Heating Methods for C-41: Which One Wins?
Precise temperature control is one of the hardest engineering problems in an automatic film developing machine. C-41 color chemistry requires 38°C ± 0.5°C — miss that window and your colors shift. For a machine that should work autonomously, I needed to know which heating method is actually reliable, fast, and simple enough to build into the final design. I ran a systematic experiment comparing five different heating approaches, with and without active stirring, measuring both speed and temperature stability at target. ...