Cold foil on BOPP labels — material selection and trial checks

Why is BOPP not a single construction?

Polypropylene label film comes in many grades: white or clear, with or without a coating, treated or untreated, printed on the face or the reverse. Two labels that are both called BOPP can behave differently under the same adhesive and foil, so the film grade and printing side belong in the project record from the start.

Cold-transfer suppliers say the same: API Foilmakers notes that substrate suitability for cold transfer should be confirmed by the customer. The same principle applies here.

• Film brand, grade and data sheet, including any topcoat.
• Which side is printed and which side is viewed.
• Any surface treatment and when and how it was measured.
• The adhesive and foil grades used in the same trial.

White film or clear film: which question changes?

On white film the foil usually sits on the printed face. On clear film the design may be viewed through the film, which changes layer order and what sits behind the foil. Decide the viewing direction before choosing a material system.

Surface-printed and reverse-printed constructions are different jobs. Reverse-printed clear labels also bring white backing, overprint and adhesive-clarity questions that do not arise on a white face.

Clear-film constructions and reverse printing are covered in the guide to cold foil para etiquetas transparentes.

Which materials need to be matched as a system?

Cold-transfer adhesive is a different material from the pressure-sensitive adhesive on the back of the label. Its grade, the foil, the film surface and the curing equipment need to suit each other, and the equipment and adhesive suppliers' documents set the operating requirements for your press.

• Adhesive supplier and grade, with the cure arrangement it specifies.
• Foil grade and lot.
• Ink, varnish or lamination placed over the foil.
• The anilox used to apply the adhesive, with its nominal specification and measured condition.

KURZ's FAQ states that for cold transfer, all components from the adhesive to the substrate to the transfer product should be matched. For adhesive and cure questions, see UV cold foil adhesive selection.

What should a BOPP trial roll record?

A trial is only useful later if the materials and conditions are written down. Use the project checklist below to record them, and compare changes one variable at a time.

For the wider UV flexo selection questions and sampling options, see the flexo cold foil materials page and the cold foil sample roll page.

How do you submit a BOPP project?

Send the film brand and grade, printed side, viewing direction, adhesive supplier and grade, press type, foil effect and the end use of the finished label. We reply about foil supply for the project; roll availability and terms are confirmed with you rather than assumed.

Review the options on the cold foil sample roll page, then send details through the request form or contact page.