Keywords

1 Introduction

There are various traditional crafts in the world. For example, the pottery art and metal work exist in the various countries, their works and products are made in an original way based on the culture. There are many traditional crafts in the same way. Urushi crafts is a representative traditional crafts in Japan. When an alternate current between East and West had started in the Age of Discovery, the porcelain had been called “china”. It was the representative traditional crafts in China. On the other hand, a lacquer ware had been called “japan”. “Urushi” is a resin from Japanese lacquer tree. It has been used as a paint, artists’ paint and adhesive material in Japan, China, Korea and South-East Asian countries. In the Urushi crafts, a wooden basis is made from various woods, and it was painted by Urushi resin several times. As necessary, it is decorated by a metallic powder in Japan. It is called “Maki-e”. Urushi crafts work had been preferred in Europe because of its beauty and quality, the royalty and the aristocracy collected the Urushi crafts work. Many of them have been passed down as an art object in Europe now. Good Urushi crafts work had made in various periods in history in Japan, and it has been kept by the policymaker, shrine, temple and a person on the street.

Urushi crafts work is damaged and Urushi comes off over a course of a long period of time. But Urushi craft work can be repaired, and Urushi resin can be painted once again. Therefore Urushi craftspeople learn how to make and repair the Urushi crafts work. There are many Urushi crafts works in the museum and art museum. Many persons on the street keep them. These works has been repaired repeatedly by Urushi craftspeople. Urushi craftspeople need to identify the characteristics and conditions of the work when it is repaired because they can’t repair the work appropriately. When the craftspeople identify the characteristics and conditions of the work, they observe the work by the naked eye. This observation technique is called “Mitate”. Expert Urushi craftspeople can identify the many characteristics from the work, and use it to repair the work by conducting Mitate. It was shown that the expert Urushi craftspeople jiggle the work up and down when they conduct the Mitate in the previous research [1–3]. It seems that they can identify the characteristics by observing the change in appearance of the surface of the work with jiggling it up and down. This research aimed to know difference of a motion of the Urushi crafts work between the expert Urushi craftspeople and the non-expert Urushi craftspeople when they conduct the Mitate.

2 Measurement

2.1 Subject

There were two Urushi craftspeople as a subject in this research. They specialized on the Maki-e technique. Subject A was 59 years old, male and his year of experience was 41 years and 10 months. Subject B was 25 years old, female and her year of experience was 3 years and 10 months. Subject A was regarded as an expert because he had a high level of Meki-e technique and had many disciples. Subject B was regarded as a non-expert because she was the craftspeople under training.

2.2 Maki-e Specimen

Figure 1 showed a Maki-e specimen. Expert (Male, 58 years old, 39 years of experience) made these specimens. Size of specimen was 70 mm × 70 mm × 5 mm. Its base was PMMA (Polymethylmethacrylate) board. Its board was polished by a sand paper, rubbed with raw Urushi. After that, black Urushi (Kuro-Roiro-Urushi, made by Shikata Yoshizo Urushi Ten) was painted on the surface of the PMMA board in twice. After hardening the black Urushi, the surface was polished by the charcoal, and rubbed with Uwazuri Urushi (Reddish clear Urushi). After that, rough design was drawn by the bengal red Urushi (E-Urushi) and gold round powder was sprinkled on the rough design. This decoration method was called “Maki-e”. Maru-fun (Round shape powder, made by Asano Shoten) was used in these specimens. As the number of Maru-fun was more increased, the size of powder was bigger. The type of metal was gold, and its number was 2, 6, 8 and 14 in this research. These powders were sprinkled on the 40 mm diameter round shape.

