At this time the silver nitrate bonds with the iodides and bromides in the collodion to make a light sensitive film of silver halides on the surface. While the plate is in the silver nitrate, the camera is set up and focused on the subject. The light sensitive plate is placed into a light proof holder and taken to the camera. The plate is wet and silver nitrate drips from the holder. The camera, which has been trained on the subject and focused, receives the plate holder.
Exposure is made by removing the lens cap and the time is counted.
It takes from 20 seconds to 5 minutes to make the proper exposure for a wet-plate negative depending on the age of the collodion and the quality of light on the subject. The plate holder is secured, removed from the camera and brought back to the darkroom. The plate is removed from the holder and the developer, a solution of iron sulfate, acetic acid and alcohol is poured onto the collodion side. The image becomes visible within a few seconds as the areas struck by light in the camera turn to metallic silver. When development is complete the developer is removed by a wash of clean water.