Virgin SBS against White Lined Chipboard for Retail Facings
Virgin SBS provides superior print brightness, stiffness consistency, and crack-free scoring, whereas recycled board lowers initial cost but adds waste.
Fluorescence Whitening Agents
Optical Adjustment
Synthetic compounds absorb invisible ultraviolet radiation and re-emit the energy as visible blue light to counteract the natural yellowish tint of wood pulp fibres. Fluorescence whitening agents integrate into the papermaking process to modify the spectral reflectance curve of the final substrate. These additives function by bridging the gap between reflected wavelengths and the perception of high-brightness whiteness in uncoated or coated papers.
The chemical action remains active only while the substrate receives exposure to an ultraviolet source, which dictates the appearance of the sheet under standard daylight conditions compared to artificial tungsten lighting.
Spectral Control
Manufacturers apply these molecules during the wet end stage of production or within surface sizing formulations to achieve specific brightness targets requested by converters. High concentrations of the agent increase the intensity of the blue emission, shifting the shade of the paper toward a cooler or more bluish-white appearance. Printers must account for the presence of these additives because the emission level changes the colorimetric profile of the stock during the reproduction of specific gamut ranges.
Precision in the dosing process prevents metamerism, a condition where the substrate shifts in appearance when viewed under different light sources that provide varying intensities of ultraviolet content.
Technical Boundary
Excessive accumulation of these agents leads to saturation, a point where further additions yield no gain in brightness and may introduce a greenish or dull grey cast to the sheet. Quality control protocols verify the performance of the additives through spectrophotometric analysis conducted under D65 illuminant conditions to measure the deviation from standardized neutral white points. Each formulation requires stable pH levels within the machine water circuit to maintain the solubility of the molecules and ensure uniform distribution across the web.
Uniformity of the emission remains a critical factor for the visual consistency of packaging materials that require high contrast for detailed graphic output.