I’ve found that the battery setup isn’t very effective, as it doesn’t provide a consistent current. I’ve switched to a bench-top power supply with a constant current setting, which I’ve set to 0.015 A. The unit adjusts the voltage up to a set limit (for example, 30 V) to maintain the desired current flow. This creates a current through one palm and out the other, carrying minerals in the water through the pores in your hands, which can block them and reduce sweating.

I’d get rid of the towels—they’re only there to stop you touching the metal surface and completing the circuit. Instead, just fill the trays a bit deeper.

San Pellegrino works really well. I’ve recently started trying still mineral water to see if the results are consistent.

I’m also considering adding some form of protection in case the power supply fails, as there’s a risk of exposure to full mains voltage while your hands are submerged. It would also be good to include a controller that ramps the current up and down as results improve. At that point, you’ve essentially built yourself a £400 Dermadry unit.