Matt is shooting a Pentax P3n and Fuji Superia 400, he is also using an experimental bleach bypass process. Something he noted upon mixing a fresh batch of chemistry… his first batch was mixed with sodium sulphate when it should have been sodium sulphite!
Matt says “Sodium Sulfate is an ingredient in detergent and has no real impact in photography. Sodium Sulfite is used in photography similar to fixer. Essentially, the Sulfate made no changes to the silver halides, while the Sulfite did. Since the Sodium Sulfate level used was relatively low, I still got photos. If it was higher, I probably wouldn’t have got any. This is closer to how I envisioned it. That being said – I kind of miss the old color shifts.”
The Frugal Film Project 