What was the original failed experiment that eventually led to the invention of Post-it Notes?

Product innovation often comes from unexpected places! Some of history's most successful commercial products emerged from failed experiments or happy accidents. The Post-it Note is one such legendary example in the world of office supplies and has a fascinating origin story that shows how serendipity can lead to revolutionary retail innovations. Test your knowledge about this iconic product's discovery and commercialization journey.

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An attempt to create super-strong adhesive for the aerospace industry
A test to develop waterproof paper for underwater navigation maps
Research to create heat-resistant labels for laboratory equipment
An experiment to develop invisible ink for secure government communications