| Research Abstract |
Lead glass pigments ("Shin-iwaenogu" are one of the most popular painting materials for Japanese style paintings. We examined the discoloration of lead glass pigments.
First, we confirmed that there were dark silver gray parts on the picture of lead glass pigments. In this part, PbS has been detected. The picture had foundation layr of HgS.Possibly, lead glass interact with S^<2-> from HgS.
Next, we examined what various gases influence lead glass pigments (sample colors : pink, yellow, green, pale blue, and gray)
* SO_2 10ppm, high humidity, 20ﾟC,20 hours
Yellow color turned to brown, gray color changed to ivory, and other colors were brighten. Various product may have formed on pigments.
* H_2S 10ppm, high humidity, 20ﾟC,20 hours
All colors were dark-browned. Some sulfides may have formed on pigments.
* Formaldehyde 25ppm, high humidity, 20ﾟC,20 hours
Changes of color were not confirmed.
At 1) or 2) cases, foundation layr of chalk have playd the part of buffer to acid gases.
After 1) experiment, we try to recover, using O_3. Pale blue and gray pigments recovered their blueness slightly. But some blurs remained on surface of test panel.
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