The following utensils protect with a sealed cover: Dung utensils, stone utensils, clay utensils, earthenware utensils, nesser utensils, bones of a fish or its skin, bones of a sea creature or its skin, and wooden utensils that are tahor. They protect both from their mouths and from their sides, [and] whether they are resting on their bases or tilted on their sides. [If] they were turned over upon their mouths, they protect all that is beneath them down to the depths; R’ Eliezer rules it tamei. [These utensils] protect all things, except for an earthenware utensil, which only protects foodstuff and earthenware utensils.

With what may we surround [the utensil]? With plaster or with gypsum, with pitch or with wax, with mud or with excrement, with mortar or with crushed shards, or with any substance that can be smoothed. We may not surround [a utensil] with tin or with lead, since they cover but do not seal. We may not surround [a utensil] with a fat pressed fig or with dough kneaded with fruit juice, so that it does not come to be disqualified, but if one did surround [with food], it has protected [the utensil].