Wavelength Measurement
Percentage of light reflected from a printed or unprinted surface at individual wavelengths across the visible spectrum. In the printing and paperboard industries, spectral reflection provides the raw data needed to calculate precise colour coordinates, such as Lab values, under different lighting conditions. This physical measurement is essential for matching brand colours and maintaining print consistency across different production runs.
Surface Property
Roughness, porosity, and the presence of optical brightening agents in the paperboard influence the way light reflects off the surface. A glossier and smoother board yields a higher specular reflection, which makes the printed colors appear more saturated and vibrant. Conversely, a rough board scatters the light in multiple directions, which reduces the intensity of the reflected light and changes the perceived color.
When formulating inks, technicians adjust the pigment concentration to compensate for these substrate characteristics and ensure that the final spectral reflection matches the digital reference.
Industrial Evaluation
Spectrophotometers measure this reflection at intervals of ten or twenty nanometers across the visible spectrum to generate a unique curve for each color. This curve acts as a fingerprint that is independent of the observer and the light source, which allows for objective quality control. Accurate color measurement reduces waste by catching drift before it becomes visible to the eye.
