It works exactly the same with the positive and negative reversed. does this mean that from a micro controller I would just need to put that pin low (or high if that was opposite to the base pin) to display, and then set the pin high (or low) to clear?
Static LCDs are supposed to driven with AC; for a segment to be on, the signal on its pin will be having opposite polarity to the respective common pin, or a segment to be off, the signal on its pin will be the same as the backplane/common. Attempting to drive segments with DC will degrade the LCD.
A couple of links that may help:
Static Driven LCD Technology
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