They were manufactured by Generra Sportswear Company of Seattle and marketed in the United States as Generra Hypercolor or Generra Hypergrafix and outside the US as Global Hypercolor. They contained a thermochromic (temperature sensitive) pigment made by Matsui Shikiso Chemical of Japan, that changed between two colors – one when cold, one when warm. The shirts were produced with several color change choices beginning in 1991. The effect could easily be permanently damaged, particularly when the clothing was washed in hotter than recommended water, ironed, bleached or tumble-dried.
Apart from being the staple attire in combination with LA Gear in the early 90’s a Global Hypercolour t-shirt was possibly THE most fun t-shirt you could own. Fact.
Between February and May 1991 the company producing them (Generra) sold $50 million in Hypercolor garments, but unfortunately went bankrupt due to mismanagement and fading demand in 1992.
Even though the fad has ‘faded’ we still think of Hypercolour fondly, so many sweat patches made cool.