Salt Printing is one of the earliest forms of image capture and even predates the Cyanotype. Invented by Henry Fox Talbot in involves the mixing of two chemical solutions to create a light-sensitive liquid which can then be used to create a photograph.
In order to complete this for my self I needed the following items
Sodium Chloride (Salt)
Bicarbonate of Soda
Simple brown glass bottle
To start with I mixed 20g of Salt with 1 litre of water and soaked the paper in this until it was fully saturated. It is important to use sea salt or sodium chloride crystals purchased from a chemistry supplier as standard table salt will not work.
Either leave your salt solution to dry or use a hair dryer. The paper at this stage is only sensitive to UV light so a normal light bulb will not for the paper meaning at this stage you are able to work under normal lighting.
The next procedure requires two separate mixtures and it is important that these be made independent of each other before mixing and should be completed under a safe light.
First mix 12g of Silver Nitrate with 50ml of water and then mix 6g of citric acid with 50 ml of distilled water. Once these two have been prepared they should be stored in a dark brown glass bottle. Once you have your solution using a brush then carefully paint it onto the dry salt paper. Allow this to dry and you are ready to expose it to UV light. I used a medium format negative, placed this onto the salt paper before trapping the items under glass and placing them in direct sunlight. Once exposed the paper begins to turn dark brown, the process took around 10-15mins altogether and once complete we returned to the dark room.
With the paper exposed we placed it into the fix solution for 5 mins to prevent further developing, although a standard fix can be used at a ration of 1 parts to 19 it has the potential to damage your print so alternatively mix 25g of Sodium Thiosulphate powder with 500ml of water and 2g of bicarbonate soda.
Once I had soaked the print in the fix for 5 mins I transferred it into a standard wash bath for 10 mins to ensure that all chemicals had been removed.
My final result is below.
The image has come out rather more clearly than I expected and is better quality than I managed to achieve with the Cyanotype process. The Salt printing system is more complicated though, requires more chemicals and although not hazardous can leave permanent dark stains on clothing.
Having now tried both systems I can see why people found them very popular in the mid 19th century however, here in the 21st century I was not so excited. I understand that people still enjoy working this way and it is fascinating to see it work. There are many artistic applications to using these methods but they are not something I have any plans to use in the future.