Pulp and paper testers include specialized sensors, instruments, COBB testers, and test equipment for evaluating the material properties and processability characteristics of pulp and paper. These properties and characteristics include consistency, freeness, contaminant analysis, densometry, porosity, smoothness, softness, fiber analysis, water absorption, wear or abrasion characteristics, and wettability. Pulp and paper testers often differ in terms of display type and special features. Devices and systems may come equipped with an analog meter, computer interface, digital readout, integral software, or video display.
Pulp and paper testers are used in consistency measurements and contamination analysis. Consistency is the amount (%) of dry solids or fibers in pulp or paper stock. It determines how the pulp is formed and processed into paper. If the pulp’s consistency is too thin or too thick, the paper web will not form properly. Contamination analysis determines the amount of stickles, dirt, inclusion, slag, shives, swarf, grinding debris, and other contaminants in a material. The amount of shives, dirt and stickle in pulp or paper can influence processability, an important consideration when selecting pulp and paper testers.
Densometers are pulp and paper testers used for measuring porosity, air-permeability or air resistance of sheet-like or bulk materials such as paper, woven cloth, porous plastics, nonwovens, textiles, filtration media, and membranes. Densometers determine the time required to drive a fixed, known volume of air through a sample. Some densometry instruments also provide smoothness and softness indications by measuring permeation. Pulp and paper testers for fiber analysis and flammability measurement are also available.
Some pulp and paper testers are used to measure freeness, gas and vapor permeability, and contact or wetting angles. Freeness or drainage rate is the speed at which water can be removed from pulp. The inverse is slowness. With pulp and paper testers, the degree of freeness or slowness is controlled by the amount of beating or refining applied to the pulp. Gas and vapor permeability is the ability, or measurement of a sample's ability, to transmit vapors or gases. Oxygen transmission rate (OTR) and water vapor transmission rate (WVTr) are important measurements. Liquid permeability is the ability, or measurement of a sample's ability, to transmit liquids. Contact or wetting angles measure wettability.