The salt print was the dominant paper-basedphotographic process for producingpositive prints (fromnegatives) from 1839 until approximately 1860.
The salted paper technique was created in the mid-1830s by English scientist and inventorHenry 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 ofsilver nitrate. This produced a tenacious coating ofsilver 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 astrong solution of salt, which altered the chemical balance and made the paper only slightly sensitive to additional exposure. In 1839, washing with a solution ofsodium thiosulfate ("hypo") was found to be the most effective way to make the results trulylight-fast.
The salt print process is often confused with Talbot's slightly later 1841calotype or "talbotype" process, in part because salt printing was mostly used for making prints from calotype paper negatives rather than live subjects. Calotype paper employedsilver iodide instead of silver chloride. Calotype was adeveloping out process, not aprinting out process like the salt print. The most important functional difference is that it allowed a much shorter exposure to produce an invisiblelatent image which was thenchemically developed to visibility. This made calotype paper far more practical for use in acamera. Salted paper typically required at least an hour of exposure in the camera to yield a negative showing much more than objectssilhouetted against the sky. Gold toning of the salted paper print was a popular technique to make it much more permanent.[1][2]
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].
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