Hanji's molecular weight and effect of Dochim on Hanjis properties

Hanji is a traditional Korean handmade paper, which has been known in ancient Far East as excellent quality calligraphic paper for more than 1,500 year. Hanji is mostly made of Korean paper mulberry bast fibers, and if properly processed, normally lasts for more than 1,000 years with significant strength and still recognizable calligraphic writings or drawings on it. We measured the viscosity of the dissolved celluloses of the paper mulberry bast fibers of different levels of artificial aging to know the cellulose molecular weight changes. Cellulose dissolution was made by CED method. The viscosities of the Hanjis that experienced the artificial aging were compared to those of the Hanjis that were made hundreds years ago. We could interpolate the viscosities of the time-aged Hanjis in the our artificial aging curve. Dochim is a special way of Hanji calendering, but is turned out to be quite different from modern calendering (machine calendering) in several aspects. Compared to the modern calendering, Dochim increased paper gloss much more, but paper smoothness much less. In Dochim process, mechanical impact were applied vertically to the surface of papers. By the process, densification occurred and the degree of densification was very much dependent upon fiber sources.