Salt print
Photographic process
From Wikipedia, the free encyclopedia
The salt print was the dominant paper-based photographic process for producing positive prints (from negatives) from 1839 until approximately 1860.
The salted paper technique was created in the mid-1830s by English scientist and inventor Henry Fox Talbot. He made what he called "sensitive paper" for "photogenic drawing" by wetting a sheet of writing paper with a weak solution of ordinary table salt (sodium chloride), blotting and drying it, then brushing one side with a strong solution of silver nitrate. This produced a tenacious coating of silver chloride in an especially light-sensitive chemical condition. The paper darkened where it was exposed to light. When the darkening was judged to be sufficient, the exposure was ended 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. 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.
Steps to create salt print
- Mix and prepare salt solution and silver nitrate solution in two separate bottles
- Apply salt solution to paper and dry
- Apply silver nitrate solution to paper and dry
- Place negative (or object for photogram) over sensitised paper and expose to UV light
- Wash in water (10-20 minutes)
- Wash in salt water (30 seconds-1 minute)
- Second wash in water (approx 10 mins)
- Tone (usually in gold chloride solution)
- Wash in water (10 minutes)
- Fix in sodium thiosulfate bath 1 (4 minutes)
- Fix in sodium thisosulfate bath 2 (4 minutes)
- Wash in water (4 minutes)
- Remove fixer with hypoclear of sodium sulphite (4 minutes)
- Wash in clean water for 30 minutes - 1 hour.
The salt print process is often confused with Talbot's slightly later 1841 calotype or "talbotype" process, in part because salt printing was mostly used for making prints from calotype paper negatives rather than live subjects. Calotype paper employed silver iodide instead of silver chloride. Calotype was a developing out process, not a printing out process like the salt print. The most important functional difference is that it allowed a much shorter exposure to produce an invisible latent image which was then chemically developed to visibility. This made calotype paper far more practical for use in a camera. Salted paper typically required at least an hour of exposure in the camera to yield a negative showing much more than objects silhouetted against the sky. Gold toning of the salted paper print was a popular technique to make it much more permanent.[1][2]
Contemporary uses of the salt print
In the 21st century, salt prints remain a niche method in the art photography world.[3] However, a growing number of contemporary artists and photographers are using the salt print methods in their work.[4]
Since the advances of digital negatives, it is now possible to create salt prints using digital photos which can be manipulated in digital darkroom softwares such as Photoshop to create highly suitable negatives for the salt process.
Different emulsions are now used including sodium chloride or ammonium chloride mixed with binding agents such as gelatine and arrowroot for varying resulting qualities.[5] Many of the issues with preserving salt prints in the past have been resolved through research over many decades. Salt prints that have been processed and stored correctly can last for many generations.[6]
Ellie Young of Gold Street Studios in Australia is considered as one of the few contemporary masters of the salt process working today.[5]
