Composition and Chemical Paper Testing
The fiber composition of paper is determined with a light microscope (fiber micros¬copy). Due to the varying fiber morphology, both the fiber raw material and the pulping process can be determined. Chemical dyeing methods are used for con¬trast enhancement and quantitative determination of fiber composition (ZM IV/ 55/74; TAPPI T 401 om-93, Harders-Steinhäuser, Faseratlas).
The term moisture content refers to the amount of water in the paper in equilib¬rium with a defined ambient climate. It is determined gravimetrically in accor¬dance with ISO 287 (1985). A dry sample is produced by drying the paper to constant weight at 105 °C. The moisture content is expressed in percent, based on the moist sample.
Chemical testing is used to determine the components of paper. This is of sig¬nificance in papermaking for quality control and process control. Another im¬portant field of chemical paper testing is the control of papers for the packaging of food.