For this process, we took only a day to go over it, really more for fun than a proper lesson.  Our professor Josh shoots primarily in wet plate collodion, so he was able to give us an expert demonstration and practice session.  The process was invented in 1851 when Frederick Scott Archer discovered collodion could be used as a substitute for egg whites on glass photographic plates.  For this process, you take a metal plate that has been coated and apply a layer of collodion solution.  Collodion is a highly flammable, syrupy liquid composed of nitrocellulose (aka gun cotton, flash paper, flash cotton) in ether and alcohol (hence doing this at school, not at home).  Time is of the essence in this process as the plate needs to remain wet from beginning to end (hence the name 'wet plate' collodion).  Once the plate has been coated in the collodion solution and the solution has set, you submerge it in a silver nitrate solution, which makes the plate photo sensitive.  After 3-5 minutes, you remove the place from the silver nitrate bath, let it fully drain off, then place it in the photo cartridge.  You can then take your picture using a special camera (think old-school where the photographer had a cape over him and the back of the camera).  Once you have exposed the plate in the camera, you take the cartridge back into your darkroom and develop it, then fix it using potassium cyanide.  Once it has been rinsed and dried, you apply a layer of varnish composed of sandarac, alcohol, and lavender oil.  Not only does this prevent the plate from tarnishing, but it smells nice, too! 

4x6 Tin Type1
4x6 Tin Type2