Conservation research on Wiang Ta Murals, Mae Fuh Luang Cultural Park, Chiang Rai, Thailand, December 2023. L to R: Nattawan Worawannotai, Gunn, Nicole Tse

Creative Solutions for Conservation Challenges in Thailand

The University of Melbourne has been collaborating with Silpakorn University, Thailand, since 1995. Most recently, a Memorandum of Understanding was signed between University of Melbourne’s Faculty of Arts and Silpakorn University’s Faculty of Science and Faculty of Painting, Sculpture and Graphic Arts. In March 2023 the University of Melbourne hosted an Incoming Research and Training Visit for residents of Silpakorn University’s Faculty of Science. During the visit, Assistant Professor Sutinee Girdthep and Dr Nattawan Worawannotai presented their work on the conservation of Thai heritage. Recent Master of Cultural Materials Conservation graduate Gen Schiesser reflects on the presentations below.

Nature has a specific way of informing our practices. When it rains, we bring in the sheets. The weather forecast tells us how to dress and the climate determines what we can grow. We might eat more salads in the summer and cook more soup in the winter. We are constantly mitigating and navigating nature. We adapt because it is critical and vital and because we know that the variable forces of nature will outlast us if we do not.

Nature, in many such cases, is also the reason for our ingenuity. We make umbrellas to walk in the rain and air conditioners to keep us cool. At Silpakorn University, scholars are working to find ways to apply science to solve real-world problems, including those linked to the preservation of art and culture in different natural environments. Assistant Professor Sutinee Girdthep (Nan) and Dr Nattawan Worawannotai (Nat) are investigating ways to slow damage to Thailand’s most significant monuments and artworks, including the nineteenth-century Wiang Ta murals and the mosaics on the Phra Maha Dhatu stupas. Instead of seeking to control nature, Nan and Nat look to creative, less invasive solutions based on a deeper understanding of the materials, their origins and context, and their environment.

Visit to Australia and signing of the MOU with Silpakorn University, March 2023. Back, L to R: Dr Jitnapa Sirirak, Professor Tim Lynch, Assistant Professor Panupun Limpachayaporn, Assistant Professor Sutinee Girdthep. Front: Dr Nattawan Worawannotai (L), Associate Professor Nicole Tse (R)

Conservation in Humid Climates

Thailand is a humid country, experiencing an average of 60 to 80 percent relative humidity yearly. This level of humidity can be problematic for cultural objects and artworks. The increased water content in the air can cause materials to swell, shrink, rust, and grow mould. The thermal properties in materials can also change, causing objects that are usually hard or ‘glassy’ in colder temperatures (e.g., wax and glues) to soft, rubbery, and viscous when warmed. Paraloid B72, for example, is an adhesive used commonly in the conservation of pottery sherds – but only if the temperature remains below forty degrees Celsius.

So much of modern conservation and museum practice tells us to keep our cultural heritage materials within certain relative humidity and temperature ranges. In addition, many conservation materials, such as Paraloid B72, are designed for cooler maintained temperatures. It is worth noting that a lot of conservation knowledge is coming from the larger conservation epicentres of England and Europe, where the climate is temperate and thus, in some respects, more manageable.

In humid and/or tropical climates, it is not always sustainable, affordable or feasible to power HVAC systems. When it comes to protecting cultural heritage, the impact of nature is a real and severe problem and, in places like Thailand, total control over the atmosphere is an impossible goal. Much like Sisyphus pushing the boulder up the hill for eternity, in highly humid environments you may find yourself continuously cleaning mould off artworks only for it to reappear just weeks later.

This is where conservation gets interesting – when it addresses the threaded nature of science, art and the environment. Controlling the temperature and relative humidity of a space is not all we can do to protect our cultural heritage from the intensity of tropical climates. Research undertaken by Nan and Nat is meeting Thai humidity on its own terms.

PhD student Seka Seneviratne working on the Wiang Ta Murals, August 2022. Photographer: Nicole Tse

Understand the Material, Understand How it Deteriorates: The Wiang Ta Murals

The Wiang Ta murals have seen a lot of different weather conditions. Made in Phrae, in northern Thailand, southwest of Chiang Mai, in the nineteenth century, the Wiang Ta murals originally adorned Wat Wiang Ta Mon monastery. In 1988, the murals were moved to Mae Fuh Luang Art and Culture Park in Chiang Rai. Some areas of the murals are missing colour and water damaged, having been exposed to rain at various points.

