Standardized Laboratory Methods for Evaluating Matte Print Coating Burnishing
Standard laboratory burnish evaluation uses controlled sled friction and 60-degree delta gloss measurements to quantify matte coating asperity degradation.
Specular Glossmetry
Gloss Measurement
Optical evaluation methods in this category measure the light reflecting capability of a paperboard or cured ink surface under standardized geometric conditions. The specular glossmetry determines the gloss level by comparing the amount of reflected light to that from a polished black glass standard. This measurement is important for verifying the consistency of high gloss coatings and matte finishes.
Reflectance Angle
Execution involves directing a light beam at a specified angle onto the specimen and measuring the intensity of the reflected light. Common angles are seventy five degrees for paperboard, sixty degrees for typical print films, and twenty degrees for very high gloss surfaces. This test requires a perfectly flat specimen to prevent light scattering and ensure accurate measurements.
The instrument must be calibrated before each test run using a standard tile of known reflectance to maintain accuracy across different production batches.
Surface Uniformity
Maintaining consistent gloss levels across the sheet ensures a uniform appearance and prevents visual defects in the finished package. This method does not apply to highly textured or corrugated boards where the surface is not flat enough to reflect light uniformly. Gloss variation can indicate uneven coating application or inconsistent ink drying during the printing process.
Regular testing helps to identify and correct these issues early in the production run.