Page 21 - The Wellington photographic handbook

GENERAL REMARKS.
THE instructions which follow apply to all the different kinds
of WELLINGTON Plates—except the Lantern Plates
and S.C.P. Lantern Plates, which are dealt with separately
on pages 98 to 110—and should be read through very carefully
before any plates are used.
All photographic plates are extremely sensitive to light. The
packets in which they are supplied must, therefore, be opened
in the dark-room, and this room must be so lighted as to be reason-
ably safe. By this is meant that the lamp or window which serves
to illuminate the room must be provided with a sheet of glass, or
some other material, of such a colour as to absorb all the actinic
rays and allow only those to pass which are incapable of fogging
the plate. A piece of deep red glass, or better, one of red and one
of yellow bound together, form a suitable filter for most plates ; or
if preferred a sheet or two of special fabric, sold for the purpose by
photographic dealers, may be sandwiched between two pieces of
plain glass and used instead.
Daylight is not a good dark-room illuminant, as not only does
its strength vary from hour to hour, but its actinic power is such
that special niters are necessary to render it safe. Artificial light
is much to be preferred in this respect, and, being constant, is less
liable to lead to error in estimating density during development.
In buying a dark-room lantern the reader will be well advised
to pay a fair price rather than content himself with a cheap article,
which later on may cost him dear in fogged plates,
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