cellio | daf bit: Bava Kama 100

Last week we talked about compensation for stolen animals where the animal changed state, such as a cow birthing a calf or a sheep being shorn for its wool. The mishna now moves on from theft to errors that affect the value of property.

A mishna on today's daf teaches: if one gave wool to a dyer to die and the dyer burned it in the cauldron, the dyer has to compensate the owner for his wool. What if he dyed it the wrong color? R' Meir says that, here too, the dyer must pay the owner the value of the wool. (The dyer buys the now-dyed wool, in other words.) R' Yehudah, however, says we compare the increase in value from the dyeing (even the wrong color is an increase over undyed wool) to the dyer's outlay (such as for materials). If the increase in value is greater than the outlay, the owner of the wool pays only the outlay. If outlay is greater than the increase in value, the owner pays only the increase in value. (100b)

According to R' Yehudah, in other words, if there was benefit the owner keeps his wool and still owes the dyer something, but since the dyer messed up he's only going to get the smaller of (a) his actual costs or (b) the increase in value.