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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…

A reference glossary for quality engineers, lab technicians, and sustainability professionals working with recycled pulp and recovered paper furnishes. For hands-on testing instruments that measure these contaminants, see the Pulmac MasterScreen™ and the full paper and pulp testing equipment range from Industrial Physics.  Stickies Tacky or adhesive contaminants in recycled pulp, originating from pressure-sensitive adhesives, hot melts, wax coatings, and latex…

A sticky is a contaminant found in recycled pulp that is tacky or adhesive at the temperatures and pressures encountered during paper or board manufacturing. Stickies originate from a wide range of sources in the recovered paper stream, including pressure-sensitive adhesives (PSAs), hot melts, wax coatings, latex binders, and synthetic polymers. Why stickies matter Stickies…

For any paper or board manufacturer relying on recycled fiber, contamination is a constant challenge. Stickies, shives, vessel cell elements, plastics, and hot melts can all cause serious problems at the machine - but only if they go undetected. Laboratory pulp screening is the method used to catch them before they do.  This guide covers how…