משנה אויף במדבר 19:19

All are qualified to read the Megillah except a deaf person, an idiot and a minor. Rabbi Judah qualifies a minor. They do not read the Megillah, nor circumcise, nor go to the mikveh, nor sprinkling [purificatory waters], and similarly a woman keeping day for day should not take a ritual bath until the sun has risen. But if any of these things is done after dawn, it is valid.

Metal vessels, whether they are flat or form a receptacle, are susceptible to impurity. On being broken they become clean. If they were re-made into vessels they revert to their former impurity. Rabban Shimon ben Gamaliel says: this does not apply to every form of impurity but only to that contracted from a corpse.

If he dipped the hyssop during the day and he sprinkled during the day, it is valid. If he dipped it during the day and sprinkled at night, or dipped at night and sprinkled on the following day, it is invalid. But he himself may immerse at night and then sprinkle on the following day, for sprinkling is not allowed until the sun is risen. And if any of these was done as early as the rise of dawn it is valid.