Leviticus 6:28

But the earthen vessel. — The earthen vessels need by the Hebrews were unglazed. The ordinary domestic vessels throughout the East are so to this day. From their porous character, therefore, they would absorb some of the fat juices of the flesh which was boiled in them for the priests to eat. And as the absorbed juices could not be washed out, the inexpensive earthenware was to be broken up. (See Leviticus 11:33; Leviticus 11:35). During the second Temple the fragments were carefully buried in the ground when there was a large accumulation of them.

And if it be sodden in a brasen pot. — Being a solid metal, no juices could sink into it, and any of the most holy flesh that might adhere to it could easily be removed by washing. During the second Temple the scouring was done with hot water, and the rinsing with cold.