Collodion process
Collodion process, early photographic technique invented by Englishman Frederick Scott Archer in 1850. The process involved adding a soluble iodide to a solution of collodion and coating a glass plate with the mixture. In the darkroom the plate was immersed in a solution of silver nitrate to form silver iodide . The plate, still wet, was exposed in the camera. It was then developed by pouring a solution of pyrogallic acid over it and was fixed with a strong solution of sodium thiosulfate, for which potassium cyanide was later substituted. Immediate developing and fixing were necessary because, after the collodion film had dried, it became waterproof and the reagent solutions could not penetrate it. The process was valued for the level of detail and clarity it allowed. A modification of the process, in which an underexposed negative was backed with black paper or velvet to form what was called an Ambrotype, became very popular from the mid- to late 19th century, as did a version on black lacquered metal known as a tintype , or ferrotype.
PREPARATION POE BOY COLLODION
To make about 300ml of photographic collodion:
Add 150ml ethyl alcohol 96° to 120ml collodion USP 5%.
To prepare the saline solution, dissolve 1,5gr of potassium bromide ( Kbr) into 3ml demineralized H2O, then add 2,5gr potassium iodide ( KI). Use the 25ml beaker .
It is difficult to dissolve the iodine salt, we suggest you heat up the water solution in a bain-marie (double bath) at maximum temperature of 50°C. Keep stirring until fully dissolved. You might have to add a little extra water, drop by drop, but do not exceed a total of 4ml of saline solution.
If you do not heat it, the iodine salt will precipitate because the solution is supersaturated, therefore when you add it to the diluted collodion it should always be warm, around 50oC.
Pour the saline solution into the collodion while stirring rapidly, you will see the formation of a white precipitate, due to the low solubility of the salts; filtering is not required since the precipitate will
The collodion will be ready and perfectly transparent after 2 weeks time.The maturation phase liberates the halogens (Br, I) contained in the salts you added. This process will allow the transformation of the silver nitrate, contained in the sensitizing bath, into iodide silver and bromide silver which will cause your plate to be light- sensitive.
Developer
There are two schools of thought regarding fixing:
Potassium cyanide: which I strongly advise against because it is highly poisonous, dangerous.
Sodium Sulfite: Dissolve 150 grams of sodium sulphite in half a liter of distilled water. To facilitate dissolution, the water can be heated a little, remembering not to exceed 40 degrees.