Hypercolor was a line of clothing, mainly

T-shirt A T-shirt (also spelled tee shirt), or tee, is a style of fabric shirt named after the T shape of its body and sleeves. Traditionally, it has short sleeves and a round neckline, known as a ''crew neck'', which lacks a collar. T-shirts are general ...

s and

shorts Shorts are a garment worn over the pelvic area, circling the waist and splitting to cover the upper part of the legs, sometimes extending down to the knees but not covering the entire length of the leg. They are called "shorts" because they ...

, that changed

color Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are assoc ...

with heat. They were manufactured by Generra Sportswear Company of

Seattle Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest regio ...

and marketed in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

as Generra Hypercolor or Generra Hypergrafix and elsewhere as Global Hypercolor. They contained a

thermochromic Thermochromism is the property of substances to change color due to a change in temperature. A mood ring is an excellent example of this phenomenon, but thermochromism also has more practical uses, such as baby bottles which change to a differen ...

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. Generra Sportswear Co. had originally been founded as a men's sportswear

distributor A distributor is an enclosed rotating switch used in spark-ignition internal combustion engines that have mechanically timed ignition. The distributor's main function is to route high voltage current from the ignition coil to the spark plug ...

and importer in Seattle in 1980. The company was sold to

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

-based Farah Manufacturing Co. in 1984 and bought back by its founders in 1989. In 1986, the company added childrenswear and womenswear items to their portfolio. They struggled to meet the overwhelming demand for Hypercolor products. Between February and May 1991 they sold $50 million in Hypercolor garments. Generra went

bankrupt Bankruptcy is a legal process through which people or other entities who cannot repay debts to creditors may seek relief from some or all of their debts. In most jurisdictions, bankruptcy is imposed by a court order, often initiated by the debtor ...

due to mismanagement and fading demand in 1992. The Hypercolor business for the U.S. market was sold to The Seattle T-Shirt Company in 1993; Generra kept the rights for the international market. The company emerged from bankruptcy in 1995 as a licensing business. The Generra name was acquired by Public Clothing Co. of New York in 2002. Today, Generra Co. is a contemporary women's and men's apparel brand headquartered in New York City. In the early 2000s, the technique was revived by a number of apparel brands. In mid-2020, the color-changing clothing trend was revived yet again by several online retailers selling color-changing swim trunks.

Principle

Substances that can change color due to a change in temperature are called thermochromes. There are two common types of thermochromes: liquid crystals (used in

mood ring A mood ring is a finger ring that contains a thermochromic element, or "mood stone", that changes colors based on the temperature of the finger of the wearer. Finger temperature, as long as the ambient temperature is relatively constant, is si ...

s) and

leuco dye A leuco dye (from the Greek λευκός ''leukos'': white ) is a dye which can switch between two chemical forms; one of which is colorless. Reversible transformations can be caused by heat, light or pH; resulting in examples of thermochromism, ...

s (used in Hypercolor T-shirts). The color change of Hypercolor shirts is based on combination of two colors: the color of the dyed fabric, which remained constant, and the color of the thermochromic dye. Droplets of the thermochromic dye mixture are enclosed in transparent microcapsules, a few micrometers in diameter, bound to the fibers of the fabric. The thermochromic droplets are actually a mixture of several chemicals—

crystal violet lactone Crystal violet lactone (CVL) is a leuco dye, a lactone derivate of crystal violet 10B. In pure state it is a slightly yellowish crystalline powder, soluble in nonpolar or slightly polar organic solvents. The central carbon in the leuco form is ...

(the color-changing dye itself),

benzotriazole Benzotriazole (BTA) is a heterocyclic compound with the chemical formula C6H5N3. Its five-membered ring contains three consecutive nitrogen atoms. This bicyclic compound may be viewed as fused rings of the aromatic compounds benzene and triazole. ...

weak acid Acid strength is the tendency of an acid, symbolised by the chemical formula HA, to dissociate into a proton, H+, and an anion, A-. The dissociation of a strong acid in solution is effectively complete, except in its most concentrated solutions ...

), and a

quaternary ammonium salt In chemistry, quaternary ammonium cations, also known as quats, are positively charged polyatomic ions of the structure , R being an alkyl group or an aryl group. Unlike the ammonium ion () and the primary, secondary, or tertiary ammonium cation ...

of a

fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, ...

( myristylammonium oleate) dissolved in

1-dodecanol Dodecanol , or lauryl alcohol, is an organic compound produced industrially from palm kernel oil or coconut oil. It is a fatty alcohol. Sulfate esters of lauryl alcohol, especially sodium lauryl sulfate, are very widely used as surfactants. Sodium ...

as solvent. Together, these lead to a reversible chemical reaction in response to temperature change that produces a change of color. At low temperatures, the mixture is a solid. The weak acid forms a colored complex with the leuco dye by causing the

lactone Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure (), or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring. Lactones are formed by intramolecular esterification of the co ...

ring in the center of the dye molecule to open. At high temperatures, above 24–27 °C, the solvent melts and the ammonium salt dissociates, allowing it to react with the weak acid. This reaction increases the pH, which leads to closing of the lactone ring of the dye to convert it to its colorless (leuco) form. Therefore, at the low temperature the color of the shirt is the combination of the color of the encapsulated colored dye with the color of the dyed fabric, while at higher temperatures the capsules become colorless and the color of the fabric prevails.

References

External links

*{{cite web , url=http://electronics.howstuffworks.com/gadgets/other-gadgets/fabric-display2.htm , title=Thermochromic Fabric Displays , website=

HowStuffWorks HowStuffWorks is an American commercial infotainment website founded by professor and author Marshall Brain, to provide its target audience an insight into the way many things work. The site uses various media to explain complex concepts, termin ...

Clothing brands 1990s fashion Thermochromism Color of clothing