TEACHING THE SCIENCE OF
HERITAGE CONSERVATION

HKU’s Architectural Conservation Laboratory is educating students and the community about the nitty-gritty of preserving heritage buildings in Hong Kong. It also provides scientific analysis for heritage projects in the community.

Most people would agree it is important to protect Hong Kong’s few remaining heritage buildings.
But even among conservation managers and students, there can be limited understanding of what this means in practice.

Dr Gesa Schwantes, Director of the Architectural Conservation Laboratory (ACLab) in the Faculty of Architecture, has had fourth-year students who cannot tell the difference between concrete and lime plaster, and seen clients ignore her advice to use mineral-based paint, not latex paint, resulting in damage to historic plaster.

It was situations like these that inspired the Faculty to launch the ACLab and recruit Dr Schwantes to lead it. The ACLab provides contract research and a springboard for teaching students the basics about the science of conservation.

“Conservation students learn a lot about heritage values and the significance and history of a building and this is all very important. But they also need to understand how important it is to look at the materials and building fabric in order to understand defects and how to fix them,” she said.

An opportunity to demonstrate the problems was recently handed to Dr Schwantes when her laboratory was contracted to do preliminary analysis of paint and plaster finishes at Pun Uk Mansion, a 1930s Hakka building, which she extended into a teaching and knowledge exchange activity.

Proportionate to the task

She was brought into the project by consultant MSc(Conservation) graduate Curry Tse, whose client wants to restore the 600-square-metre structure and build a columbarium next to it. The mansion includes an ancestral hall, courtyards and side buildings, and it has a good variety of decoration styles, including wood, carved wood, plaster and plaster relief.

However, the building has major damp problems due to a hole in one of its roofs and poor drainage that means it can be standing in 30 centimetres of water for days after a heavy rain.

Dr Schwantes brought fourth-year BA(Conservation) students there in autumn 2018 to expose them to real-life challenges in building preservation and the techniques involved in analysing buildings.

The students were put to work investigating and drawing details of the building. They were taught how to collect samples and where to collect them and shown how to use specialist equipment to analyse the results. The work was carefully supervised because of the need to avoid causing damage and to be proportionate to the task at hand – for some tasks, such as infrared testing, a tiny sample the size of a couple of sesame seeds is sufficient, while others, such as mortar analysis, require a sample of up to 500 grams.

In the laboratory, she showed them how to prepare samples for cross-sectional analysis. For instance, one process involves pouring liquid resin into a silicone cube, adding the sample,
letting it harden, then cutting and polishing it before looking at it under a microscope. “The idea is that students see every step of the process – what liquid resin is, how we mix it, how long the process takes. This will help them later if a client says the analysis is too expensive– the student will know it takes a day to do this in the laboratory which justifies the price. That’s important information for them,” she said.

Reporting to clients and the community

The class were also fortunate to have access to a similar building for comparison, the ancestral home of student Kitty Lam Pui-yee, who found the course personally and professionally enriching. “It has allowed me to understand my family heritage by comparing Pun Uk with my grandma’s Hakka house and it really raised my interest in traditional Hakka decorations. I am developing my thesis on this,” Kitty said.

The students’ work has helped provide input to a report on the Pun Uk Mansion by the ACLab that recommends the client repair drainage and the roof and provides specific analysis of the building’s materials and how to restore them.

“We are the only laboratory doing this kind of materials analysis and interpretation in Hong Kong outside of government. Other laboratories can tell you about the materials, but we will provide information on how to conduct repairs and treat the building better,” Dr Schwantes said, a lesson also imparted to tomorrow’s architectural conservationists.

She also hopes to educate the public on the value of this approach to conservation through a knowledge exchange project centred on Pun Uk Mansion. A website is under construction that will provide information on built heritage conservation and 3D drawings of the mansion, with text and photos and videos explaining the work done by Dr Schwantes and her students. Students are involved in providing drawings for the website, which will be launched in summer 2019.

​ We are the only laboratory doing this kind of materials analysis and interpretation in Hong Kong outside of government. Other laboratories can tell you about the
materials, but we will provide information on how to conduct repairs and treat the building better.

Dr Gesa Schwantes

Dr Schwantes with students at Pun Uk Mansion, learning first-hand about the real-life challenges in building preservation and the techniques involved in analysing buildings.

(Courtesy of Alison Trachet)

One group mixing lime plaster with red pigment and brick powder in the laboratory to compare the visual differences between these stained plaster dummies in comparison with the plaster at Pun Uk.

A group of students studying traditional Hakka roofing techniques and documenting the defects at the roof of
Pun Uk Mansion.

(Courtesy of Yumi Li Yeung-shin)