The images of botanical and geological specimens from the garden of Claude Monet, founder of French Impressionism, are part of an exhibition by artist Pipo Nguyen Duy in Hanoi.

Entitled Another Expedition, the exhibition brings together 600 cyanotype prints made by Duy when he was an artist-in-residence at Monet's garden.

He researched the cyanotype technique, the monochrome photographic printing process that gave a cyan-blue print, which was developed by William Henry Fox Talbot (1800-77) and Sir John Herschel (1792-1871).

In 1842, Herschel discovered that ferric (iron) salts could be reduced to a ferrous state by light and then combined with other salts to create a blue-and-white image.

Cyanotype is a contact print process that requires a negative film of the same size as the size of the print you want. A cyanotype with a blue image on a white background is obtained using a negative transparency. In order to obtain a pale white image on a blue background, a positive transparency must be used.

Duy patiently collects botanical specimens. He makes the photo sensitive solution of a sensitiser and soaks the sensitiser into cotton-based watercolour paper. He also creates a negative image on a transparency with a laser printer, placing the negative over the dried, sensitised paper.

"Then the image is exposed to sunlight at different times of the day to create different shades of colours," he said, adding that he finally washes the image in water to develop."

Born in Hue, Duy immigrated to the United States in 1975. He earned a degree in Master of Arts in Photography and a Master of Fine Arts in Photography from the University of New Mexico at Albuquerque. He is now Professor of Art at Oberlin College, Ohio.

The exhibition will run until July 19 at L'Espace, 24 Trang Tien street, Hanoi.-VNA