Visualization of Brushing in “Shibo” Production of Hand-Made Japanese Paper

We deal with “Danshi” that has a special wrinkle called “Shibo” on the surface structure of the Japanese paper. Three sheets of wet papers are superimposed to make the Shibo. Wet papers are extended the slack by brushing. Superimposed wet papers are made the Shibo by especial pulling movement. This time, we investigate about the movement of brushing for extending the slack. Subjects are two people which are wearing 18 reflecting markers on the body. An expert has manufactured Danshi for 23 years of experience and a non-expert has done less than 1 year of experience. The movement of brushing process is measured as sampling time of 100 [Hz]. We will investigate differences of the physical movement between the expert and the non-expert. We make a hearing about the differences and work on visualization about the skill of the expert. The method of making Shibo structure has five procedures. First, one piece of wet paper is placed on the inclined work table. Second, wrinkles of the paper are extended by brushing. Third, next wet paper is put on the first sheet, it is extended the slack again. Fourth, moreover third wet paper is put on the second sheet, it is extended the slack by brushing again. Fifth, the Shibo structures are produced by pulling in a state of three superimposed sheets. We compared the number of brushing in each sheets. There was not difference in the number of brushing in each sheet in a non-expert. In other hand, number of brushing by the expert was two times that of first and second sheets in third sheet. The number of brushing in first and second sheets did not change by the expert. In consequence, he was a notion that important things for making the clear Shibo structure are not only extending the slack, but also pulling out the bubbles. We divided brushing movement into eight directions. In third sheet of the expert, the number of brushing to body direction has increased over 10%. It was found that the expert removed air bubbles from the corner of the top right. Furthermore, we investigated the change of angle of the right wrist in the expert and the non-expert. It became clear that angle of the wrist is reduced when the expert is brushing forward.