Hypercolor was a line of clothing, mainly

T-shirt A T-shirt (also spelled tee shirt, or tee for short) 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-shir ...

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 ar ...

, that changed

color Color (or colour in English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is the visual perception based on the electromagnetic spectrum. Though co ...

with heat. They were manufactured by Generra Sportswear Company of

Seattle Seattle ( ) is the most populous city in the U.S. state of Washington and in the Pacific Northwest region of North America. With a population of 780,995 in 2024, it is the 18th-most populous city in the United States. The city is the cou ...

and marketed in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

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

thermochromic Thermochromism is the property of Chemical substance, substances to change color due to a change in temperature. A mood ring is an example of this property used in a consumer product although thermochromism also has more practical uses, such as b ...

pigment made by Matsui Shikiso Chemical of

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, 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,

bleach Bleach is the generic name for any chemical product that is used industrially or domestically to remove color from (i.e. to whiten) fabric or fiber (in a process called bleaching) or to disinfect after cleaning. It often refers specifically t ...

ed, or tumble-dried. Generra Sportswear Co. had originally been founded as a men's sportswear

distributor A distributor is an electric and mechanical device used in the ignition system of older spark-ignition engines. The distributor's main function is to route electricity from the ignition coil to each spark plug at the correct time. Design ...

and

importer An importer is the receiving country in an export from the sending country. Importation and exportation are the defining financial transactions of international trade. Import is part of the International Trade which involves buying and receivin ...

in Seattle in 1980. The company was sold to

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

-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 de ...

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 crystal Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals. For example, a liquid crystal can flow like a liquid, but its molecules may be oriented in a common direction as i ...

s (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 λευκό ''leuko'': 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 i ...

(the color-changing dye itself),

benzotriazole Benzotriazole (BTA) is a heterocyclic compound with the chemical formula . It can be viewed as the fusion of a benzene and triazole rings. It is a white solid, although impure samples can appear tan. It is used as a corrosion inhibitor for copper. ...

weak acid Acid strength is the tendency of an acid, symbolised by the chemical formula , to dissociate into a proton, , and an anion, . The dissociation or ionization of a strong acid in solution is effectively complete, except in its most concentrated s ...

), and a

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

of a

fatty acid In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...

(myristylammonium oleate) dissolved in 1-dodecanol 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. They are derived from the corresponding hydroxycarboxylic acids by esterification. They can be saturated or unsaturated. Lactones are formed by lactonization, the intramolecular esterification of the corresp ...

ring in the center of the dye molecule to open. At high temperatures, above , 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, term ...

Clothing brands 1990s fashion Thermochromism Color of clothing