This Ærst active material additive was intended to preserve
the spongy lead structure of negative plates. Besides pulver-
ized wood, other materials as diverse as lamp black, barium
sulfate, powdered charcoal, wood Øour and other assorted
wood extracts were used as additives. Additives to the
negative active material became a major topic once lead±
acid batteries stopped using wood separators that were the
norm in the Ærst half of the 20th century. Thus, it was the
wood separator that inspired the need to use additives in the
negative active materia