Keilim 8:2-3

Keilim 8:2

If the beehive (as in the previous mishna) is unbroken and the sheretz (vermin) is inside it, the oven remains ritually clean; the same is true of a box and a waterskin. If the sheretz was in the oven, then any food in the beehive remains ritually clean. If the beehive, box or skin was punctured, then if it is used for food, the minimum size hole (that will allow the transmission of ritual impurity) is large enough for olives to fall through; if it’s used for liquids, the minimum size hole is large enough for liquids to seep into the vessel when empty. If the vessel is used for both food and liquids, we follow the more stringent standard, which in this case is large enough for liquids to seep into.

Keilim 8:3

Regarding a frameless screen that is placed over the mouth of an oven and recedes into it, if a sheretz was in it, the oven is rendered unclean; if the sheretz was in the oven, the food in the screen is rendered unclean. This is because only vessels can block the transmission of impurity in an earthenware vessel (and the screen doesn’t qualify because it has no frame). Regarding a jar of ritually clean liquid that was placed under the bottom of an oven, if there’s a sheretz in the oven, the jar and the liquids remain ritually clean. If the jar was inverted with its mouth in the oven’s airspace while there’s a sheretz in the oven, the liquid clinging to the sides of the jar (i.e., outside the oven’s airspace) remains ritually clean.