In 1968, chemist Spencer Silver, a researcher at 3M in Saint Paul, Minnesota, was trying to synthesize a super-strong adhesive for the aviation industry. The result was the exact opposite: a weak adhesive made of acrylic microspheres which, being spherical, touched the surface only in a few points. This reduced the contact area and therefore the adhesive strength, allowing materials to be easily attached and detached without leaving residues. At first, no one in the company could imagine a practical application for it, but Silver continued to believe in his discovery.
It took over ten years and the intuition of a colleague, Art Fry, for that “wrong glue” to transform into Post-itsdestined to become one of the most iconic and widespread office objects in the world. Even the iconic yellow color was not accidental: the researchers used the waste paper from an adjacent laboratory for the first tests.
The strange story of a sticker that shouldn’t have existed
Spencer Silverbachelor’s degree in chemistry from Arizona State University and doctorate from the University of Colorado, in 1968 was working on the development of new, increasingly resistant adhesives in the Central Research Labs of 3M – a leading multinational company in the sector of self-adhesive tapes and innovative materials. The goal was to obtain a very strong glue, suitable for industrial applications such as the construction of aircraft components. During the experiments, however, he obtained the opposite result to that sought: instead of a super glue, he discovered a low tack adhesive made up of acrylic copolymer microspheres. Unlike traditional glues, which form a continuous layer, these microspheres only touched the surface in a few places, reducing the contact area and therefore the adhesive strength. The result was a bond strong enough to temporarily hold two surfaces together, but weak enough to allow them to separate without leaving residues nor damage the materials.
At the time, however, no one in the company could imagine a practical application for an adhesive that didn’t stick permanently. Silver, however, was convinced that he had discovered something special and for years he tried to find a practical application for his invention, presenting it during internal seminars at 3M. Precisely because of his insistence, his colleagues began to call him “Mr. Persistent“until in 1972 he managed to obtain the patent on the microspheres.
The stroke of genius born in a church choir in 1974
The turning point arrived in 1974 thanks to Art Fry, a chemical engineer in 3M’s tape division, who had attended one of Silver’s seminars. Fry sang in the local church choir and he had a recurring problem: the paper bookmarks he used to keep track of the songbook kept falling off during services, forcing him to search through the pages to find the right hymn. During a Sunday service he was reminded of Silver’s “wrong” adhesive: if he had applied that glue to bookmarksthese would have stuck to the page while remaining detachable without ruining it. Back at work, Fry involved Silver and together they began to develop the product, immediately realizing that they had something much more important in their hands than a simple page marker. In fact, during development they started using those notes to leave messages in the officesensing that they could become a new communication tool.
The color canary yellow was born by chance: the reason
Even the characteristic canary yellow color of Post-its was born by chance. When developing the first samples, 3M researchers took some waste paper from an adjacent laboratory to do the tests: that card, the only one available at that moment, was yellow. The color remained by chance, but it turned out to be a good choice from a practical point of view, because the contrast between the bright yellow and the black ink makes the messages immediately visible, and, at the same time, distinguishes the piece of paper from any other document on the desk.
From uncertain launch to worldwide success
Despite the enthusiasm within 3M, bringing the product to market was not easy. In the 1977 the company launched it in four US cities under the name Press ‘n Peelbut i results were mixed. The problem was that the value of those sticky notes could only really be understood by using them.
For this reason, 3M changed strategy and organized a large free distribution campaign that went down in history as Boise Blitznamed after the city of Boise, where thousands of samples were distributed. The initiative proved to be a success: the 90% of people who tried the product said they would buy it. It was proof that those sheets sold themselves once they tried them.
Strengthened by that result, the April 6, 1980 3M launched the product throughout the United States with the definitive name of Post-it Notes. The success was very rapid: the sticky notes began to appear on documents that passed from hand to hand in offices, arousing the curiosity of new users and contributing to their diffusion. As Spencer Silver himself recalled, it was one of those products that no one thought they needed until it was invented.
Today Post-it notes are sold in excess 150 countries and their technology is the basis of thousands of different products. Yet the physical principle has remained identical to the one born almost by chance in Silver’s laboratory in 1968: a glue too weak to carry out the task for which it was designed, but perfect for revolutionizing another.
