Angels share

A term to describe an amount of something lost during a process or processing and cannot be retrieved or returned

It was originally coined by the Japanese. During the sake making process to describe when a small amount would evaporate. As they said that portion went to the angels.

This term can used in other situations to describe a loss (of a portion) that cannot be gotten back.

Guy1: What happened to all the sake' we made?
Senior: proably a bit of it evaporated ... we used to call that the angels share. We often imagined they were up there drinking it right now.