[keernan]

Not exactly what you are asking, but the thing that immediately jumped into my mind was: post-it notes. A 3M scientist, trying to improve adhesiveness, came across a property that caused stickiness with poor adhesiveness. Not exactly what he was tasked to invent.

Years passed. Until another 3M scientist, who was struggling with the bookmarks he put in the choir hymnals continuously falling out, thought about his colleague's odd sticky non-adhesive thingamajig. And voila! Post-its were born.