Kalotypia

Kalotypia, also known as calotype, is an early photographic process developed by Henry Fox Talbot in the 1840s. It uses paper coated with silver iodide to create a latent image when exposed in a camera. After development and fixing, a permanent negative is produced, which can be used to make multiple positive prints by contact printing. This capability of reproducible imagery marked a major shift from the single, non-reproducible images of earlier methods.

The term kalotypia derives from Greek roots meaning “beautiful impression.” The process was among the first practical negative–positive photographic methods, enabling photographers to produce more than one copy of a scene.

Process overview: paper is sensitized with silver salts (silver nitrate and iodide) to form silver iodide on the surface. After drying, the sheet is exposed in the camera, creating a latent image. The image is developed chemically (commonly with gallic or pyrogallol compounds and silver nitrate) to form a metallic silver negative, which is then fixed with a solution such as sodium thiosulfate. The negative is used to produce positive prints by placing it in contact with sensitized paper and exposing to light.

Historical significance and limitations: calotypes offered true photographic negatives and the ability to produce multiple prints, influencing 19th-century photography and expanding reproducibility. However, they tended to be less sharp than daguerreotypes, with a soft tonal range and grainy texture due to the paper base and diffusion of the image. Sensitivity was relatively low and exposure times were long, contributing to their gradual decline in favor of later processes such as albumen prints and gelatin emulsions. Despite their decline, calotypes laid important groundwork for modern photographic reproduction.