Introduction Olive-boilers and dyers would both use large metal cauldrons for boiling. In order to prevent the water from spilling out they would put a plaster ledge around the sides of the cauldron. The question in our mishnah is: are these plaster ledges receptive to impurity? In other words, are they considered “vessels” which receive impurity or raw material which does not.
Menahem ben Signai testified concerning the ledge attached to an olive-boiler’s cauldron, that it is [liable to become] impure; and concerning that of dyers, that it is not [liable to become] impure, whereas they used to say the reverse. According to Menahem ben Signai, the ledge attached to the olive-boiler’s cauldron can become impure. This is because it is necessary for the proper use of the cauldron; it allows the olive-boiler to fill the entire cauldron with water. The ledge that the dyer uses cannot become impure because the dyer is careful not to fill the cauldron up to the top with water so that it might boil over. Previously people reasoned the opposite. Evidently they thought that the dyer’s made more use of the ledge than did the olive-boilers. The principle, however, remains the same. If the ledge is normally used to keep the water in, than it receives impurity. Unfortunately, I must admit, never having boiled olives or dye, that I cannot fully understand the reason why people would change their minds about which is a “vessel” and which is not.