Thermochromics Leuco Dye

Changes color with changes in temperature.
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SpotSee manufactures a range of Thermochromic products using Leuco Dye technologies. These are supplied in a variety of forms under their brand names Chromazone (reversible) and Kromagen (permanent).

We mix numerous Leuco Dyes with color developers and a series of fatty acids, esters, and alcohols that each have a defined melting point to provide a range of materials that respond to different temperatures producing a variety of colors.

These products change color over a temperature range specific to their formulation, providing a simple cost-effective method of monitoring temperature.

    Leuco Dyes change color with changes in temperature. Leuco Dyes are reversible, meaning they change color back and forth as the temperature fluctuates. It takes about a 5ºF (3ºC) temperature change for the Leuco Dyes to change color.

    Activation temperature points range from low refrigeration type temperatures through normal body temperatures to high temperatures that exceed the pain threshold.


    • Cold Activated Thermochromic Ink is used on labels and packaging to create a color change when cooled. (Clear to Color at 15ºC / 59ºF)
    • Touch Activated Thermochromic Ink will vanish when rubbed or touched to reveal an image or another color printed beneath. (Color to Clear at 31ºC / 88ºF)
    • High Temperature Thermochromic Ink is designed to change color just below the pain threshold alerting quality and process control users to a safety hazard – Too Hot! (Color to Clear at 47ºC / 117ºF)

    Temperature Range:

    • Chromazone: -10-69ºC/14-156ºF
    • Kromagen: 50-200ºC/122-392º

    Color Change

    • Chromazone – Blue, Black, Red, Orange, Green or Magenta to Clear upon heating
    • Chromazone – Clear to Blue, Black, Red, Orange, Green or Magenta upon cooling
    • Kromagen – White to Blue, Black, or Magenta upon heating to rated temperature


    • Quality Control
    • Process Control
    • Packaging
    • Labeling
    • Graphics
    • Advertising

    Leuco Dye Products are available in a wide variety of colors, temperatures and forms, which include powder, slurry, water and solvent-based ink, epoxy, and masterbatch.

    Leuco Dyes are more robust and less expensive than liquid crystals and can be used in a wider range of inks, plastics, etc. Because Leuco Dyes are not very sensitive, they do not make accurate thermometers but are used in applications where larger temperature differences are present or when temperature accuracy is less important. An Leuco Dyes life span is adversely affected by UV, extreme temperatures and contact with aggressive solvents.

    Applications are only limited by the imagination and include quality control, advertising and promotional applications, product labeling, toys, game pieces, and packaging. Leuco Dyes give life to materials and printing, offering the opportunity to engage and excite your audience with a graphic or component that changes color when stimulated by temperature. Great for manufacturing and process control where a visual indicator will reinforce temperature management.

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