Effects of Fines on the Fiber Length and Coarseness Values Measured by the Fiber Quality Analyzer (FQA)

Instruments for optical fiber measurements, such as the Fiber Quality Analyzer (FQA), are widely used to measure various properties of pulp samples. For the evaluation of market pulps, the pulp properties of interest are fiber length, coarseness, and fines content. Fiber length and coarseness are often used to determine which pulps are suitable for producing particular products. The objectives of this research are 1) comparison of fines content as measured by the FQA and Britt Jar (TAPPI test method T261), and 2) determination of the relationship between the fines content and the fiber length/coarseness measurements. Over 40 samples bleached kraft and chemithermomechanical market pulps were evaluated for fines content, fiber length, and coarseness using the FQA and Britt Jar methods. The FQA measurements were performed on whole pulp samples and fine free samples to provide length weighted fines percentages, length weighted length and coarseness measurements, while the Britt Jar measurements provided a mass percentage of fines. The aforementioned values for multiple samples in each category allow for a unique comparison of fines’ effects on fiber length and coarseness values. Fines affect the length weighted length and coarseness values for different grades of pulps.