Invented by French artist Louis-Jacques-Mande Daguerre in 1839, the daguerreotype was the first widely adopted photographic process and was swiftly adopted across the world, owing primarily to the lack of restrictions as well as European interest in documenting the monuments and people of the colonies.

Daguerre built on his work with Joseph Nicephore Niepce following the latter’s death in 1833. In 1839, he handed over the rights to the invention to the French government in exchange for lifelong pensions for himself and Niepce’s heir Isidore. Simultaneously, a patent for the process was filed in England that applied across all British colonies, which required a licence to use the process; on the other hand, the French government allowed anyone to use it, as a “gift to the world.”

In the years immediately following the public announcement of Daguerre’s invention, several improvements were made to the process, many of which were quickly standardised. The process involves coating a copper plate in silver and polishing it until it becomes highly reflective. The silver side is then exposed to iodine vapour, resulting in the formation of a thin coating of photosensitive silver iodide on the surface. In later improvements, bromine and chlorine vapour were added at this stage to enhance the plate’s photosensitivity and reduce exposure time.

In Daguerre’s original process, after the plate was exposed to the subject, it was treated with mercury vapour, allowing the image to reveal itself. Alternatively, French physicist Edmond Becquerel suggested replacing mercury vapour with red and yellow light to reveal the image; since the daguerreotype plate is primarily sensitive to ultraviolet and blue rays, the red and yellow rays do not overexpose the image. After the image was revealed, Daguerre submerged the plate in a warm solution of table salt to fix the image. Later, he began using sodium thiosulfate instead of table salt, and in 1840, physicist Armand Hippolyte Louis Fizeau demonstrated that a gold chloride solution works best for fixing the picture as well as adding strong contrast. This resulted in a mirror-image monochrome version of the subject that appeared to shift between positive and negative when viewed from different angles, due to the varying reflective properties of the silver plate and the slightly duller silver iodide. In some cases, the photograph was later pigmented by hand, usually to highlight the sitter’s jewellery.

The daguerreotype arrived in India in late 1839. The hub of photographic activity in India during the early decades of the craft was Calcutta (now Kolkata). After the daguerreotype’s arrival in the country, institutions such as the Asiatic Society made and displayed daguerreotypes, and the process was described in great detail, since the images themselves could not be printed and circulated.

Thacker, Spink & Co. was the earliest daguerreotype studio in the country and was established in Calcutta in January 1840. Soon after, a number of other studios were established, which offered photographic services and sold daguerreotype cameras. These studios were established largely by Britishers and Europeans, including John William Newland in Calcutta in 1850, William Johnson in Bombay (now Mumbai) in 1852 and WHS Crawford in Bombay in 1854. There were fewer Indian photographers, of which notable daguerreotypists included Ahmad Ali Khan and the Maharaja of Tripura, Birchandra Manikya.

For most people, daguerreotype images were their first encounters with photography. Since the images required five to ten minutes of exposure time, momentary scenes were impossible to capture, and therefore, the main subjects of daguerreotypes were buildings, landscapes and portraits.

Daguerreotypes could only be made once, on a metal sheet, and lacked the advantage of reproducibility of other technologies. Thus, it was replaced by collodion glass plate negatives in the late 1850s. However, daguerreotypes continued to be used for astronomy until the 1870s due to their reliably proportionate and precise rendering of the night sky.

Ideally, a daguerreotype should be stored in a sealed case so as to minimise contact with the air. However, few daguerreotypes survive today, partly because of the limited longevity of the original process and partly because of poor preservation conditions. In some cases, the corrosive cleaning chemicals used to repair daguerreotypes reacted with the silver sheet, creating large spots on the surface. When exposed to air, the silver layer becomes tarnished and discoloured. Distortions also occur in daguerreotypes that were not fixed with gold chloride. The constant threat of corrosion or fungus in the hot and humid weather in parts of India also made it particularly difficult to preserve daguerreotypes.