In the beginning - photographic processes

Henry Fox Talbot

Henry Fox Talbot ( 11th February 1800- 17th September 1877) was a British scientist, inventor and photography pioneer.


Talbot was known for creating reasonably light, fast and permanent photographs. He done this through paper-based photographic processes called the salted paper process and the calotype process.


Salted Paper example

Articles of glass; salted paper print from paper negative; before June 1844.

Calotype Example


Examples images of the calotype process.
Camera used for the calotype process
Paper-based photographic process for Salted paper

Salted paper process was the dominant paper-based photographic process which is also known as the "printing out" process. It is used when writing paper is bathed in a weak solution of ordinary table salt (sodium chloride), dried, then brushed on one side with a strong solution of silver nitrate and left to dry. You would then place your negative on top of the writing paper (ink-side down) and place into a framed glass; the framed glass would then be put under a bright light source such as sunlight. The paper would then darken when exposed to light; when the darkening was sufficient the exposure was ended. The paper would then be took out of the glass frame and the result was stabilized by applying a strong solution of salt which altered the chemical balance and made the paper only slightly sensitive to additional exposure. This would then be washed and left to dry. In 1839, washing with a solution of sodium thiosulfate ("hypo") was found to be the most effective way to make the results truly light-fast.

Calotype process is an improvement of Talbots earlier photographic technique of Salted paper, known as the "developing out process". The base of a calotype negative was high quality writing paper. The first stage, conducted in candlelight, was to prepare the paper. The paper was washed over with a solution of silver nitrate and dried by gentle heat. When nearly dry, it was soaked in a solution of potassium iodide for two or three minutes, rinsed and again dried. As long as this iodized paper was stored carefully, it could be kept for some time, so it was generally prepared in batches ahead of time. Immediately before taking a photograph, a fresh solution of gallo-nitrate of silver was mixed up. This was made from equal quantities of a solution of silver nitrate and one of gallic acid. Under weak candlelight, a sheet of iodized paper was coated with this solution, left to sit for about thirty seconds and then dipped in water. It was then partially dried in the dark, often using blotting paper. The calotype paper could be employed completely dry, but was more sensitive when moist, and in any case had to be exposed in the camera within a few hours of preparation.

Under near-total darkness, the sensitive calotype paper was loaded in the camera. It was exposed to the scene, sometimes for as little as ten seconds, usually for a time closer to a minute, and sometimes for tens of minutes. If you had to look at the sheet of paper after withdrawing it from the camera, no image would be seen. An invisible latent image was formed by the action of light. A fresh solution of gallo-nitrate of silver was used. Washed over the sheet of paper in a darkened room, it developed a visible image, usually within a few seconds. When it had developed the paper was then washed over with a fixing liquid. This was sometimes a solution of potassium bromide and sometimes a solution of hypo. Washing and drying completed the process. This resulted in an negative of deep brown or black in colour.


How to emulate this digitally: You could emulate this technique digitally by using the software Photoshop and adding grain, sepia tones and vintage filters to the image. When replicating the Salt printing process you could add a softening filter. blur the image and add borders.

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