Fig. 1.
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Maki-e specimen

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2.3 Condition of Mitate

Figure 2 showed a measurement scene. Figure 3 showed a measurement position. The light of measurement room was turned out. One light source was set in front of the subject. The light source was the TOSHIBA NEOBALL Z ReaL (EFA10EN/8-E17-S, made by TOSHIBA LIGHTING & TECHNOLOGY CORPORATION). The color was neutral white. The angle between the light source and the vertical line of specimen was 60 degrees. The distance between the light source and floor was 2000 mm. Figure 4 showed the specimen position on the frame. Four specimens were set in a straight line on the frame fixed in the tripod. The specimens were arranged in order of No.6, No.2, No.8 and No.14 from left side. The illuminance at the specimen was 768 lx (measured by Digital Lux Meter 51001 made by Yokogawa Meters & Instruments Corporation). The distance between the specimen and floor was 960 mm, and the distance between the specimen and the light source was 2420 mm. Firstly the subject sat on a chair, the angle between a subject eye and the vertical line of specimen was 60 degrees. The frame on the tripod could be made a 360-degree turn by the subject. When the subject observed each sample, they were directed to set their eye, specimen and the light source in a straight line. Observing time for each specimen was not restricted. The subject could move the specimen free. When the observation of each specimen was finished, the subject was directed to arrange them in order of the number of gold powder.

Fig. 2.
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Measurement scene

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Fig. 3.
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Measurement position

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Fig. 4.
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Specimen position on the frame

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2.4 Motion Analysis

A motion of the subject and specimen was measured by the MAC3D System (made by Motion Analysis Corporation). Infrared rays were emitted by the infrared camera. The rays were reflected on the infrared reflective marker which set on the object, the motion of the marker was caught by the camera. The position of the marker was showed as a coordinate in the three-dimensional space. Figure 5 showed the position of the infrared camera. Four infrared cameras were set around the subject and specimen. Figure 6 showed the positon of the infrared reflective marker. There were 10 markers on the head top and, head right, head left, head front and edge of frame. The markers of head right and frame 2 were analyzed in order to know the vertical motion of the subject eye and specimen in this research.

Fig. 5.
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Infrared camera position

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Fig. 6.
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Infrared reflective marker position

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3 Result

3.1 Order of Observation and Arranged Order of Specimen

Figure 7 showed the observation order in each subject. Expert observed the specimen in order of No.14, No.8, No.2 and No.6 from right side of the frame. Non-expert observed the specimen in order of No.2, No.6, No.8 and No.14, and lastly observed the No.2 once again.

Arranged order of specimen was correct in both the expert and the non-expert.

Fig. 7.
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Order of observation in the Mitate

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3.2 Observation Time in Each Specimen

Figure 8 showed the observation time in each subject. Expert observed the No.2 specimen for 1.20 s, did the No.6 specimen for 1.23 s, did the No.8 specimen for 6.33 s and did the No.14 specimen for 5.00 s. Non-expert observed the No.2 specimen for 7.30 s first time, did the No.2 specimen for 4.73 s second time, did the No.6 specimen for the 16.10 s, did the No.8 specimen for 11.87 s and did the No.14 s for 13.73 s.

Fig. 8.
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Observation time in each specimen

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Fig. 9.
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Frame 2 marker position of expert in each specimen

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Fig. 10.
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Frame 2 marker position of non-expert in each specimen

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Fig. 11.
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Head right marker position of expert in each specimen

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Fig. 12.
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Head right marker position of non-expert in each specimen

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3.3 Motion of Frame 2 Marker and Head Right Marker

Figure 9 showed the position of frame 2 marker in the expert. Vertical axis showed the distance from the floor. Horizontal axis showed the time from the start of the Mitate. The marker did not much move in the case of No.2 and No.6 specimens. The marker moved up and down again and again. Figure 10 showed the position of frame 2 marker in the non-expert. The marker moved up and down strongly once time in the case of No.2 specimen of the first time. The marker did not much move in the case of No.2 specimen of the second time. The marker moved up and down strongly in the case of the No.6, No.8 and No.14 specimens. The marker also moved a little in the case of them.

Figure 11 showed the position of head right marker in the expert. The marker did not much move in the case of No.2 and No.6 specimens. The marker moved a little in the case of No.8 and No.14 specimens. Figure 12 showed the position of head right marker in the non-expert. The marker slightly moved up and down. The marker did not move up and down again and again in the case of the expert and non-expert.

