Historical Context
Salt printing was the first paper-based photographic process, invented by William Henry Fox Talbot in 1833-34. It was the dominant positive printing process from 1839 until approximately 1860, when it was superseded by albumen printing.
Chemistry
Salt Bath (for sizing paper)
| Component | Amount |
|---|---|
| Sodium chloride (table salt) | 20-30 g |
| Gelatin (optional sizing agent) | 5-10 g |
| Water | 1 litre |
Silver Bath (sensitiser)
| Component | Amount |
|---|---|
| Silver nitrate | 100-120 g |
| Distilled water | 1 litre |
| Citric acid (optional preservative) | 5 g |
Alternative Two-Step Method
Some practitioners prefer separate sizing and sensitising steps:
Step 1 — Salt solution:
| Component | Amount |
|---|---|
| Ammonium chloride or sodium chloride | 20 g |
| Distilled water | 1 litre |
Step 2 — Silver solution:
| Component | Amount |
|---|---|
| Silver nitrate | 120 g |
| Distilled water | 1 litre |
Procedure
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Paper preparation: Select smooth, hot-pressed paper. Paper can be sized with gelatin or used unsized for softer results.
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Salting: Float or brush paper in salt solution. Allow to dry thoroughly.
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Sensitising: Under subdued light, float or brush salted paper in silver nitrate solution. Dry in darkness.
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Exposure: Contact print under UV light (sunlight is traditional). This is a printing-out process—expose until shadows are distinctly darker than desired (exposure will reduce in fixing).
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Salt bath (optional): Brief immersion in weak salt solution can help set the image.
-
Fixing: Fix in weak sodium thiosulfate:
Component Amount Sodium thiosulfate 50-100 g Water 1 litre Fix for 5-10 minutes.
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Washing: Thorough washing for 30+ minutes.
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Toning (recommended): Gold toning dramatically improves permanence and can shift colour.
Gold Toning for Salt Prints
Alkaline gold toner (produces purple-brown tones):
| Component | Amount |
|---|---|
| Distilled water | 1 litre |
| Sodium carbonate | 5 g |
| Gold chloride (1% solution) | 10 ml |
Tone for 5-15 minutes until colour shift plateaus. Untoned salt prints fade significantly; gold toning is highly recommended for permanence.
Paper Selection
Salt printing works best on smooth, well-sized papers:
- Hot-pressed watercolour papers
- Crane's Platinotype
- Arches Platine
- Weston Diploma Parchment
The paper surface significantly affects the final appearance—smoother papers produce finer detail, while rougher papers create a softer, more atmospheric look.
Troubleshooting
| Problem | Likely Cause | Solution |
|---|---|---|
| Weak image | Under-salting; weak silver bath | Increase salt/silver concentration |
| Mottled appearance | Uneven salting or sensitising | Improve floating/brushing technique |
| Fading | Insufficient fixing; no toning | Fix longer; tone with gold |
| Staining | Contaminated chemicals; insufficient washing | Use fresh solutions; extend washing |
Safety
| Chemical | Hazard | Precautions |
|---|---|---|
| Silver nitrate | Corrosive; stains skin permanently | Gloves essential |
| Sodium thiosulfate | Low toxicity | Standard precautions |
| Gold chloride | Toxic if ingested | Gloves; careful handling |
Further Reading
Christina Z. Anderson, Salted Paper Printing: A Step-by-Step Manual Highlighting Contemporary Artists (Routledge, 2017) Part of the Contemporary Practices series. Covers photogenic drawing through advanced methods, animal-friendly alternatives, toning, and combination printing. The definitive modern reference for salt printing.
Christopher James, The Book of Alternative Photographic Processes, 3rd Edition (Cengage Learning, 2015) The definitive comprehensive text on alternative processes, with detailed coverage of salt printing including historical context and practical guidance.
Jill Enfield, Jill Enfield's Guide to Photographic Alternative Processes, 2nd Edition (Routledge, 2020) Covers historical roots through digital manipulation, with practical salt printing instruction.