At Corsair Artisan Distillery in Nashville, where I work, we came across a 1920s copper still that escaped Prohibition, and we were dying to put it to good use. Unfortunately, it was missing the crucial piece that allows us to view temperature readings, which reveal everything about the distillation process from beginning to end.
In addition, we’ve got a bit of a time pinch when the liquid begins to foam — we have to cut the heat within 10 seconds so it doesn’t boil over into the batch. Foam-over in a still run is catastrophic!
To prevent it, distillers either use a silicon anti-foaming agent (yuck), or, like us, they use their eyes to visually monitor it through a sight glass and then adjust the heat accordingly. During each distillation, we wait for the foam to pass by the sight glass, and then cut the heat to let the mash settle. After 5 minutes, we turn the heat back on at a lower setting and let it roll for the remainder of the distillation.
When you want a monotonous task to just work itself out, day after day, learn Arduino. Recently, I had messed around with Arduino to turn things on and off, and I knew I could wire up a couple of temperature sensors and view the still’s temperature on an LCD screen.
I found a photoresistor that could measure light, wired it into the microcontroller, and placed it over the sight glass. There’s a significant light shift when the light reflects off the foam. I wired a 12V motor to the still to control the heat, and a water on/off valve to control water flow to the condenser. This way, the Arduino could have a “digital eye” into the sight glass, watching relentlessly for the foam and controlling the heat accordingly.
I spent some time perfecting the code, and now we pump in the liquid, flip a switch, and walk away. The Arduino handles the rest.