Comentário sobre Kelim 3:5

כלי חרס הבריא – that is not shattered or broken.

One who lines a sound vessel: Rabbi Meir and Rabbi Shimon say: [the lining] contracts impurity.
But the sages say: a lining over a sound vessel is not susceptible to impurity, and only one over a cracked vessel is susceptible.
And the same dispute applies to the hoop of a pumpkin shell.
Section one: The debate in this mishnah concerns a person who lined the outside of a vessel that was in sound shape. According to the Tosefta, he did this so that he could cook with this vessel.
Rabbi Meir and Rabbi Shimon rule that if the vessel becomes defiled from the inside (earthenware vessels can only be defiled from the inside), the lining on the outside is also impure. The lining can then subsequently defile any food or drink that touches it on the outside.
The other sages say that the lining is susceptible to impurity only if it is necessary to hold the vessel together. So the lining of a sound vessel is not susceptible, whereas the lining of a cracked vessel is.
Section two: Dried pumpkin shells were used to draw water. They would attach a hoop to the shell in order to strengthen it. This is similar to the previous case, in that both are cases of strengthening a vessel that is in sound shape. According to Rabbi Meir and Rabbi Shimon the hoop is susceptible to impurity, whereas the sages hold that it is not.

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.