Gloss is a surface property responsible for luster and shininess of the sheet. The calendaring process in the paper production and finishing stage determine the overall glossiness of the sheet. Sheets with high gloss are said to be specular, while sheets with low gloss are diffuse. Gloss is determined by examining the ratio of reflected light to incident light. Paper gloss has an affect on the printability of the paper due to the its control over the amount of light that is reflected through the ink.
The TAPPI T 480 standard governs gloss measurement. Grain direction may have an affect on the gloss readings.