AQUEOUS LIGHT BLEACHING OF PAPER: COMPARISON OF CALCIUM HYDROXIDE AND MAGNESIUM BICARBONATE BATHING SOLUTIONS
TERRY TROSPER SCHAEFFER, VICTORIA BLYTH-HILL, & JAMES R. DRUZIK
ABSTRACT—The immediate and long-term effects of aqueously light bleaching both unsized and gelatin-sized cotton cellulose papers in either calcium hydroxide, Ca(OH)2, or magnesium bicarbonate, Mg(HCO3)2, solutions were investigated. After samples were treated by washing, bleaching, or control bathing in the dark, one-half of each was artificially aged, and the condition of all samples was assessed. Appearance was analyzed by reflectance spectrometry, tensile behavior was observed using stress-strain measurements, and pH and gelatin content in the papers were measured with modified Tappi standard measurement procedures. the results showed that exposure to light per se during the bleaching process did not adversely affect the properties of the papers. It appeared that aqueous light bleaching of the unsized paper was equally effective in either solution. The visible changes in appearance, as well as alterations in other properties of the gelatin-sized paper, were influenced by the partial removal of sizing upon immersion. Finally, a clear preference for calcium hydroxide or magnesium bicarbonate as the bathing solution for aqueous light bleaching was not suggested by the results of the limited number of experiments possible in this study. Thus the choice of immersion solution should be made on an individual basis.
2. MATERIALS AND METHODS
2. B. ANALYTICAL PROCEDURES
a: Appendix , Materials , References , Author Information