The standard ISO 8254-3-2016 Measurement of paper and Cardboard gloss Part 3: TAPPI method for 20 ° gloss with converging beam of light specifies a method for the measurement of paper and Cardboard gloss at 20 ° incident angle using the converging beam of light method. Gloss is the ability of a paper surface to reflect light, affecting its visual effect and printing performance. The standard uses the TAPPI method to ensure the accuracy and conformity of measurement results through specified instrumentation and operating procedures. The standard details sample preparation, measurement procedures, instrumentation requirements and environmental conditions. It is suitable for the production, quality control and research of paper and Cardboard, especially for the detection of low gloss materials, and has important application value.