Abstract
Hanging scrolls are a traditional form of Japanese ornamental art used to display paintings and calligraphy. When displayed, scrolls are unrolled and hung straight, without rippling or warping, on a wall or in an alcove. When stored, they are rolled up smoothly and tightly from the bottom. To make possible the effective performance of these two functions, paintings and calligraphy depicted on pieces of silk fabric or paper have typically been backed with four layers of traditional Japanese paper affixed through the use of a paste made from wheat starch. In order to maintain the flexibility of scrolls, the wheat starch used for backing is fermented for ten years. This process reduces the molecular weight of the paste, as the starches break down allowing the paper to remain flexible after drying, but it also reduces the adhesiveness of the paste. Since its adhesive strength may therefore be insufficient, scroll makers came to use a technique of lightly beating the surface of each layer of lining paper with a special "beating brush," in order to provide better adhesion. There is an inherent risk of damaging the paper or the work underneath when beating the lining papers, if it is done too strongly. On the other hand, if it is done too weakly, it cannot enhance the strength of the adhesion. Accordingly, although this beating work appears to be a simple process of merely rapping the brush up and down, in fact it requires a high level of technical ability. Generally, while experts are able to remain steady when doing this beating work even over long periods of time, non-experts often indicate that they feel fatigue in the upper right arms by which they hold their brush. In this study, we designated an expert and a non-expert as test subjects and measured the muscle movements of nine muscles in their upper right arms as they maneuvered their brush. The purpose of this measurement was to separately elucidate each muscle movement made by the expert and the non-expert. Furthermore, this study also verifies the muscle fatigue of each subject by calculating the percentage of maximum voluntary contraction, %MVC. By supporting the assumption that compared to a non-expert an expert can carry out the work more efficiently through the measurement results - which showed clear differences in the subjects' muscle movements and muscle fatigue - we hope to contribute to developing technical skill acquisition guidelines for non-experts.
