Much like Hoover or Jacuzzi, every time Post-it makes it into print it should have that little copyright symbol over its last letter. That it usually does not shows how the 3M sticky paper has become one of those rare brands that is now generic shorthand for an entire product category. The date 1968 refers to the year of the invention that would make Post-its possible even though the product, with the admirably plain and instructional name, only arrived on the market in 1980.

Chemist Dr Spenser Silver was attempting to create a superstrong glue when he accidentally created the exact opposite – a light, low-tack glue that could be used again and again and didn’t damage whatever it stuck to. He had invented a solution without a problem. In 1974 a colleague at 3M, Art Fry, inspired by the problem of finding a bookmark for his choir hymnal that wouldn’t keep falling out, had figured out a use for the glue. Using leftover canary yellow paper from a nearby laboratory the company trialled his idea in the US under the name “Press’n’Peel”. It wasn’t a success but Fry and Spenser were dogged in their determination that the idea could work. It wasn’t until 1980 that 3M released the handy blocks of yellow sticky-backed paper under the name Post-it. Fry has said that the notes, as a self-advertising product, spread “like a virus” – people seeing it on documents they received were instantly sold on it. It its first year alone, the Post-its racked up $2 million in sales.