As part of her master’s thesis, engineering student in chemistry and materials Lise Vermeersch is looking for a way to make the gold leaf of the famous Shwedagon pagoda in Yangon, Myanmar, adhere better. The stupa “also called golden robe” of the temple is covered with 50 tons of gold leaf, glued to an underlying copper structure. Over time, however, the gold plates flake off, so the temple has to be renovated every five years. “There are a number of possible causes for the gold detaching. It is not easy to glue two totally different metals together. When it gets very hot, for example, the glue, copper and gold expand differently, creating mechanical tensions that cause the glue seal to break. The temple is also close to the sea – copper can oxidise under the gold leaf, so corrosion may start that causes the glue to detach”, says Vermeersch.
The Shwedagon Pagoda in Yangon, Myanmar, is one of the most important Buddhist stupas in the world. Inside the temple there are said to be eight hairs of the Buddha Gautama, and about 1,500 people work there each day. The 98m high gilded temple is visible throughout Yangon, day and night. The crown is tipped with 5,448 diamonds and 2,317 rubies and8,688 sheets of f gold leaf is needed to completely cover the temple. This gold is glued to the underlying copper structure.
The five-yearly dismantling of the dome is a costly affair, but the stupa is so important to Buddhist pilgrims that the costs are considered reasonable. The many pilgrims who visit the sanctuary every year contribute as much as possible to its maintenance. Because of the amount of gold needed for restoration, the administrators of the temple even have their own small gold factory nearby.
A collaboration with Yangon Technological University (YTU), the local museum and Myanmar’s minister of culture with the Vrije Universiteit Brussel came about at the request of a Shwe Wut Hmon Aye, a former PhD student of Professor Herman Terryn who is now working at YTU. Within this collaboration a research project was set up to study the deterioration of the gold/polymer/copper interfaces. Vermeersch and fellow engineering student Wouter Vereycken wrote their master project on this subject. Vermeersch is now working on it and, under the supervision of Professor Terryn and Professor Tom Hauffman, is investigating preparations for the roof and trying to find out why the structure is failing.
There are a number of possibilities: it may be that a galvanic coupling is created by the adhesive; the warm climate and the location of the temple next to the sea may take their toll; or the glue used may be insufficient. The bonding of gold leaf is often done for cultural heritage, but research into the chemical background remains limited. A connection between copper and other materials with glue is mainly done in the production of electronics, such as printed circuit boards. Both materials therefore still require research into their adhesive properties in this setting. Most metals and metal oxides are coated with an organic coating to protect them from dangerous environmental influences that can cause corrosion and to give them certain functionalities such as gloss, colour or electrically conductive surfaces. The durability and efficiency of such hybrid structures is largely determined by their molecular interfacial behaviour. The aim is to study the molecular gold/polymer/copper interfaces and to correlate them with the behaviour of the gold/adhesive/copper used in the Shwedagon Pagoda. If it is possible to determine the cause, one can look for lasting solutions.