Wet plate collodion process was very involved :

* Clean the glass plate (extremely well) * Flow the glass plate with "salted" Collodion * Immerse the plate in a silver nitrate bath (3-5 min) * Expose the plate * Develop the plate * * Fix the plate (with potassium cyanide) * Varnish the plate

All of this was done in a matter of minutes, which meant that the photographer had to carry the chemicals with him wherever he went.