The central compound of Silver’s adhesive was an acrylate copolymer. But the
adhesive was too weak and wouldn’t stick for long. Acrylate polymers were a
category of chemical compounds often used in paints, plastics and textiles.What
Fry wanted was the perfect pressure-sensitive adhesive. He experimented with
particles called microspheres, tiny round molecules. When sprayed onto a surface,
the adhesive coating was just like the pebbled surface of a basketball. By spraying
the adhesive in the form of these round microspheres, he could coat a surface that wasn’t too sticky or too weak. This allowed a Post-it note to stick onto the page of
a book, but it could later be easily removed and stuck again somewhere else.
Conversely, normal packing tape had a flat surface, hence allowing it to stick
permanently.