Another process to finish a lenticular piece with a back side print is to laminate a printed paper backer to the lens.
First the lenticular portion is printed and opaque white is applied. This is not only to achieve opacity but also to hide the adhesive used to adhere the paper to the lens. The backside print is on the paper stock. Text to cover weights are commonly used. Typically the paper backer is printed and sent to the laminator along with the
printed lens for the laminating process.
A big advantage of paper laminate is great opacity that will allow for almost any high density, color-intensive backside graphics.
Paper laminate is less costly than a poly barrier film laminate.
Unfortunately curling can be an issue. It is advisable to run the grain of the paper perpendicular to the direction of the lens. Use the minimum amount of roller or nip pressure possible. An adhesive with a low moisture content should be used.
Paper has a tendency of fraying or pealing at the corners with use over time.
The paper laminate could add substantial weight. If your piece is a mailer this may effect the postage and/or shipping costs.
Barrier Film Laminate.
There are two types of barrier film laminate: thermographic and pressure sensitive.
They both have choices in opacity, from whatever the manufacturer offers up to 100%.
The thermographic barrier film adhesive is activated by heat during the laminating process. The laminating machine has a controlled heating device that warms the barrier film just as it is being married to the lens.
Thermo Barrier film laminate has great adhesion and has a choice of finishes like matte or gloss. It has very good color display when printed. It is thin and very light weight, less costly
than pressure-sensitive film and even some paper laminates.
Due to heating and amount of pressure needed on the laminating machine’s rollers, there may be a degree of curling. There are some new products on the market called “low melt” or “ low heat”, meaning that they have been designed to activate their adhesive at a much lower temperature. Just as with the paper laminate, roller pressure or nip is a factor. The least amount of pressure or nip required while still ensuring a good bond will help keep any amount of curl to a minimum.
Pressure Sensitive Barrier Film
Pressure Sensitive barrier film has a wet adhesive with a liner. When the liner is removed, the adhesive is exposed and the barrier film is married to the lens via pressure. Once again, the amount of roller or nip pressure is important to prevent curling. However, because heat is not used and the adhesive has a very high tack the roller or nip pressure can be very light.
Pressure Sensitive Barrier Film is less likely to cause curling. It has great opacity and great adhesion and is available in a choice of finishes like matte and gloss. It’s thin and very light weight and has good color display when printed.
Unfortunately Pressure Sensitive Barrier Film is expensive. When compared to thermographic barrier film, it can approach double the cost.
Printing on Barrier Film
Typically the lens will have the poly barrier film applied and then the sheets
are ready for printing on the back side or barrier film side.
Dyne is the amount surface energy in your substrate and ink. The Dyne level is a very important factor to good ink adhesion to the barrier film. As a general rule the dyne of the substrate should be higher than the dyne of the ink.
Target Dyne levels:
Corona treated polyester – range up to 72 dynes/cm
Adhesion treated polyester – range 42 – 46 dynes/cm
Untreated polyester – range 40 – 44 dynes/cm
Due to the multitude of finishing options, choosing the finish that best suits your projects needs may be overwhelming. For more information, consult your printer or "ask Lenny" and we'll see if we can help you find the answer.