"Wet plate photos are created on glass sheets of varying sizes but for portrait work the sizes are most frequently 5x7 or 8x10 inches.
Using a combination of chemicals in the darkroom each plate is made light sensitive minutes before the exposure is made in the camera and then returned to the darkroom immediately after exposure for development — the light sensitive emulsion created in the darkroom must stay wet during the entire procedure, hence the name “wet plate” photography.
Part of the charm of the wet plate look is the inherent unpredictability of the process. The way in which the various chemical treatments flow across the glass plate in the darkroom create a texture and variation in the tonality of the image. The effect is not repeatable from plate to plate giving each photograph a uniqueness that is not available from any other photographic process.
The photo is visible for a preview within 10 minutes of the exposure but takes approximately a week before the emulsion has cured and the finishing touches can be applied to the glass plate. Print (paper) copies can be made, but the decision to make print copies must be made before the plate is finished and delivered.” — Fred Fraser