For Nat, the Wiang Ta murals were of special scientific and cultural significance, partly because they had not been restored before. As a result, they contain valuable information on the original Thai pigments used in the nineteenth century, pigments for which limited documentation and scientific studies currently exist.

The Wiang Ta Project brought together numerous professions, a testament to the highly collaborative and interdisciplinary nature of conservation. Traditional Thai artists were consulted for oral histories and insights into painting techniques. Structural architects, wood conservators, and art historians were also consulted over the course of the project.

The goals of the project were to understand the painting’s characteristics, history, condition, and degradation processes and to determine what pigments were used in the painting. Ultimately, the Wiang Ta Project wanted to show cultural materials as more than how they appear: they are a combination of local and imported materials, such as pigments. Technological analysis can tell us how different materials were used, what their social importance was, and how to preserve them for the future.

Multi-spectral imaging of the Wiang Ta Mural, December 2023. Top image: Nicole Tse (L) Dr Nattawan Worawannotai (R). Bottom left image: Dr Nattawan Worawannotai. Bottom right image, clockwise from top L: Dr Nattawan Worawannotai, Gunn, Nicole Tse Assistant Professor Sutinee Girdthep. Photographer: Nicole Tse

The mural itself consists of four wooden panels and represents the Lanna school of painting associated with northern Thailand. Each panel comprises three layers: the wood substrate, the ground layer, and the paint layer. Microsamples were taken from the paint layer and analysed under scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), a form of scientific examination that magnifies surfaces and detects chemical elemental presences. SEM-EDS is commonly used in the conservation research world for this purpose due to its unique ability to pinpoint and visualise the location of certain elements and their relationship to one another.

The analysis found that the pigments used in the construction of the mural included lead white, bone black, cinnabar, vermillion, synthetic emerald green, synthetic ultramarine and gold leaf. The ground layer was made from aluminium silicate clay.

The results indicated that a large number of the pigments were likely traded and imported from China, while others were locally sourced. In particular, the clay-based pigments and ground layer may reflect local material due to the high clay content found in Thai soil.

The most interesting findings, however, related to the green pigments vermillion and emerald green. These had suffered the most damage compared to the other pigments, possibly due to fluctuations in relative humidity and temperature across the year and the presence of water soluble binders.

Moisture be Gone: The Phra Maha Dhatu Stupas

Phra Maha Dhatu Naphamethinidon and Naphaphonphumisiri Pagoda, Doi Inthanon National Park, Chiang Mai Province, Thailand, 2013. Photographer: JJ Harrison via Wikimedia Commons

The Phra Maha Dhatu stupas are complex built features. There are two stupas onsite: Phra Maha Dhatu Nabhamethanidol (the King stupa) and Phra Maha Dhatu Nabhapolbhumisiri (the Queen stupa). The King and Queen stupas were built in the Doi Inthanon National Park, southwest of Chiang Mai, in 1987 and 1992 respectively. At sixty metres high, they are under the care of the Thai Air Force. There are no conservation or cleaning problems associated with these stupas that are located on the highest land in Thailand, in conditions of high relative humidity, and whose exteriors feature intricate mosaics of varying material complexity.

Just kidding!

The price of this visually stunning, structurally brilliant built heritage is all else that follows: the high cost associated with maintaining it; the logistical issues that come with said maintenance; and the lack of preventative measures that might enable breaking the Sisyphus-and-the boulder circuit of continuous, rigorous, and exhaustive management and conservation for recurring issues. The hill never ends. The boulder never reaches the top. And you can’t landscape the hill away with a bulldozer.

The bulldozer might sound dramatic, but in a sense this is what conservators try to do when they manage objects that are housed inside buildings. The ‘hill’ that is conservation problems caused by the environment – pests, rust, mould, warping, fading – can be ‘bulldozed’ through the implementation of measures that control the environment – air conditioning, humidity control, ventilation, UV-sensitive glass. You still have to push the boulder by monitoring the condition of cultural objects often and ensuring that the preventive measures remain in place, but the path is easier because it is flat.

