Light-fast Performance of Coated Handmade Papers

The purpose of the study was to prepare Fenglachien papers, a kind of high-caliber coated paper mostly for Chinese calligraphic use made of coated handmade paper. The parameters studied for the coating and color formulations included the base papers, white complex pigments, various hued pigments and their concentrations, binders, and additives such as a wax emulsion, an insolubilizer, and a photostabilizer. All coated papers were evaluated for their light-fastness through UV irradiation, as this is one of the most important preservation characteristics for colored Fenglachien papers. We also tested the light-fastness of glossy golden- and silver-colored pearlite pigments used for color-painting and pattern-printing on the coated papers. The results indicated that the 2 kinds of base papers performed differently in terms of the white and colored pigments. The colored pigments interacted with the binders in complicated ways, and there appeared to be no rule for the changes observed. For the same colors, a more-saturated hue had better light-fastness than a paler hue. Among the white pigments, precipitated silica had the best light-fastness performance, while titanium dioxide fared the worst. The wax emulsion and insolubilizer contributed positively to the light-fastness of the Fenglachien papers. The tested photostabilizers, however, did not appear to have the anticipated efficacy. Certain synthetic golden pigments showed good light-fastness that allowed for the substitution for actual gold foil flakes for pattern-printing of Fenglachien graphic designs.