Thanks for all your input and pics everyone, reading between the lines it would seem we would all like to keep the pot at a constant temp so we can concentrate on the colour rather than juggling temp controls, it makes sense really.
The electric hob is here now but I ended up finishing the parts on the gas stove to save time, as soon as the bench is clear and there's time to do some experiments, I'll give it a go and see how good (or bad ) the temp control is. I'm tempted to try the pid controls but may get an electric lead melting pot and fit the sensor and controller to that, hopefully I'll find a way to save some time and produce consistent colours.
