Japanese conservation experts visit ICUA Zadar

From May 7th to 9th, 2025, the International Centre for Underwater Archaeology in Zadar had the distinct privilege of hosting esteemed experts from Japan. During their visit, they delivered insightful lectures and showcased practical work on various materials, focusing on the latest approaches in the field of underwater archaeological conservation. Their presentations and demonstrations captivated our staff, colleagues, and attendees.

We were honoured to host the following distinguished guests - Mr. Setsuo Imazu, PhD, professor and President of Nara University, Mr. Kouji Ito, PhD, professor at the Tohoku University of Art and Design, Institute for Conservation of Cultural Property, Mr. Jun Kimura, Associate Professor, Department of Humanities, Tokai University, and Mrs Ikuno Fujii, Teikyo University, Research Institute of Cultural Properties.

During their visit, two in-person lectures were delivered: The Effectiveness of Trehalose Treatment Method on Composite Artifacts Made of Wood and Iron: Based on 20 Years of Experience Preserving Artifacts at the Takashima Underwater Ruins Site, including The Pulley of the Turkish Warship Ertuğrul presented by Professor Imazu; and Effectiveness of Trehalose Impregnation Treatment for Excavated Cultural Properties: Case Studies on Treatment Methods Including Large Wood-Iron Composite Artifact presented by Professor Ito.

Additionally, Mrs Vicki Richards, Manager of Materials Conservation at the Western Australian Shipwrecks Museum, held an online lecture titled: The Effectiveness of Introducing the Trehalose Method.

Following the lectures, practical workshops were conducted, allowing participants to engage directly with the trehalose conservation method. These hands-on sessions fostered a deeper understanding and application of the techniques discussed, further enriching the experience and knowledge shared by our distinguished guests.

During these sessions, particular emphasis was placed on an innovative conservation technique utilizing trehalose - a natural sugar renowned for its ability to stabilize and safeguard structures. Its growing use in underwater archaeological preservation stems from its remarkable effectiveness, particularly in protecting sensitive organic materials. This method facilitates controlled artifact drying while maintaining both structural and chemical integrity, ensuring the enduring preservation of invaluable cultural heritage.

What makes this method especially valuable is its suitability for composite materials – objects made from a combination of substances, such as wood and iron. Traditional methods often struggle to meet the conflicting preservation needs of such materials, whereas trehalose allows for a unified and gentle treatment that maintains the integrity of the entire artifact.

Another significant advantage of the trehalose method is its resistance to moisture and fluctuations in external temperature, ensuring greater stability and durability of treated objects under varying environmental conditions.

For more than two decades, Japanese researchers have been developing and implementing this method, with no negative effects or damage observed on treated materials. The presented findings further highlight the advantages of trehalose-based conservation, proving it to be superior to conventional techniques currently in practice.

The ICUA Zadar Conservation and Restoration Department has consistently relied on the polyethylene glycol (PEG) method, renowned for its reliability. However, it has notable limitations – it is not fully adaptable for composite materials, requires longer treatment times, and involves higher financial costs. By contrast, the trehalose method is reversible, adaptable for composite materials, faster, and more cost-effective, making it a promising alternative.

Given all these advantages, trehalose-based conservation represents an exciting and potentially transformative addition to our underwater cultural heritage protection practices. The collaboration with the Japanese colleagues has opened new perspectives, encouraged valuable knowledge exchange, and established a strong foundation for the possible implementation of this method in our future efforts.