So this episode from the B&H Podcast isn't technically about polaroids, but it does talk extensively about the polaroids of the 19th century, also known as tintypes. The podcast also covers cyanotype, wet plates, daguerreotype, calotype, gum bichromate and spirit photography. An hour of all things alternative and I love it. Check out the Penumbra Foundation and the Halide Project to learn more about alternative photo processes and how you can get involved.