Considering the town’s many viscous specialties, people in Chicago are never far from the threat of spilling and staining their carpets: you could drip mustard (never ketchup) from a hot dog, spill a beer from Goose Island, or “accidentally” knock over a shot glass of Malört, the city’s iconically awful wormwood liquor. Factor in the roughly half a million residents who fall in the most spill-prone demographic—kids—and Chicago carpet-cleaning services have their work cut out for them. (So do Chicago upholstery-cleaning services, for that matter.) 

The carpet cleaners have a secret weapon on their side, though: Scotchgard. It makes spills easier to clean up, seemingly by magic.

Is Scotchgard Magic?

No, it’s just hard to see how it works with the naked eye. Think of it like this, though—if each thread in a carpet was a tree trunk in the rainforest, Scotchgard would be the dense canopy of leaves overhead, protecting everything below. Scotchgard’s barrier is an invisible one known as a surfactant. Surfactants lower the surface tension of liquids (causing them to break into beads rather than puddle), and adding fluorine to one can intensify the effect while also repelling oil and grease. Scotchgard’s fluorinated force field can rebuff nacho cheese, Malört, and everything in between for up to a year.

Where Did Scotchgard Come from, a Wizard?

No—Scotchgard is still not magic. It was invented by Patsy Sherman, a chemist at 3M and one of only a handful of female chemists employed by a major corporation in the 1950s. Appropriately, she discovered it the way most people spill stuff—by accident. One day, while Sherman was busy developing a new form of rubber, one of her lab assistants, Sam Smith, spilled a couple drops of synthetic latex on his shoes. Sherman and Smith realized that although the spill wouldn’t wash, it also wouldn’t absorb any new stains. 3M began selling the formula as Scotchgard in 1956, and Sherman’s ingenuity was rewarded with an induction into the Minnesota Inventors Hall of Fame (for the Non-Magical Only).