Unblinking Eye
                             Salted Paper Formulae

 

by Ed Buffaloe

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, and a longer tonal scale.  The process combines a salt and silver nitrate to form silver halide (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, starch, albumen, or even casein is recommended to keep the salt and silver solution from sinking beneath the surface--which causes the print to lose contrast.  Often the size 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.

 

Paper may be coated by immersion in the solutions, or by brush.  Since the salt is relatively cheap, I find it easy to size and salt paper by immersion (which helps prevent paper curling), 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. 

Salted paper is particularly sensitive to minute impurities at every step of the process, so it is necessary to use clean utensils and carefully guard against contaminating solutions.  I have found it necessary to wash the print in distilled water for two minutes immediately after exposure and before placing it in the wash tray for further washing--it seems to prevent indiscriminate staining.  Likewise, I find it necessary to replace the brush used for the silver nitrate solution fairly regularly.

Paper can be problematic--some papers seem to stain more than others.  I have found Fabriano Uno to be a good paper for the salt process, though I’m sure there are many others.  I had many difficulties with Arches, but a friend achieved good results with a different batch of the same paper.

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 in excess of 2.0.  I have a negative with a maximum density of 3.3 that prints quite well on salted paper.

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, as 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.

from The Photo Miniature #69

Salt Solution

Sodium chloride

60 grains

Citric acid

120 grains

Distilled water

7 ounces

Soft gelatine

1/2 ounce

Sensitizer

Silver nitrate

150 grains

Distilled water

4 ounces

The salt and acid are first dissolved in the water, and then the gelatine is added, and the whole stirred and gradually heated up to about 40C (105 F) until complete solution has taken place.  The solution must be strained or filtered through two thicknesses of muslin to free it from small insoluble particles of gelatine.

from Coming into Focus

Salt Solution

Ammonium chloride

10 grams

Potassium citrate

10 grams

Distilled water to make

500 ml

Sensitizer

Silver nitrate

12 grams

Distilled water to make

100 ml

from Historic Photographic Processes

Salt Solution

Water

250 ml

Gelatine

2 grams

Sodium citrate

5 grams

Ammonium chloride

5 grams

Sensitizer

Distilled water

90 ml

Silver nitrate

12 grams

Distilled water to make

100 ml

If arrowroot-sized paper is used, the sensitizer should contain 4-5% citric acid.

from Encyclopedia of Photography

Salt Solution

Gelatine

100 grains

Chrome alum

4 grains

Ammonium chloride

50 grains

Water to make

10 ounces

Sensitizer

Silver nitrate

600 grains

Citric acid

300 grains

Distilled water to make

10 ounces

Soak gelatine 30 minutes in 8 ounces of cold water, and dissolve the chrome alum in 2 ounces.  Heat the gelatine mixture in a water bath and stir in the ammonium chloride.  Strain the gelatine solution through fine muslin and gradually add the chrome alum solution.  Store in hot water to keep the solution fluid for coating.  Sponge the salt solution on as quickly and evenly as possible, and go over with a squeezed sponge to remove excess solution.

Namias’ Formula

Salt Solution

Gelatin

25 grams

Citric acid

5 grams

Ammonia

6 ml

Zinc chloride crystals

6 grams

Water

1 liter

Soak the gelatin in half the water and dissolve with heat up to about 105 F (40C ); dissolve the acid in the remainder of the water, add the ammonia, then the chloride.  Mix the two solutions and filter.  Tartaric acid may be substituted for citric to obtain darker brown tones.

Sensitizer

Silver nitrate

12 grams

Citric acid

5 grams

Glycerin

5 ml

Water

100 ml

Greater contrast may be obtained by adding small amounts of a 5% solution of potassium bichromate.

Avoirdupois to Metric Weight Conversions

Ounces

Grains

Grams

0.03527

15.43

1

16

7000

453.6

1

437.5

28.35

 

1

0.0648

U.S. Liquid to Metric Measure

Ounces

Drams

Milliliters

1

8

29.57

0.125

1 (60 minims)

3.697

0.03381

0.2705

1

from Spirits of Salts

Salt Solution

Sodium chloride (or ammonium)

20 grams

Cold tap water

1 liter

Sensitizer

Solution 1

 

Distilled water

50 ml

Silver nitrate

12 grams

Solution 2

 

Distilled water

50 ml

Citric acid

6 grams

Combine solutions 1 and 2.

