Prof. Ha Dinh Duc, a turtle expert.

The staff of the museum is completing the final steps of a two-year preservation process of the Hoan Kiem Lake. 

The Hoan Kiem turtle died in January 2016 and was handed over to the museum for preservation. It was 185 cm long, with the shell of 100 cm wide, weighing 169 kilogram.

The cause of death was aging. The Hoan Kiem turtle is estimated at 200 years old.

Trung Minh, the head of the museum, received the turtle from the Hanoi Science & Technology Department and kept it in a room at minus 15 degrees Celsius.

After an urgent meeting about the preservation method, the Hanoi People’s Committee decided to apply plastination technology, advanced technology that keeps the  complexion of the specimen and protects soft tissues. 

“The contract signed between the local authorities and the museum sets a strict requirement that all the skin, bone and cartilage of the turtle must be preserved intact,” said Phan Ke Long, deputy director of the museum.

Plastination is a unique technique of tissue preservation developed by a German scientist in 1978. The plastination process includes four phases 1) fixation 2) removal of water and lipids 3) forced impregnation and 4) hardening. Water and lipids are replaced by special polymers.

In the first phase, the turtle was soaked in formaldehyde or other preservation solutions to help prevent tissue decomposition. 

In the second step, after the dissection, the specimen was placed in an acetone tank. Under freezing conditions, acetone draws out all water and replaces the space inside of the cells.

In the third phase, the specimen was put into a liquid polymer tank, such as silicon rubber, polyester or epoxy resin. By creating a vacuum environment, acetone is boiled at a low temperature. As the acetone evaporates, empty cells penetrate liquid polymer, becoming cells filled with liquid.

Finally, polymer will be hardened with treatment in gas, heat or ultraviolet light.

Long said plastination is the right choice for the Hoan Kiem turtle because plastinates are dry, odorless, and durable enough for the broader public.

Also according to Long, the resin used for preservation is German made. The museum invited two German leading preservation specialists to help preserve the Hoan Kiem turtle. The specialists flew to Vietnam five times over the last two years.

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Thanh Mai