Why Does Laser Foil Produce Rainbow Effects?

When you see that angle-shifting, color-changing metallic brilliance on premium packaging — have you ever wondered how it's made? Is it printed color? A special coating? The answer lives in the microscopic structure of the foil itself.

Those rainbow color-shift effects come from a technology called Interference Lithography: microscopic diffraction gratings are pressed into the aluminum layer of the foil. These gratings have spacings of just a few hundred nanometers — roughly the wavelength of visible light. When light strikes them, different wavelengths are diffracted at different angles, creating the spectrum-shift effect.

Understanding this principle helps you choose the right pattern, set the right processing parameters, and cut through the confusion around the word "laser" in foil terminology.

How It's Made: Five-Layer Structure

① Base Film

PET Polyester (12–19 µm)

The structural backbone — provides mechanical strength and dimensional stability

② Release Layer

Proprietary Release Coating

Controls adhesion and separation timing during transfer — Lihyang's key R&D differentiator

③ Grating Layer

Holographic Emboss Layer

Micro-gratings pressed using an embossing master — determines pattern geometry and diffraction angles

④ Metal Layer

Vacuum-deposited Aluminum (~40 nm)

High reflectivity maximizes grating diffraction. Transparent laser foil substitutes AlOx for clarity

⑤ Adhesive Layer

Heat-activated (hot stamping) or UV-reactive (cold foil)

Determines bond strength to substrate — select based on stamping process

Request Laser Foil Sample Books

Physical sample books for C² Series and Laser Over-lamination Film — includes pattern swatches, specs, and processing guidelines

Request Samples Browse Patterns Online Digital Foiling Guide

Why Does Laser Foil Produce Rainbow Effects?