Surface gloss measurement using a gonio-spectrophotometric method

This study compares gloss measurements for high-, medium-, and low-gloss samples using an angle-resolved gonio-spectrophotometer and a commercial glossmeter, demonstrating close agreement between the two instruments within stated measurement uncertainties. The gonio-spectrophotometer’s angular scanning capability enables a detailed investigation on how receptor aperture size and positioning influence gloss uncertainty. Using narrow aperture reflectance scans, we characterize the full reflectance distribution of each sample and quantify its impact on calculated gloss values. Results show that accurate estimation of aperture-related uncertainty requires resolving the angular profile of the specular peak, especially when the reflectance curve exhibits significant diffuse scattering. We present a practical procedure for determining gloss uncertainty from the measured reflectance distribution. This approach not only enhances the precision and reliability of gloss measurements across a wide range of gloss levels but also offers a framework that can inform the refinement of international gloss measurement standards.