"What is that white spray?" many fans wondered while watching the 2014 FIFA World Cup. Millions watched as referees used cans of aerosol foam to mark off 10 yards of space for free kicks, forcing defending players to stay behind the newly formed white line.
The spray disappeared from the turf within minutes, leading many to call it "vanishing spray."
Since its invention more than 20 years ago, the foaming serum is now ubiquitous across major soccer leagues. But how did vanishing spray come to be?