PET, PVC, BOPP film overview and 3D or rainbow effects from diffraction

If you’ve ever tilted a package and watched it flash like a soap bubble, you’ve seen diffraction at work. Those shifting rainbows come from micro-patterns pressed into a plastic film—often PET, BOPP, or PVC—that bend white light into its component colors. In this article, I’ll explain what each film is, how those “3D” or rainbow effects are made, and how to choose the right material for labels, packaging, and print projects. I’ll also touch on recyclability and safer finishing methods so you can make informed choices.

The films in plain English: PET, PVC, and BOPP

PET (polyester)

PET (biaxially oriented polyester, sometimes called BoPET) is a clear, strong, dimensionally stable film. It holds fine detail, accepts coatings, and tolerates heat better than many plastics. That stability makes PET a common base for holographic laminations, security foils, and label stocks that need crisp registration and clean die-cuts. Optical-grade PET can exceed 90% light transmission with low haze, which is helpful when you want the holographic pattern to appear sharp rather than muddy.

BOPP (polypropylene)

BOPP (biaxially oriented polypropylene) is lightweight, flexible, and very good at resisting water, oils, and many household chemicals. It’s widely used for product labels, flexible packaging, and roll-to-roll jobs where cost and throughput matter. The trade-offs: BOPP is less heat-tolerant than PET and can shrink or deform at lower temperatures. It’s tough and scuff-resistant, but if you need long service life in harsh conditions, PET or vinyl may outlast it.

PVC (vinyl)

PVC can be made rigid or flexible depending on plasticizers. Flexible PVC films are easy to convert and can conform to curves well. That said, PVC brings health and environmental concerns tied to vinyl chloride monomer, additives, and combustion byproducts. It remains common in signage and some decorative films, but many brands now prefer PET or BOPP when suitable.

Where the “3D rainbow” comes from

When white light hits a surface with microscopic grooves, different wavelengths scatter at different angles. That separation creates the rainbow you see—just like a diffraction grating in a lab. In packaging, manufacturers form those micro-grooves by embossing a pattern into a coating or into the plastic itself. There are two main approaches:

Embossed and metallized film
A master hologram (made from an interference pattern) is replicated onto a plastic film—commonly PET or BOPP—using heat and pressure. A thin aluminum layer is often added to boost reflectivity. The result is a bright, mirror-like rainbow with kinetic effects as you tilt the piece.
Cast & Cure (no foil transfer)
A UV-curable clear varnish is applied to the printed sheet. A reusable casting film carrying the micro-embossed pattern is nipped over the wet varnish and UV-cured through the film. The pattern is “frozen” into the coating. The film rewinds for reuse; no metal is left on the sheet. You still get that diffractive sparkle, but on a clear surface.

Both methods rely on the same physics: periodic features on the order of light’s wavelength that diffract, interfere, and split white light into spectral color. “3D” depth comes from complex patterns that steer light in multiple directions, creating motion and parallax as the viewing angle changes.

Printing on holographic film: getting colors right

Most label and packaging printers lay CMYK ink directly on holographic film. You can control where the rainbow shows through using a white underprint (also called a white underbase):

Flood white under the whole design yields solid brand colors with a uniform rainbow sheen beneath.
Spot white only under type, logos, or faces keeps those areas color-true while letting bare film shimmer in the background.
Tinted/partial white can soften or tune the holographic effect without killing it entirely.

If you’re designing, set up a dedicated “White” spot color layer for your printer and plan bleed and safe margins like any other label.

Choosing PET vs BOPP vs PVC for rainbow effects

Use PET when you need:

High heat resistance (e.g., hot-fill packaging, higher-temp converting)
Excellent dimensional stability for tight registration and fine lines
Optical clarity for sharp, high-contrast holographic patterns

Use BOPP when you need:

Cost-effective rolls for product labels
Good resistance to water, oils, and handling
Flexible web that runs fast on common packaging lines

Use PVC only when justified by the application:

Conformability on difficult curves
Existing print lines and adhesives optimized for PVC
Awareness of additive management and end-of-life risks

For transparent effects (window pouches, clear labels), choose clear holographic films or Cast & Cure so printed graphics remain legible and barcodes scan clean.

Durability and finishing

Lamination: Clear laminates (gloss or matte) protect inks on metallized holographic film. Matte over holographic yields a “pearl” look; gloss gives maximum sparkle.
Topcoats: UV varnish or protective coats help with abrasion and chemical resistance.
Adhesives: For labels, match the adhesive to the surface energy (glass vs HDPE), temperature, and expected moisture/oil exposure.
Cutting: Keep a clean vector cutline and at least 2 mm bleed; crisp PET stocks tend to die-cut cleanly, while softer films may need specific tooling.

Sustainability notes (practical, not perfect)

PET is resin code #1 and is widely recycled in bottle form. Labels and adhesives can contaminate rPET streams, so “design for recycling” matters. Clear, non-metallic finishes and wash-off adhesives help.
BOPP is resin code #5. It is technically recyclable, but curbside access for films is limited in many regions; store drop-off or specialized programs are more common.
PVC raises the most concern. Vinyl chloride is hazardous; flexible PVC can emit VOCs from plasticizers; and uncontrolled burning of PVC can generate dioxins. If an alternative film meets the spec, it often makes sense to use it.

If you want a lower-impact sparkle, Cast & Cure can add diffractive patterns via a UV-cured clear coating with a reusable casting film—no foil transfer left on the package. That can protect recyclability for paperboard and avoid metallized layers.

Quick spec cheat-sheet

Sharpest rainbow: Metallized PET holographic film
Budget labels, oily/wet products: BOPP holographic or BOPP + Cast & Cure
Heat tolerance: PET
Most curbside-friendly base (where infrastructure exists): PET bottles and some PET packaging; films are still tricky
Clear windows and legibility: Cast & Cure or clear holographic film with spot white underprint
Environmental caution: PVC (production, additives, and end-of-life fire risks)

Common questions

Is holographic film the same as a hologram sticker used for security?
Related, but not always the same. Security holograms often use mastered interference patterns and can include overt/covert features. Decorative rainbow films use similar diffraction, but not every film is a security device.

Will rainbow film distort my brand colors?
Only where you let it. Put white under important colors and type; leave the rest un-backed to shimmer.

Can I get the effect without metal?
Yes. Cast & Cure creates clear diffractive patterns by curing a UV varnish against a patterned film that’s reused.

Conclusion

PET, BOPP, and PVC each carry different strengths—PET for heat and stability, BOPP for cost and chemical resistance, PVC for flexibility with caveats. The rainbow “3D” look is simply diffraction from micro-embossed patterns, delivered either on metallized film or through clear Cast & Cure coatings. If you plan your white underprint, choose a film that matches the job and the recycling context, and think through finishing, you can get vivid shelf impact without nasty surprises on press—or at end of life.