Salt Solution with Gelatin

Sodium chloride

6 grams

Gelatin

2 grams

Water to make

300 ml

Place gelatine in 100 ml water and let soak for 15 minutes.  Add 200 ml water at 45 C and stir until dissolved.  Then add the salt.

from The Keepers of Light

Gelatin/Salt Solution

Water

280 ml

Gelatin

2 grams

Sodium citrate

6 grams

Ammonium chloride

6 grams

Soak gelatin in 100 ml room temperature water for 10 minutes, then add 180 ml water at 43 C (100 F) and dissolve rest of chemicals.

Starch/Salt Solution

Water

280 ml

Argo cornstarch

5 grams

Sodium citrate

6 grams

Ammonium chloride

6 grams

Dissolve starch in 80 ml room temperature water, then add 200 ml boiling water.  Boil 3 minutes and remove from heat.  Add the other chemicals while stirring.

Sensitizer

Distilled water at 38 C (100 F)

30 ml

Silver nitrate

4 grams

from Photographic Facts and Formulas

Arrowroot/Salt Solution

Arrowroot

20 grams

Water

750 ml

Rub the arrowroot into a cream with a small amount of water.  Boil the remainder of the water and add the arrowroot cream slowly with constant stirring.  Stir until a translucent liquid is formed.  The quantity of arrowroot may be increased to 30 grams for better surface brilliance.  Then add:

Ammonium chloride

14 grams

Sodium carbonate (crystals)

23 grams

Citric acid

7 grams

Water

250 ml

Boil the salt solution for 5 minutes to eliminate carbon dioxide and add very slowly to the arrowroot liquid with constant stirring.  Use a container twice the size of the solution you are mixing so it does not boil over.  Strain the solution through fine muslin while hot.  Immerse paper in solution for 2 minutes, hang until almost dry, then immerse for an additional 2 minutes and hang by the opposite corner.  Sensitize with a 12% solution of silver nitrate.

Gelatin/Salt Solution

Gelatin

4.5 grams

Ammonium chloride

18 grams

Sodium citrate

21.5 grams

Salt

7 grams

Water

1 liter

Sensitizer

Silver nitrate

73 grams

Citric acid

52 grams

Water

500 ml

Caseine Formula
from Photographic Facts & Formulas

Salt Solution

Ammonium chloride

4 grams

Sodium citrate

40 grams

Water to make

500 ml

Casein Solution

Casein

40 grams

Ammonia

50 ml

Water to make

500 ml

You can also make the casein solution from 40 grams of washed low fat cottage cheese curds, with the same amount of ammonia and water.  Either way you make the casein, you must warm it until the curds dissolve.  Mix the salt and casein solutions separately, then combine them while stirring continuously.  Use a container twice the size of the solution you are mixing so it does not boil over.  Strain the combined solution through a layer of muslin and immerse paper for two minutes.  Hang to dry.  The solution will only keep for a day or two, so size all the paper you will need ASAP.

Sensitizer

Silver nitrate 12% solution

As necessary

This was originally a single-solution wherein 70 grams of silver nitrate was added, but in my experience adding silver nitrate to the salt and casein causes a white precipitate to form, which then has to be strained out.  It does work as a single solution, but I find two solutions works better.

References

  • John Barnier, editor.  Coming into Focus:  A Step-by-Step Guide to Alternative Photographic Printing Processes.  San Francisco:  Chronicle Books, 2000.
  • William Crawford.  The Keepers of Light: A History and Working Guide to Early Photographic Processes.  Dobbs Ferry, New York:  Morgan & Morgan, 1979.
  • Richard Farber.  Historic Photographic Processes:  A Guide to Creating Handmade Photographic Images.  New York:  Allworth Press, 1998.
  • Bernard E. Jones.  Encyclopedia of Photography.  New York:  Arno Press, 1974.
  • Randall Webb & Martin Reed.  Spirits of Salts:  A Working Guide to Old Photographic Processes.  London:  Argentum, 1999.
  • John Tennant.  The Photo Miniature, Vol. II, No. 22.  London:  Dawbarn & Ward, January 1901.
  • E. J. Wall, Franklin I. Jordan, and John S. Carroll.  Photographic Facts and Formulas.  Garden City, New York:  Amphoto, 1976.
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