Measures of this kind are not an option, however, when it comes to objects that are exposed to the elements –  at least, this has been the usual thinking. But this is where Nan’s research comes into play. Nan’s work is aimed at mitigating the fungal and algae staining occurring on the stupa mosaics as well as the erosion of the mosaic fillers from rain that causes some of the mosaics to periodically come loose. Nan developed an innovative plan for addressing these issues: to formulate a hydrophobic surface spray for the mosaics, an idea which resulted in a unique collaboration with Silpakorn University and the Thai Air Force.

The hydrophobic surface spray was rigorously tested: it needed to dry clear so as to not detract from the mosaic feature; it needed to be acid, UV and water resistant; it needed to be temperature resilient; and it needed to prevent the growth of fungi and moss.

Nan found that the best hydrophobic coating was a polyurethane resin with silicon dioxide nanoparticles which fit all of the above criteria. Currently, a small area of each stupa is being used to test the coating. If successful, after a year the hydrophobic surface spray will be applied to the entire built surface.

Only the Beginning

The research undertaken by Nat and Nan represents two important stages in the conservation of cultural heritage. The first stage, demonstrated through Nat’s work on the Wiang Ta murals, shows how before any remediation work is used on an object or surface, the nature of the materials must first be understood in the context of where they are from. The second stage, demonstrated through Nan’s formulation of the hydrophobic surface coating, shows the creative process of planning conservation remediation that meets the environment the material exists in on its own terms.

We look forward to hearing about more materials studies and conservation treatments that occur in tropical environments from the wonderful academics at Silpakorn University.

Research at the Grimwade Centre with Silpakorn University visitors, March 2023

Thank you to Assistant Professor Sutinee Girdthep (Nan) and Dr. Nattawan Worawannotai (Nat) for sharing with us their research and for their continued collaboration and commitment to conservation science. As part of each presentation, the following groups were acknowledged for their contributions to the projects:

    • Mae Fuh Luang Foundation
    • Faculty of Science, Silpakorn University
    • Teerpat Khanjao
    • Royal Thai Air Force
    • Royal Thai Air Force Academy

I would like to also acknowledge and thank Associate Professor Nicole Tse for hosting the presentations and for providing information on the history of the University of Melbourne’s relationship with Silpakorn University.

Following on from a visit in March 2023, Assistant Professor Dr Sutinee Girdthep and Titichaya Limpathompipop joined the Grimwade Centre to continue our research collaborationand enrol in select subjects in the Masters program. The visit is supported by a grant awarded to Silpakorn University, Science-based Conservation of Artworks (2022) and Science Learning Activities through Workshops on Art Conservation and Collection of Documentary Knowledge on Conservation of Thai Art to Promote the Creation of Science Courses for Conservation Work (2023), funded by the National Research Council of Thailand, Ministry of Higher Education, Science, Research and Innovation, and an Memorandum of Understanding between the Faculty of Science, Silpakorn University, and Faculty of Arts, University of Melbourne (2023–2028).

Together we have been investigating The Study of Characteristics and Polymer Properties of Materials used as Binders in Traditional Thai Painting with Tempera Technique by Scientific Process, with the sampling, ageing and PyGCMS analysis with Alex Duan, Traces in the School of Chemistry. Assistant Professor Dr Sutinee Girdthep and Titichaya Limpathompipop have also joined Nicole Tse in SHAPS to do some pXRF analysis of Traditional Chinese Medicines at the Golden Dragon Museum in Bendigo as part of a current Masters student’s minor thesis project, Qiyin Zhuang, and also micro fading tests of paint samples aged in the Philippines and Australia.

At Traces, University of Melbourne. L to R: Dr Alex Duan, Melbourne TrACEES (Trace Analysis for Chemical, Earth and Environmental Sciences) Platform, and from Silpakorn University, Titichaya Limpathompipop and Assistant Professor Dr Sutinee Girdthep, with SHAPS Masters of Cultural Materials Conservation Student Supansa Thongsuk, investigating binders in traditional Thai painting with Pyrolysis GCMS