When changing a child’s diaper on shabbos, the adhesive tab of the diaper might become attached to the child’s clothing. Is it a problem of borer to remove the attached diaper (the bad) from the clothing (the good)?
It isn’t borer because they are two separate items that are touching each other, and that is not considered a mixture, as it is clear that the two things are separate. This is the case with many korayah cases, such as separating tabs, pulling off the plastic seal on top of a container, etc. and it isn’t borer, in this instance it surely isn’t.