Materials:
Gelatine (fish glue)
Ammonium Chloride
Sodium Citrate
Silver Nitrate
Sodium Thiosulphate (Hyposulphite)
Sodium Sulphite, anhydrous
Distilled water (at least for the solution "b", as indicated later)


This is a someway "classic" formula, also reported in many O.T. manuals, and is only lightly different from the original Talbot formula (which was using only sodium chloride).

Prepare the following solutions:

Solution A
Gelatine	10	g
Ammonium Chloride	10	g
Sodium Citrate	10	g
Water to make	1000	ml
Solution B
Silver nitrate	13	g
Water to make	100	ml
Fixer
Sodium Thiosulphate	100	g
Sodium Sulphite an.	10	g
Water to make	1000	ml

Solution A: soak the gelatin in 500 ml cold water for half an hour. Then warm the water to 50°C and let the gelatine dissolve completely. Then add the ammonium chloride and the sodium citrate previously dissolved in little water. Let the mix cool down to room temperature and bring the volume to 1000 ml with cold water.
Solution B: dissolve the silver nitrate in 60 ml of warm water and then bring the volume to 100 ml with cold water. Only distilled or deionized water should be used for this solution.
Fixer: dissolve the sodium thiosulphate in 500 ml warm water, the add the sulphite. When dissolved bring the volume to 1000 ml with cold water.

Warnings:

Silver nitrate stains skin, paper, wood, or whichever porous or absorbent material it comes in contact with. The stains show up some time after contact, even if it has occurred with diluted solutions and the zone has been washed.
In case of skin contact immediately wash with running water, then rub with some fresh fixer and wash again, then ... hope for the silver not to be penetrated into the skin so it will not form, after a day, some ugly -but not dangerous- black stains which, unfortunately, will be removed only by natural skin "peeling".
In case of contact with the eyes wash thoroughly and contact a physician.

Keep the B solution in a dark cool place.

Paper preparation (Salting):
NOTE: Paper has to be previously sized (see the appropriate section on paper treatment and sizing).

Immerse the sheet of paper in the A solution, which will have been previously warmed to 45°C, and let it rest for ten minutes. Some agitation is necessary as well as removing eventual air bubbles from the paper's surface. Take the sheet out the tray letting it slide on the tray border to eliminate most of the solution from the back of the paper. Let it dry on a flat horizontal surface till the gelatin will be solidified and only then hang it to dry.

Paper which has been given the above preparation is stable in time.


Sensitization:
Using a pencil mark the area of the negative you are about to print. In subdued light or under a small light bulb, coat the marked area with the B Solution using either a brush or a glass rod. Make sure the coating is even, without pooling and avoiding too much pressure not to damage the gelatin layer.
Let the sheet of paper dry flat in the darkness.

Exposure and development:
The sensitized paper must be used as soon as possible.
As soon as the exposure begins, UV light will form a brown image on the paper. The degree of contrast can be followed by inspection, lifting a corner of the paper while avoiding to remove the registration between paper and negative. Using a back-split printing frame makes this much easier to handle.
Allow the paper darken a little more than you judge as optimum, as the fixer will decrease the density of the print.

Fixing and washing:
Take the paper out the frame, immerse it in a tray full of tap water at room temperature and agitate immediately. The water will turn milky and opaque, because of the dissolving of the unexposed silver nitrate and its precipitation with chlorides in the water. Change the water for some times until clear.
Once washed in water, transfer the paper in a tray with the fixing solution and agitate. Ten minutes after take the paper out the tray and wash for at least half an hour, just like conventional b/w papers.
At the end hang and let it dry.



Notes:

The salted paper is self-masking, as the formed image masks the layer beneath it. As a consequence, the contrast becomes lower as the darkening proceeds, and this fact must be taken into account when preparing the negative.

The salted paper may fade with time, because of the very small silver particles making the image.
If you look for the maximum image stability, it is necessary to tone it in a gold bath.

Bolognesi G.P. (1994) "Antiche Tecniche" - Collana Manuali di Fotografia di Tutti Fotografi - Ed. Progresso, Milano 1994

Barnier J. (2000) "Coming into Focus". Chronicle Books, S. Francisco