Light Propagation
Velocity of light within a transparent medium varies according to its wavelength, causing different colours to refract at different angles. In the context of clear packaging films, refractive index dispersion affects how light interacts with the material and the product beneath it. This property determines the clarity and the level of chromatic aberration seen through a window.
Optical Property
Materials with high dispersion tend to split white light into its component colours more aggressively. This can cause a rainbow effect on the edges of printed graphics when viewed through a thick plastic layer. Refractive index dispersion is measured using an abbe refractometer at multiple wavelengths.
Control of this value is required for maintaining the visual appeal of luxury goods.
Coating Formulation
Adding specific minerals to a varnish can alter its refractive behaviour to enhance the brightness of the underlying print. Formulators balance the choice of resins to ensure that the refractive index dispersion does not obscure fine detail. If the dispersion is too high, the packaging may look hazy or distorted under retail lighting.
This effect is particularly important for high gloss coatings used in the cosmetics industry. Consistency in these optical values ensures that the brand colours remain accurate regardless of the viewing angle.
