Communication of impurity in a rooved structure, into the contents of a receptacle
Ability of a clay or non-clay receptacle to prevent external impurity from affecting its internal contents, where the opening of the receptacle is outside of the rooved structure: Zevachim 3a, 3b
Ability of a barrier inside a rooved structure to prevent impurity from passing from one side of the barrier to the other: Zevachim 3a
A wood vessel which is not designed to be mobile is considered a barrier within a structure: Megillah 26b; Zevachim 3a-b
Status of a jug which has been punctured and then plugged with straw: Zevachim 3a-b
Status of food which is coated with clay: Zevachim 3b