When I started on my iPhone back project I actually researched wet plate photography, the process of putting an emulsion on glass, exposing it, and developing it into an image. How awesomely steampunk that would be!
However, though I've done a little black and white developing and printing in the distant past, I am by no means skilled in this discipline.
However, Jake Potts was thinking along the same lines and had the mad skillz to bring his project to fruition!
Click through to view his process and the results.