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Key terms Term  Definition  Gloss  The degree to which a surface reflects light in the specular (mirror) direction. Higher gloss means a shinier surface.  Specular reflection  Light reflected at the equal and opposite angle to the incident light, as from a mirror.  75 degree geometry  The measurement angle used for paper and board gloss, taken…

Gloss is the visual perception of shininess, and it comes from the way a surface reflects light. When light hits a very smooth surface, most of it reflects in a single direction, the specular direction, and the surface looks glossy. When the surface is rough or open, light scatters in many directions and the surface…

Gloss is a measure of how much light a paper or board surface reflects in the specular, or mirror, direction. A high-gloss sheet reflects light sharply and looks shiny. A matte sheet scatters light and looks dull. In the paper and board industry, gloss is a controlled optical property because it shapes how printed packaging,…

Thickness, also called caliper, is the perpendicular distance between the two principal surfaces of a sheet of paper or board, measured under a defined static load between hard metal platens. It's one of the most fundamental physical properties in paper and board manufacturing, and it directly influences strength, stiffness, bulk, and how a material runs…

Thickness, or caliper, is one of the first properties many mills measure, and one of the most revealing. It tells you how much material is in a sheet, and it points to how that sheet will behave under stress, through a press, and inside a finished package. Getting it right is a balancing act between…

Key terms Caliper: Another word for thickness; the perpendicular distance between the two principal surfaces of a sheet, measured under load.  Single sheet thickness: The thickness of one sheet of paper or board, measured under a defined static load.  Bulking thickness: The thickness of a single sheet, calculated from a pack of superimposed sheets measured…

What is clay and mineral pigment testing for paper and board? Clay and mineral pigment testing measures the brightness and color of the mineral pigments used as fillers and coating pigments in paper and board, such as kaolin clay, calcium carbonate, talc, and titanium dioxide. Because the optical properties of these pigments directly affect the brightness, whiteness,…

Mineral pigments, including kaolin clay, calcium carbonate, talc, and titanium dioxide, are used as fillers and coating pigments throughout paper and board production. They influence the brightness, whiteness, opacity, and color of the finished sheet. For quality and R&D experts, measuring the optical properties of these pigments is an important quality control step. But mineral…

Clay and mineral pigment testing Key terms Mineral pigment (filler): A finely ground mineral added to paper and board to improve optical properties, printability, and to manage cost. Common examples include kaolin clay, calcium carbonate, talc, and titanium dioxide.  Brightness: The reflectance of a sample measured under defined conditions. For mineral pigments it is reported on the…