In the 1840s photography was an area of constant experimentation. This is a brief and necessarily imprecise account of how the photographs of Hill and Adamson were created. For further details please refer to the the links on the previous page.
The calotype process
1. To make a calotype negative, a sheet of plain writing paper was treated in advance with solutions of silver nitrate and potassium iodide.
2. Just before loading in the camera, this paper was enhanced with additional solutions of silver nitrate and gallic acid.
3. After exposure, the latent image was treated again with a stronger solution of the same mixture and allowed to develop.
4. The resulting negative was ‘fixed’ with another chemical agent, most commonly sodium thiosulphate or ‘hypo’ which is still used to day.
5. For printing, the paper negative was laid over another sheet of photosensitive paper, fixed in a frame and left out in the sun so that the new (positive) image could develop.
6. The positive also had to be fixed and the fixing agent washed out.
The end result is known as a salted paper print and is characterised by the fibrous texture of the paper on which it was made.