Salted Paper Formulae

Salted paper is perhaps the most basic of the historical or alternative processes, giving a color much like Vandyke Brown but with no worries about residual iron compounds, a somewhat longer tonal scale, and a very different gradation. The process combines a salt with silver nitrate to form a halide of silver (usually silver chloride), but since silver halides are insoluble in water it is necessary to make them form within the paper itself by coating first with the salt solution and then with the silver sensitizer.  The paper is dried between steps.

Sizing paper with gelatin, arrowroot, casein or cornstarch is recommended to keep the solutions from sinking beneath the surface, which causes the print to lose contrast.  Often gelatin is combined with the salt, but sometimes the paper is sized first and then salted.  The Albumen and Salted Paper Book, by James M. Reilly, states that typically the silver nitrate solution should be about 4 times as strong as the salt solution--so, if a 3% salt solution is used, a 12% silver nitrate solution is required (though none of the formulae below reflect this ratio).

Paper may be coated by immersion in the solutions, or by brush.  Since the salt is relatively cheap, I find it best to salt and size paper by immersion (which helps prevent paper curling because both sides are coated), but I generally use a brush or rod for coating the sensitizer.  If you coat the salt solution by brush, be sure to use a separate brush for salt and sensitizer.  Do not use a brush with a metal ferrule.  If you use a rod, a drop or two of 5% Tween-20 will help produce a more even coat with some papers.  Wear gloves when handling the silver nitrate solution.

Salted paper is particularly sensitive to minute impurities, so it is necessary to use clean utensils and carefully guard against contaminating solutions.  You may find it necessary to use distilled water for the initial wash.  Toning is usually accomplished before fixing, but may also be done afterward.  Gold is the traditional toner, but I find I prefer the color produced by a highly dilute solution of Kodak Rapid Selenium Toner (3 ml in 1 liter of water), used after the fix for 1 minute only--it produces a rich, chocolate brown color.

Salted paper is usually fixed in a 10% solution of hypo (100 grams of sodium thiosulfate in 1 liter of water) for 10 minutes.  Two fixes are recommended for optimal print permanence.

Salted paper requires a very high-contrast negative with a density range in the vicinity of 2.0 or higher.

Typical procedure

1. Coat paper with salt solution (usually with size added), and dry.
2. Coat paper with silver solution, and dry thoroughly in the dark.
3. Expose paper by contact printing with a negative under UV or sunlight.
4. Wash in running water for 2 minutes.  (I use distilled water with 2 minutes continuous agitation, followed by a running water wash.)
5. Tone, if desired.
6. Fix for 10 minutes.
7. Wash for at least 40 minutes.  The wash may be accelerated by the use of a wash aid such as Kodak Hypo Clearing Agent or a 20% solution of sodium sulfite.