William Fox Talbot invented the salted paper process; to do this he first tried using paper coated with a silver nitrate solution, this paper was then exposed to light which gave a faint metallic silver image. He realised that by first applying salt to the paper and then coating it with the silver nitrate solution, it gave a much stronger image. This old process uses the combination of salt coated paper and silver nitrate solution, then exposed in sunlight these prints are created.
Soak the sheet of paper in a solution of salt (1 litre of cold water mixed with 20 grams of sodium chloride), followed by coating one side only with a mix of silver nitrate (12 grams) and distilled water (50ml), do all this in the darkroom. After the coated paper is dry, place sensitive side up, directly under a negative and beneath a sheet of glass within a printing frame. Expose the paper, coated side up, with the negative and glass placed on top, the correct exposure will depend on the density of the negative.
After exposure, when developing the prints, for the fixing Bath mix 500ml cold water with 25 grams of sodium thiosulphate powder plus 2 grams of bicarbonate of soda. To fix the print leave it in the solution for about 5 minutes, the print then has to be washed for thirty minutes in running water and then dried.
For salt prints you can print negative versions of digital photographs onto acetate and then place them onto the paper. To do this, you have to use Photoshop to open your image and change it to greyscale, which discards the colour information in the image. Then you have to invert the colour. Also it’s best to change the image size to the size you will print it and have the resolution at 300 dpi.
Here are some examples of salt printing:
The overall effect of salt printing gives a warm brown colour to your prints, these tones can vary slightly depending on the negative and chemicals. The images are of a good standard and are clear, not much detail is lost through this method and so it is a good alternative process that could be adopted if you are wanting to print digital photographs (printed onto acetate) in a clear and beautiful way. I think because of the colour and tones of the images, they look a lot older than normal colour photography and even black and white, this will mean that your photographs will look dated and this could be a good effect if wanted for a project.