Page 115 - The Wellington photographic handbook

GENERAL HINTS ON PRINTING.
THE term P.O.P. is a contraction of "printing-out paper"
and is applied to photographic papers in which the image
prints out and can be watched during printing. Whilst
P.O.P. presents the advantage that the depth of the image can be
judged by looking at the print itself, it presents the disadvantage
that it can only be printed in bright daylight or by some intense
artificial light, such as the electric arc.
In ordinary artificial light P.O.P. can be handled freely, and
the packet can be opened and the paper put into the printing
frames in an ordinary room in daylight, provided the exposure
to the light is not unduly prolonged and the light itself is not very
strong. For example, printing could be done on the window sill
of a room, and the frames could safely be filled and emptied on a
table a few feet from the window.
As with Bromide paper, and if anything to an even greater
extent, it is important not to finger the surface of the paper. In
fact, except at the extreme edges which are to be trimmed off when
finished, it is best not to touch the sensitive surface at all.
It is easy to tell which is the sensitive side of the paper. It
is, of course, the shiny side, in the case of the Glossy and Carbon
papers, while in the case of the Matt, the sensitive side is smoother,
whiter, and more finished looking than the bare paper on the back.
There is always a slight tendency for the paper to curl with the
coated or sensitive side inwards.
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