Forming:
Forming is the process in which the active materials are formed on the plates. When a voltage is applied to the plates a thin film of lead peroxide is formed on the positive plate. If the charging polarity is reversed this thin film of peroxide (or PB02) will be converted to sponge lead on the negative plate. Sponge lead is a pourus form of lead. This increases the surface area available to the acid and thus increases the capacity. As this process of charging and reversal is continued the amount of sponge lead on the plates will increase. If continued indefinitely both plates will be entirely converted into sponge lead and fall to bits.