COMPARISON OF THE OPTICAL-PROPERTIES OF RADIATA PINE TMP AND CTMP PULPS AND THE STARTING WOOD

The reflectivity, specific light scattering coefficients and specific light absorption coefficients of earlywood and latewood in each ring f rom three radiata pine discs were determined at 457 nm. Significant ri ng-to-ring and within-ring variation was observed. A method was develo ped to determine the light absorption spectra of the wood. Comparison with that of TMP pulp showed that during refining a chromophore with a maximum absorption at 430 nm was produced. It is suggested that this is the same chromophore as that produced during light-induced yellowin g of mechanical pulps, possibly an o-quinone. Chromophore formation wa s less when sulfite was present.