calotípia

Calotípia, also known as the talbotype process, is an early photographic technique invented by William Henry Fox Talbot in 1841. It was one of the first photographic processes to produce a negative image on paper, which could then be used to create multiple positive prints. This made it a significant advancement over earlier methods like the daguerreotype, which produced a unique positive image on a metal plate.

The calotype process involved coating paper with iodide of silver, then sensitizing it with a solution of gallic acid and silver nitrate. The paper was exposed in a camera, developing the latent image with more gallic acid. Finally, the image was fixed with a solution of sodium thiosulfate. The resulting paper negative was then contact-printed onto another sheet of sensitized paper to produce a positive image.

While the calotype produced softer, less detailed images compared to the daguerreotype due to the paper's grain, its ability to create multiple prints was a major advantage. This laid the groundwork for modern photographic printing. Talbot's invention was crucial in the development of photography, allowing for the reproduction and dissemination of images in a way that was previously impossible. The process was widely used in the mid-19th century before being superseded by wet collodion processes.