Expose the plate by removing the lens cap. This will allow light to enter the camera and strike the light-sensitive collodion.
Expose the plate for 20 seconds to 5 minutes. (Exposure time depends on how fast the silver halides react to light, how much light enters through the lens, and the amount of light hitting the subject.) Replace the lens cap to end the exposure.
Reinsert the holder's slide. The holder can now be safely removed from the camera and taken back to the darkroom or dark tent.