Glow-in-the-Dark
(Phosphorescence)

Ink

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Adding fun and mystery to Halloween, snack foods, beverages, and other consumer packaged goods (CPG) campaigns, this printed ink glows green after being exposed to blacklight or UVA light. The heavier the ink coat weight, and the longer and stronger the charging, the brighter and longer-lasting glow. Glow in the dark packaging has become popular amongst major candy and chip brands to help stand out against their competitors. 

in-the-light

in-the-dark

Design tips:

Use large 100% areas for Glow-in-The-Dark ink and place this ink against a white (or even shiny metal) background for best contrast and glow reflectance. Remember that your eyes will need to adjust to the dark, too, for the best perception of glow. Contact CTI for more design tips and best practices for commercial printing, especially solvent-based gravure.

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Phosphorescence versus Fluorescence –
what’s the difference?

While these may seem the same, they’re actually very different technologies. Phosphorescence occurs when a material absorbs energy, then emits it over time. Applications of phosphorescent inks on CPG packages typically are called glow-in-the-dark. 

 

The intensity and duration of the glow depend on the amount of ink coverage and the intensity and length of time charged in sunlight or UVA light containing 365-nanometer wavelengths such as blacklight. More intense light will charge the pigment faster; less intense light will take longer to achieve a strong glow-in-the-dark effect. For reference, full daylight, depending on clear or cloudy skies, can be about 10,000-50,000 lux. Normal offices are around 500 lux, whereas grocery and retail stores may be around 750 lux. In sunlight, the maximum charge would be achieved in five minutes. Under indoor fluorescent light at 500 lux, it would max out in 10 minutes.

in-the-light

in-the-dark

Fluorescence, in contrast, occurs when material gets excited with a specific wavelength of light – coincidentally 365 nanometers – and then emits a different wavelength, which determines its fluorescing color, such as green, yellow, red, blue, etc. This allows the printed ink to be virtually invisible until a UV light causes the ink to fluoresce and turn a bright color. That’s why fluorescing inks make great security and authentication features, as well as for batch traceability. 

Ironically, phosphorescent glow-in-the-dark inks also fluoresce.
 

natural light

UV light

To round out the parade of definitions and clarify even more, there are also fluorescent color inks, also called day glow or neon inks, which also include pigments that UV light excites and that can be seen fluorescing in daylight, which makes them more visible for safety and other graphic design effects. However, these are typically used for enhancing the base color – so the fluorescent orange is an even brighter orange than normal. CTI does not supply fluorescent inks, only invisible to color under UVA light fluorescing security inks. 
 

Night Sky

Advantages:

  • Printable technology, just like other high speed commercial inks

  • Full control over brand identity, graphic design, and placement, either through existing printed label or direct package/container printing

  • Excellent laydown, print quality, bonds strengths and mileage

  • Many high-speed commercial printing formats available

  • Long-term chemical stability

  • Safe for indirect food contact

  • BPA-, BPF-, BPS-free and compliant with REACH, Prop 65, CONEG, and many other regulations. PVC (phthalate-free) formula available for Textile screen inks.

Glow Properties

For best glow, apply the heaviest coat weight possible –

contact CTI for Flexo anilox and Gravure cylinder recommendations. Pigment reaches maximum energy absorption under 365-nanometer wavelength light. Charge in sunlight for five minutes or under strong fluorescent lighting for 10 minutes. Glow-in-the-dark strength and duration depend on the combination of printed film weight, charging light intensity and time length.

 

Glow in the DArk Industries and Applications

Beverages and Foods  

Canned, bottled and fountain-served beverages; snacks in flexible glow-in-the-dark packaging; cereal boxes; secondary packaging.

Clothing  Sports apparel

 

Availability

Textile Screen, Water-based Screen, UV Screen, UV Flexo, Metal Deco, Water-based Flexo, Water-based Gravure, Solvent-Based Flexo, Solvent-Based Gravure, Wet Offset, UV Wet Offset, UV Dry Offset. Other formats may be available.