from each face of the
grid by means of a wooden paddle or trowel, and are smoothed off flush
with the surface of the ribs of the grid. This work is done quickly in
order that the pastes may not stiffen before they are applied.

U. S. L. plates are pasted in a machine which applies the paste to the
grid, subjecting it at the same time to a pressure which forces it
thoroughly into the grid, and packs it in a dense mass.

Drying the Paste. The freshly pasted plates are now allowed to dry in
the air, or are dried by blowing air over them. In any case, the
pastes set to a hard mass, in which condition the pastes adhere firmly
to the grids. The plates may then be handled without a loss of paste
from the grids.

[Fig. 6 Philadelphia diamond grid]

Forming. The next step is to change the paste of oxides into the
active materials which make a cell operative. This is called "forming"
and is really nothing but a prolonged charge, requiring several days.
In some factories the plates are mounted in tanks, positive and
negative plates alternating as in a cell. The positives are all
connected together in one group and the negatives in another, and
current passed through just as in charging a battery. In other
factories the positives and negatives are formed in separate tanks
against "dummy" electrodes.

The passing of the current slowly changes the mixtures of lead oxide
and lead sulphate, forming brown peroxide of lead (PbO2), on the
positive plate and gray spongy metallic lead on the negative. The
formation by the current of lead peroxide and spongy lead on the
positive and negative plates respectively would take place if the
composition of the two pastes were identical. The difference in the
composition of the paste for positive and negative plates is for the
purpose of securing the properties of porosity and physical condition
best suited to each.

[Fig. 7 Formed plate, ready to be burned to plate connecting
strap]

When the forming process is complete, the plates are washed and dried,
and are then ready for use in the battery. If the grids of two plates
have been cast together, as is done by some manufacturers, these are
now cut apart, and the lugs cut to the proper height. The next step is
to roll, or press the negatives after they are removed from the
forming bath so as to bring the negative paste, which has become
roughened by gassing that occurred during the forming process, flush
with the surface of the rib