Fig. 13.
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Deviation of frame 2 marker position in each specimen

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Fig. 14.
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Deviation of head right marker position in each specimen

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Figure 13 showed the deviation of frame 2 marker position in each subject. Expert’s deviation was equal to or less than 5 mm in the case of the No.2 and No.6 specimens. It was largish in the case of the No.8 and No.14 specimens, but was equal to or less than 10 mm. Non-expert’s deviation was larger than the expert in each specimen. Especially, it was equal to or more than 20 mm in the case of the No.8 specimens. Figure 14 showed the deviation of head right marker position in each subject. The expert’s deviation was equal to or less than 5 mm in each specimen. The non-expert’s deviation was larger than the expert in each specimen. Especially, it was equal to or more than 20 mm in the case of the No.14 specimen.

4 Discussion

Expert observed the specimen in order from the right side. Non-expert observed the specimen in order of No.2, No.6, No.8 and No.14, lastly she observed the No.2 specimen once again. It seemed that the expert observed the specimen with an open mind, but the non-expert started observing each specimen in anticipation of the number of gold powder.

Expert’s observation time of the No.14 and No.8 specimens was longer than the No.2 and No.6 specimens. Expert observed the specimen while he moved the specimen up and down again and again in the case of No.14 and No.8. It is easier to identify the size of gold powder in the case of No.14 specimen than the other specimens. It seemed that the No.14 specimen was the first specimen in this Mitate, and he identified the number of gold powder. Therefore it took a slightly long time to observe the No.14 specimen. It also took a slightly long time to observe the No.8 specimen, and he moved the specimen up and down again and again because there were many gold powders similar to No.8 like No.5, No.6, No.7, No.9 and No.10. Non-expert did not move the specimen up and down again and again. It suggests that expert identifies the change in appearance of Maki-e surface by the change of a constant up-and-down motion. It seemed that expert did not need to move the No.2 specimen up and down, and did not take a long time to identify the number of gold powder because the appearance of No.2 specimen was obviously different from the appearance of No.14 and No.8 specimens. It was expected that the expert did the same way of No.8 specimen when he observed the No.6 specimen because the appearance of No.6 specimen was similar to the appearance of the No.8 specimen. However the expert did not take a long time to observe the No.6 specimen, and did not move the specimen up and down because it was easy for him to identify the number of gold powder compared with the No.8 specimen. Furthermore, the deviation of the frame 2 and head right marker position were slightly large in the No.14 and No.8 specimens, and it was small in the No.2 and No.6 specimens. It suggests that the expert can identify the characteristics from the change in appearance by the less motion than the non-expert because the deviation of the expert was smaller than the non-expert.

Non-expert had a tendency to take a longer time to observe the each specimen than the expert. Observation time was longer than 10 s in the case of the No.6, No.8 and No.14 specimens. It did not exceed 10 s in each observation of No.2, but total time of twice observations was longer than 10 s. Non-expert had a tendency to take some time to identify the number of gold powder. Non-expert moved the each specimen up and down strongly, but she did not move it up and down again and again like the expert. It seemed that the non-expert could not identify the change in appearance by the constant up-and-down motion like the expert because there were the large and small motions in the observation on specimen. Furthermore, the deviation of the frame 2 marker position was larger than the head right marker position except for No.14 specimen, the non-expert moved the specimen more strongly than her head. However the non-expert moved her head more strongly than the expert. As these results, it suggests that the non-expert mainly moves the specimen up and down like the expert, but the non-expert makes the change in appearance of Maki-e by adding the motion of her head.

5 Conclusion

This research aimed to know difference of a motion of the Urushi crafts work between the expert Urushi craftspeople and the non-expert Urushi craftspeople when they conduct the Mitate. The motion of the specimen and subject’s head were measured when the expert and non-expert Urushi craftspeople conducted the Mitate of the Maki-e specimen. As the results, it is found that the expert can identify the change in appearance of Maki-e surface by moving the specimen up and down a little. Furthermore, he can skip the up-and-down motion and shorten the observation time by comparing one specimen with the other specimen in the case of the different number of the gold powder. Non-expert needs to identify the change in appearance by constant moving the specimen up and down in order to conduct efficient, quick and accurate Mitate.