Leuco dyes transition from a specific color to clear (colorless) when they reach their activation temperature. This change is reversible — the color returns as the temperature drops back down. A temperature change of approximately 5°F (3°C) is all that is needed to trigger the transition. 

Both are thermochromic technologies, but they differ in key ways: 

• Leuco Dyes transition between one color and clear, are easier to incorporate into standard manufacturing processes, less temperature-precise, and more common in packaging, toys, and labels. 

• Liquid Crystals transition through a spectrum of visible colors (e.g., Black » Red » Green » Blue), are highly temperature-precise, require more specialized manufacturing, and are more common in precision gauges and thermometers. 

Standard leuco dye products are available for temperatures ranging from -10°C to 69°C (14°F to 156°F), with specific products covering: 

• Cold activation: Clear to Color at 15°C / 59°F 

• Touch/body-heat activation: Color to Clear at 31°C / 88°F 

• High-temperature / safety indication: Color to Clear at 47°C / 117°F 

Colors and activation temperatures can be customized. 

Common applications include: 

• Packaging (food and beverage labels, temperature indicators) 

• Promotional and novelty items (mugs, toys, apparel) 

• Food safety indicators 

• Security printing 

• Industrial process monitoring and quality control 

• Labels and graphics 

Thermochromic Leuco Dye products are available in the following formats: 

• Powder (free-flowing pigment) 

• Slurry (liquid suspension) 

• Masterbatch (pellets for plastic injection molding or extrusion) 

• Concentrate (e.g., Kromagen Concentrate) 

• Inks and coatings (formulated for specific printing methods) 

• Liquid crystal screen inks 

A Masterbatch is a solid or liquid additive used to color or add properties to plastics. Thermochromic masterbatch contains Leuco Dye pigments in a carrier resin and is designed for use in plastic injection molding or extrusion processes — allowing manufacturers to produce plastic items that visibly change color with temperature. 

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Yes. Both the color and the activation temperature can be customized to suit your specific application and printing or manufacturing capability. Contact your supplier to discuss custom formulations. 

Compatibility levels for Chromazone Powder: 

• Fully Compatible: Toluene, Water, Xylene, Isobutanol, Mineral Spirits, White Spirits, High Chain Alcohols, Silicones 

• Compatible at less than 5% volume: Isopropanol, PMA, Ethyl Acetate, Glycols, High Chain Ketones, DMF, High Chain Acetates, Naphtha, Banana Oil, Butanone Oxime 

• Not Compatible: Acetone, MEK, Butyl Acetate, Methyl Pyrrolidone, Ethanol, Dichloromethane 

• Limited Short-Term Stability: Butanediol, Propyl Acetate 

Compatibility levels for Chromazone Slurry: 

• Fully Compatible: Toluene, Water, Xylene, Isobutanol, High Chain Alcohols, Silicones 

• Compatible if diluted 50/50 with water and less than 10% overall volume: Isopropanol 

• Not Compatible: Acetone, Dichloromethane, PMA, MEK, Ethyl Acetate, Ethanol, Glycols, Methyl Pyrrolidone, Ammonia, Monoethanol Amine 

Compatibility levels for Kromagen Concentrate: 

• Fully Compatible: Water, Ammonia 

• Compatible if diluted 50/50 with water and less than 10% overall volume: Isopropanol 

• Not Compatible: Acetone, PMA, MEK, Ethyl Acetate, Isobutanol, Ethanol, Methyl Pyrrolidone 

Yes. All Chromazone components have been either registered or pre-registered under REACH. Chromazone products do not contain any chemicals listed on the SVHC (Substances of Very High Concern) list (as per the 19th December 2015 update). 

Standard Chromazone formulations comply with: 

• EINECS (European) 

• TSCA (USA) 

• DSL/NDSL (Canada) 

Note: Compliance with Korean KECL or Australian AICS may vary by formulation — contact your supplier to confirm. 

Yes. Chromazone products comply with both RoHS and WEEE directives. Test certificates can be provided on request. 

Chromazone pigments have been independently tested against DIN EN 71-3:2014-12 (Safety of Toys — Migration of certain elements) and do not contain listed heavy metals in excess of EN 71 set limits. Note that the final end product may still require independent testing for full compliance. 

This depends on the type of contact: 

• Direct Food Contact: Chromazone products are NOT suitable for direct food contact applications unless the specific formulation has been validated and approved by an accredited certification body. 

• Indirect Food Contact (non-food-contact surface of packaging): BPA-free Chromazone products are suitable. BPA-containing products are NOT suitable unless approved by a certification body. 

Chromazone is available in both BPA-containing and BPA-free formulations. Products sold as ‘Bisphenol A free’ do not have any BPA intentionally added. Always confirm the correct formulation with your supplier before ordering. 

Chromazone powder contains low levels of formaldehyde. There is a Specific Migration Limit (SML) of 15 mg/kg. For plastic masterbatch applications, experience has shown formaldehyde is generally not an issue, but the finished product manufacturer is responsible for confirming the final article meets SML requirements. 

Yes. Chromazone products are manufactured under BS EN ISO 9001:2008, meeting Good Manufacturing Practices for the production of packaging inks for indirect food contact surfaces. Chromazone also complies with EUPIA / CEPE guidelines for pigment production.