Halacha » Libun

Libun

Libun means heating the utensil to the temperature that, if it were made of iron, the utensil would release sparks (שו”ע או”ח תנא:ד, ע”ע לבושי עוז פח:ו). This is usually referred to as libun gamur. Libun needs to be this hot even if the beliot were not absorbed at such high temperatures, because libun works by burning up the beliot. It does not have the rule of k’bolo kach polto. (There are several leniencies in regard to libun which are discussed in other Halacha Articles.) There is a dispute amongst the Rishonim what the level of heat is for libun. Most Rishonim rule that it means heating to the level that sparks fly off the metal, and this is how the Shulchan Aruch defines libun. The Mordechai learns that libun means heating to the point that if straw were to touch the utensil, the straw would get singed. The Rama (או”ח תנא:ד) writes that we can rely on this libun kal in some situations, which will be discussed in other posts.

Practically, libun is done by heating the utensil to between 660-750 Fahrenheit. Even though sparks don’t come out at those temperatures, the Poskim explain that in the times of the Talmud the utensils were uneven and had little nicks in them. Those nicks retained particles of food that would combust into small sparks when libun was done. In our pots, which are smooth, those sparks won’t appear, but libun is still accomplished at the temperatures that would have induced those sparks in the times of the Talmud. Libun kal is done by heating the utensil to between 390-480 Fahrenheit, which is the temperature that a piece of straw or tissue held to the utensil would start to singe.

Rav Yisrael Belsky quotes an explanation from Rabbi Yaakov Kamenetzky why our libun works even though we do not see our pots turn red hot, nor do they emit sparks. Rabbi Kamenetzky said that only iron will emit sparks when heated to the temperature of libun, but not the alloys which we use today. Therefore, even though our metal does not emit sparks, it is still considered a proper libun when heated to the temperature at which iron emits sparks.