Studies on the Stability of Binding Media in Retouching Materials for Exterior Painted Wooden Decoration in Taiwan

Abstract

The conservation of tradition polychrome in Taiwan adopted Western techniques from the beginning of twentieth century. However, the issue of whether such materials are suitable to the climate of Taiwan is a question that remains unanswered. The objective of this study was to assess the durability of three retouching binders under the external climate conditions of Taiwan. The binders that were tested included a watercolour coated with 5% acrylic resin Paraloid B72, an acrylic resin Paraloid B72 and a low molecule weight resin Laropal A81 using accelerated aging conditions that simulated the exterior climate of Taiwan. Alterations in colour, gloss, adhesion and solubility were measured to evaluate the stability and reversibility of the materials. The results showed that both watercolour coated with 5% Paraloid B72 and Laropal A81 had lower resistance to moisture, and thus are not recommended for use in exterior areas in Taiwan. Paraloid B72 remained more stable with good re-treatability after ageing, however it was still affected by UV/heat and condensation cycles. The observation of material behaviour in the study provides information for the selection of retouching materials for exterior Taiwanese traditional polychrome, and highlights the need for further systematic testing of suitable materials in the future.

KEYWORDS:

• Polychrome conservation
• Exterior polychrome in Taiwan
• Retouching material
• Binder stability

Acknowledgements

Special thanks to the certificate company SGS TAIWAN LIMITED, who provided the equipment and support to this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Wen-Yuan Lee

Wen-Yuan Lee obtained her master's degree in 2011 from the Graduate Institute of Conservation of Cultural relics and Museology in Tainan National University of the Arts, Taiwan. During her studies, she participated many conservation projects of traditional Taiwanese polychrome. She later joined Chimei Museum, Taiwan in 2012 as an oil painting conservator, and stared her Ph.D. program in the Department of Fine Arts of National Taiwan Normal University in 2017. From 2022, Wen Yuan became an assistant research fellow at the National Taiwan Museum of Fine Arts, focusing in the conservation and technical studies of oil paintings.

Cheng-Huang Lin

Cheng-Huang Lin received his Master's (1991) and PhD degrees (1994) from Kyushu University (Applied Chemistry), and then remained at that institution as a Research Assistant until 1996. Following this, he continued his research career as a postdoctoral fellow at Iowa State University in the USA. He returned to Taiwan in 1998, where he was appointed an Assistant Professor at Chaoyang University of Technology. Shortly after this, he was appointed an Assistant Professor at National Taiwan Normal University, where he was promoted to the rank of Professor in 2005. After almost 30 years chemistry carriers, he transferred to Department of Fine Arts at same university. Right now, his research interests focus on the applications of Raman spectroscopy and Mass spectrometry for use in the analysis of paintings, and developing new methods for conservation science.