Page 36 - The Wellington photographic handbook

WELLINGTON Ortho Process Plate.
This plate is specially made for process workers, for whom
it is very suitable owing to its extremely fine grain, its general
cleanliness, and its orthochromatic qualities. It is also of the
highest value for copying purposes and for all photographic work
where a colour-sensitive plate giving great density is required.
Its manipulation does not differ from that of the other WELLING-
TON Plates.
Any of the developers previously mentioned will be found
suitable.
The following is recommended where great contrast is required.
It should not be used at a temperature below 60° Fahr.
HYDROKINONE.*
Hydrokinone 80 grains 5 grammes
Sodium Sulphite (cryst.) ... 1 ounce 30
Potassium Hydrate 80 grains 5
Potassium Bromide 10 „ 0-6 gramme
Water to 20 ounces 500 c.c.

HALATION.
"
Mention has been made in the preceding pages of " halation
and " backed " plates. These terms require a little explanation.

The beginner at photography will soon discover that when
he photographs subjects in which there are deep shadows and very
bright high-lights his negatives show the high-lights spread beyond
their proper boundaries and consequently blotting out the details
of the surrounding parts. This is particularly noticeable in photo-
graphs of interiors in which windows appear, or in the case of
landscapes where trees stand out against a bright sky. This
spreading of the high-lights is termed " halation " and is due to the
fact that the bright light is not wholly absorbed by the film, but
in part passes through, and reaching the back of the plate, is reflected
at an angle upon the underside of the film.
* Before making up any formula, read the notes on pages 1 25, 1 26 and 1 34.
26