Print images onto ordinary paper turned light-sensitive by some almost magical alchemy from the earliest days of photographic history. Salt your paper with ordinary table-salt and sensitize it with silver-nitrate. Contact print large negatives in the sunlight and see the images appear right before your eyes. No darkroom needed.
Salt printing is one of the earliest photographic processes in history. It was invented by an Englishman named William Henry Fox Talbot in the early 1830s and was once the go-to method for printing negatives. Talbot knew that silver-chloride could be used for photographic printing but it couldn’t be coated onto paper. In a stroke of genius he first applied ordinary salt-water and in a second step sensitized the paper with silver-nitrate. The two chemicals combine to form silver-chloride in the paper. Voilà: photographic paper made at home!
- water (both tap water and a bit of demineralised/distilled water)
- acid free fine-art paper that can stand being immersed in water for half an hour
- silver nitrate (ask a pharmacist or order online – it’s expensive but you’ll only need 10g which will last for a long time)
- sodium-thiosulfate as a fixer (buy from online photo-supply stores)
- some citric acid (available at big supermarkets as a descaler for coffee-makers)
- a printable large-format negative
- a picture frame
What? You don’t have a large format camera? No problem, you can just use a paper negative or (even better) print your digital negatives onto overhead projector transparencies.
1. Mix a 2 percent salt solution (e.g. 20g of sea salt for 1 litre of water) and fill it into a shallow tray. Float a sheet of paper on the surface like this:
2. When the edges of the paper curl upwards, grab one corner and slowly peel the paper away from the water’s surface. Hang or lay flat to let completely dry.
3. Mix a solution of 10g of silver-nitrate in 42ml of demineralised water and another one of 5g of citric acid in 42ml of demineralised water. Combind the two solutions and store them in a brown bottle. Careful, the solution needs to be kept in the dark or in very low light and also it STAINS ABOUT EVERYTHING IT GETS IN TOUCH WITH!
In dim light, evenly brush the salted side of your paper with the silver-nitrate solution. Let the paper dry in the dark.
4. Lay your sensitised paper in a picture frame, put the negative on top and keep it in place with the frame’s glass pane. Expose the paper in the sunlight until the light parts are dark purple or almost black.
5. Bring into a dimly lit room, remove from frame, wash in a tray with cool water until the runoff water runs clear. Fix in a sodium-thiosulfate solution (50g to the litre) for 10 to 15 minutes. Wash again and hang to dry.
The final print will look a lot darker than the wet paper. Also, the image is really embedded “in” the paper and looks rather cool.
For a far more detailed description and also a German version please visit my blog