What was the original 'failed' adhesive formula that eventually led to the invention of Post-it Notes initially designed to be?

Product design history is filled with accidental discoveries that revolutionized the marketplace. Some of the most ubiquitous products we use today were initially considered failures or were discovered through unintended circumstances. The story behind Post-it Notes represents one of the most famous examples of how persistence, cross-departmental collaboration, and recognizing potential in 'failed' experiments can lead to billion-dollar product lines. Test your knowledge about this iconic invention!

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A super-strong adhesive that would bond permanently to aircraft surfaces
A temporary adhesive specifically created for bulletin boards in offices
A medical adhesive for securing bandages without irritating skin
A heat-activated glue for binding paper documents together