A crack in a sealed oven is exactly the circumference of a plow-rod (one handbreadth around). Is the oven impure?
Halacha 4: An oven crack with a circumference equal to the opening of a plow-rod (one handbreadth around) makes the oven impure — even if the plow-rod cannot physically be inserted, the measure alone determines the ruling.
Question 2
A person intentionally makes a tiny pinhole in a sealed jug. Does this disqualify the seal?
Halacha 6: The minimum-size rules for holes only apply to naturally-formed perforations. For holes made by human hands, even the smallest hole disqualifies the seal — no minimum size applies.
Question 3
Can tin be used to seal a container for protection from corpse-tent impurity?
Halacha 8: Tin and lead are explicitly invalid sealing materials — 'because they are pliable without adhesion (patil v'ein tzamid).' The seal must be an adherent closure, not just a physical barrier.
Question 4
A jug is wrapped in fish-skin paper and sealed at the bottom. Does it protect its contents?
Halacha 11: A jug wrapped in fish-skin or paper and tied closed from below protects its contents. Without the tying from below, even smearing clay on the sides is insufficient.
Question 5
An earthenware tube is placed in a sealed jug so that one end is inside the jug and the other end opens into a corpse-tent. What is the status of the jug and its liquid?
Halacha 8: The jug and its liquid remain pure (the tube is at the side and the seal is maintained for the jug's contents). The tube itself is impure because its far end is open to the corpse-tent — an exposed opening, even if curved, is not considered closed.