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TAPPI T 579-2012 (R2018)

Diffuse brightness of paper, paperboard and pulp (d/0) (ultraviolet level D65)

This method determines the brightness of white, near-white, and naturally colored pulp, paper, and paperboard. Brightness is a commonly used industry term for the numerical value of the reflectance factor of a sample with respect to blue light of specific spectral and geometric characteristics. This method requires an instrument employing diffuse illumination and 0° viewing geometry  This method is applicable to all naturally-colored pulps, and papers and board made therefrom. The measurement is not suitable for paper or paperboard containing added coloring matter (such as yellow or green dyestuff) which appreciably absorbs light in that part of the spectrum extending from about 400 to 500 nm. This brightness method is not applicable to colored papers.  Pulps to be tested are made into handsheets prepared according to TAPPI T 218 “Forming Handsheets for Reflectance Tests of Pulp (Büchner Funnel Procedure)” or T 272 “Forming Handsheets for Reflectance Tests of Pulp (Sheet Machine Procedure).” This method may also be used to measure the brightness of machine-dried sheets.

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Technical Association of the Pulp and Paper Industry [tappi]

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