818. Kashering a Barrel

116:8 Kashering a barrel is done as follows: stones are heated until they glow and they are placed in the barrel. Boiling water is poured on the stones directly from the vessel in which it was boiled and the barrel is rotated so that the boiling water will be able to reach every spot. If a barrel is made of staves held together by iron hoops, and if the barrel held chometz like brandy or flour, then immersion in boiling water is not effective to kasher it.

116:9 If something requires immersion in boiling water to kasher it, then peeling off the outermost layer will not suffice (because absorption occurs throughout - Mishnah Brurah 451:26); it must be immersed in boiling water.