Mishnayos Keilim Perek 3 Mishnah 5

כלי חרס הבריא – that is not shattered or broken.

מטמאין – if the vessel is defiled from its airspace, food and liquids that came in contact with its plaster are impure, because it is considered like the vessel itself (according to Rabbi Shimon and Rabbi Meir).

הטופל את הבריא טהור – that specifically the vessel that is shattered that needs that plastering, that one (i.e., the vessel) is where the plastering is like the vessel and the foods that came in contact with it are defiled when the vessel is impure. But the plastering of a healthy/whole vessel is not considered like a vessel. And the Halakha is according to the Rabbis.

וכן בחידוק קרויה (the lining of a pumpkin that has been hollowed out – to be used as a drawing vessel – i.e., the earthen vessel or clay that has been fitted as a protection) – just as Rabbi Meir and Rabbi Shimon disputed with the Sages with the plastering of a whole vessel, so they disputed with regard to the lining of a pumpkin that has been hollowed out, and this is a dry and hollow gourd that they draw water with, and they regularly fasten around it in a circle of wood or of iron in order that it would not break if it is corked with a stone. For Rabbi Meir and Rabbi Shimon who make unclean the plastering of a whole [earthenware vessel] (i.e., unbroken or unshattered) also make unclean even this, and even if it was a pure pumpkin-shell used as a drawing vessel. But the Sages state that if it was a pure pumpkin-shell used as a drawing vessel and it doesn’t have a need for this hoop, this hoop is not like the body of the pure pumpkin-shell used as a drawing vessel, and if the pure pumpkin-shell became defiled, the hoop did not become defiled.