Dye Definitions — definitions of dyes, pigments and dyeing terms from Apparel Search
Thermochromic inks or dyes are temperature-sensitive compounds, developed in the 1970s, that temporarily change color with exposure to heat. They come in two forms, liquid crystals and leuco dyes; leuco dyes are easier to work with and allow a greater range of applications, including flat thermometers, battery testers, clothing, and the indicator on bottles of maple syrup that change color when the syrup is warm. The most well-known line of clothing utilizing thermochromics was Hypercolor.
Thermochromic inks or dyes are temperature sensitive compounds, developed in the 1970s, that temporarily change color with exposure to heat. They come in two forms, liquid crystals and leuco dyes. Leuco dyes are easier to work with and allow for a greater range of applications. These applications include: flat thermometers, battery testers, clothing, and the indicator on bottles of maple syrup that change color when the syrup is warm. The most well-known line of clothing utilizing thermochromics was Hypercolor. The thermometers are often used on the exterior of aquariums, or to obtain a body temperature via the forehead. Coors light uses thermochromic ink on its cans now, changing from white to blue to indicate the can is cold.
| The above article is licensed under the GNU Free Documentation License. From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/thermochromis). Article modified by Apparel Search 9/26/11 |
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How the Two Systems Change ColorLiquid-crystal thermochromics work by structure: as temperature changes, the spacing of the crystal layers changes, and with it the wavelength of light they reflect, sweeping through a spectrum in sequence. That ordered response is why liquid crystals serve in forehead and aquarium thermometers, where the color must mean a specific temperature. Leuco dyes work by chemistry: a dye held in a microcapsule with a solvent is colored while the solvent is solid and loses its color when the solvent melts at the design temperature, or the reverse. Encapsulation lets leuco dyes be printed like ordinary inks and pigments onto shirts, mugs, labels and cans — one transition temperature, one color flip, engineered anywhere from freezer cold to hot-drink heat. Thermochromics in ClothingHypercolor shirts of the late 1980s and early 1990s made the effect a fashion event: body heat from a hand or an armpit visibly changed the garment's color. The same sensitivity set the limits — the microcapsules degraded with harsh washing, heat and ultraviolet light, so the change weakened over the garment's life. Modern applications are more targeted: safety and promotional garments, children's products that signal bath or drink temperature, and novelty prints where a hidden design appears in warmth. In specification terms a thermochromic print must name its activation temperature, its two color states, and its wash limits, because unlike a normal pigment it is a working mechanism printed onto cloth, not just a color. Common QuestionsWhat are the two forms of thermochromic color?Liquid crystals and leuco dyes. Liquid crystals are used in precision applications, because their responses can be engineered to react at specific temperatures. Leuco dyes are easier to work with and allow a greater range of applications, though their color change is less precise. What is thermochromism?Thermochromism is the ability of a substance to change color due to a change in temperature. It is one of several types of chromism. A mood ring is an excellent example, and the effect is also used in baby bottles that change color when cool enough to drink and in kettles. Which clothing made thermochromics famous?Hypercolor, the line of clothing that changed color with body heat and sunlight warmth, was the most well-known clothing application of thermochromic dyes. Coors Light cans use the same principle in reverse, thermochromic ink changing from white to blue to show the can is cold. More to ExploreMore from Apparel Search: Dye Definitions | Clothing Industry Glossary | Fashion Terms | Apparel Search Home
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