It all began in the period between 1964 and 1966: Spencer Silver, a chemist working for 3M (Minnesota Mining and Manufacturing Company), accidentally invented a sticky adhesive, a new adhesive acrylic polymer (which would be given patent #3.691.140 in 1972). This “glue” had a low adhesive power which was nevertheless sufficient to enable a sheet of paper to be stuck to a surface and unstuck as often as desired, without leaving a mark. Curiously, he discovered it by accident while researching very strong adhesives. He circulated the information among his colleagues in the laboratories, including a certain Art Fry and sought to sell his invention in the form of a spray (as it is currently sold to be used in the graphic arts). Due to lack of success, the adhesive polymers program was shelved until 1972.
Then came 1974, the year that would see the birth of the small canary yellow sheet of paper that can be stuck anywhere. Like every Sunday, Art Fry, a researcher at 3M, was singing in the choir of St. Paul's church in Minnesota. He used small pieces of paper to mark the day's hymns in his hymn book. Fed up with his bookmarks constantly falling out, he suddenly remembered a substance invented by one of his work colleagues, Spencer Silver, a glue with low adhesive power. He then had the idea of putting a little of the glue onto a piece of paper. It worked! He could now move his bookmarks from one page to the next without them falling out. He had just invented the "post-it".
Developing a quality product required many years of work in the 3M laboratories and plants. It would then take Art Fry another year and a half to develop the final product, as its manufacture required high precision calculations. The paper needs to be treated several times and the adhesive layer must be sufficiently thin in order to avoid the part with glue being thicker than the paper.
The "post-it" was first sold in the United States in 1980, then in Canada, and finally in Europe in the following year. The Post-it was designed to be used to write messages and stick them on any type of surface without causing any damage. The small 7cm by 7cm canary yellow square of paper is now available in eight different sizes, 25 shapes and 62 bright and it is sold in 150 countries.
The "Post-it" is now part of everyday life and phone alerts or other electronic notepads have not succeeded in dethroning the king of the organization and the "to-do list".