Online Acoustic Wave Sensing for Paperboard Score Quality Control
Inline acoustic wave sensing detects sub-surface paperboard delamination during scoring, stopping un-creased board defects before downstream cartoning line jams.
B-Value Measurement
Colorimetric Rating
Numerical quantification of the yellow and blue components within the CIELAB color space defines the tint of a paper surface. Practitioners rely on b-value measurement to assess the yellowness of bleached chemical pulp or the blueness of specialized printing grades. This value calculates the deviation from a neutral grey along a specific axis where positive figures indicate yellowing and negative figures signify a blue shift.
It stops applying once the substrate reaches total opacity or when the light source fails to provide the calibrated spectral power distribution required for industrial colorimetry. Calculations also exclude gloss effects to ensure the reading is isolated to the pigment and fiber properties of the sheet.
Instrumental Calibration
Spectrophotometers capture the reflectance data using standardized light sources like D65 to represent daylight conditions. The b-value measurement depends on the angle of observation and the exclusion or inclusion of ultraviolet energy from the light source. Fluorescent whitening agents significantly alter the results.
High concentrations of these chemicals push the metric into negative territory to meet market demands for high-brightness office papers.
Consistency Variance
Variations in wood species or cooking times during pulping change the residual lignin content. Because lignin absorbs light in the blue region, its presence increases the yellow tint. Mills adjust the chemical dosage in the bleach plant to stabilize the outcome.
Tight control prevents the visible mismatch of finished brochures when different paper batches are used in the same print run.