What was the original intended purpose of the adhesive that eventually led to the creation of Post-it Notes?

Product innovation often comes from unexpected places! Some of the world's most successful products emerged from failures, accidents, or completely different research goals. The famous Post-it Note is a perfect example of this phenomenon, where an invention intended for one purpose found unexpected success in a completely different application. Do you know the real story behind this ubiquitous office staple?

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A super-strong adhesive for aerospace applications that failed by being too weak
A medical adhesive for surgical bandages that wouldn't damage skin when removed
A temporary glue for holding paper patterns to fabric during clothing manufacturing
A deliberate project to create repositionable notes for office workers