Cold foiling on shink sleeves is a logical alternative. Foil on labels creates a trendy metallic, high impact look. Special effects coatings add a textured surface you can feel. Matte areas or glitter ink provide contrast between a glossy shrink film surface and the bling of shiny foils.
Cold foil may be successfully printed on shrink film with a press fitted with chill rollers, UV lamps curing a cold foil adhesive formulated from a shrink ink vehicle, a hard cold foil nip system and lamination unwind and rewind to unspool the foil and wind up the waste foil.Most acrylic-based cold foil adhesives will crack if used on shrink film once the sleeve is shrunk on a container, so make sure the adhesive is suitable for shrinkability. K-Laser and UVitec offer such adhesives. And start printing with an anilox roll with both a high count and high bcm of about 500/5 bcm, and move to a 600/4 bcm once the setup is optimized.
All nip rolls are not equal – cold foil needs a nip roll with a hard durometer in order to print fine detail. To see if the nip roll is suitable, push against the nip roll with your finger – if the roll gives under pressure, it is not hard enough to print sharp detail. Use a cold foil nip roll with an 85 to 90 durometer hardness.
Some cold foils used for traditional surface printed labels may be used successfully with shrink films, especially transparent holographic foils. But remember that shrink film inks and cold foil adhesives are reverse-printed, that is, a mirror image with the image looking through the shrink film.
New foils are now available with clear primers that allow both colored foil and holographic foil to show through the film with maximum clarity.
Start with bright silver or gold foil designs, where press speeds of 500 feet per minute are common. Holographic cold foils create maximum sparkle and bling at speeds of 200-325 feet per minute. Limit their use to lower shrink areas of a container as the holographic embossing can shrink to an objectionable distortion. Use either bright silver or transparent holographic foils depending upon the design possibilities. Transparent holographic foils are forgiving, show no cracking, and can be printed over reverse-printed logos and text and under process colors for fantastic color sparkle effects.
To print foil in higher shrink areas, use patterns, such as diamonds or tapered lines, to allow foil to shrink without cracking.
Using Specialty Coatings and inks
Other special coatings available for surface printing on sleeves are glitter inks and matte, soft touch and UV casting coatings. In order for UV casting to work on shrink film, use a UV coating with high heat resistance like those used as a topcoat for direct thermal printers, as the cast holographic pattern will hold its pattern and not distort while the film shrinks underneath.
Shrink film surfaces are naturally glossy. Subtle surface design variations can be made by using special pattern printed UV matte coatings to create emphasis between color areas on the outside surface of shrink film. When an image appears to be in the foreground, the matte and holographic UV casting coating creates a more realistic background image.
Raised images use a specially-formulated UV coating that prints textures that can be felt on a shrink sleeve. Use tactile inks for embossed effects, as true embossing would disappear during the shrink process. Instead, turn the web and print with an extreme heavy flexo anilox roll from 25-90 bcm or use a rotary screen in order to create what looks like embossed areas or texture areas on a sleeve that create a texture customers can see, touch and feel.
These coatings must be formulated with shrink-capable ink components. The chemistry used in high viscosity UV coatings are formulated with special surfactants and modified urethanes that offer good flexibility, flow and good adhesion to various film substrates such as PET, PETG and PVC.
Cold foiling and printing special effects inks like tactile texture, mattes, soft touch and glitters on the surface of shrink sleeves bring a trendy metallic bling, and a highly stylized look on custom-shaped or conventional containers.
The look and feel of these shrink sleeved containers with effects coatings on the outside that customers can see and feel and sometimes smell, activate several of the senses. The package becomes a highly-designed container and a work of art with an attractiveness so compelling that many will buy the product just for the container – because there is nothing else like it.
About the authors: Tom Brough is Sales Manager, Cold Foils, for K-Laser USA (formerly AMAGIC Holographics, the company behind the book “Cold Foil for Dummies.” Tom can be reached by email at email@example.com. Andrew Wasserman is Vice President of UVitec. To inquire about UVitec’s tech sheet “Using Special Cold Foil Adhesives,” contact Andrew at firstname.lastname@example.org.