No mention of lightening! The idea that the triboelectric series is more guidelines than rules was interesting, but the metal-insulator distinction seems a bit off. Is there a triboelectric effect between two conductors? How? Why wouldn't the distribution of electrons even out in a pair of conductors, or do they mean non conducting metals? And I imagine someone has looked at triboelectric effects between crystals of varying materials - does anyone know?

> Two experiments using the same sets of materials may yield two distinct orderings of the materials.

A quantum static effect?