Calotype (Greek: kalos – “beautiful”, and tupos – “impression”), sometimes called Talbotype, by its inventor William Henry Fox Talbot’s Calotype process revolutionized the realm of photography by allowing for the generation of numerous copies from a single negative. This nineteenth-century innovation made multiple prints available and heralded an age where photographs could be widely preserved, replicated, and enjoyed.
The Calotype process involved coating a piece of paper with a mixture of silver iodide and potassium iodide. The paper was then exposed to light in a camera, creating a negative image. The paper was then washed in a solution of gallic acid, which hardened the silver particles and made them resistant to further development. The paper was then rewashed in a sodium thiosulfate solution, which removed the remaining unexposed silver iodide. This process left behind a negative image on the paper.
Early photographers could create multiple prints of the same picture using a negative image and light. Through contact printing, they’d place their negatives onto sensitized paper before exposing it to natural light to transform them into beautiful positives – allowing whole collections of photographs with each print boasting its unique quality.
The calotype process is considered the first practical negative-positive process. It was widely used during the 1840s and 1850s but was eventually replaced by the more advanced collodion process. Despite this, the Calotype process significantly impacted the development of photography, as it opened the door for the creation of multiple copies of a single image and laid the foundation for the modern photographic industry.
The Calotype process is an important milestone in the history of photography. It was one of the first photographic processes to produce a negative image, which could then be used to make multiple prints. It was widely used during the 1840s and 1850s but was eventually replaced by the more advanced collodion process. The Calotype process opened the door for creating multiple copies of a single image and laid the foundation for the modern photographic industry.