may heat up a frozen challah (that does not have any frost on it) [see Section 8:3].

b) One may put hot mashed potatoes on a cracker.17