Page 87 - The Wellington photographic handbook

at which to light the magnesium. At this distance a piece of
magnesium ribbon half an inch long will be found about right for an
average negative. The exposures should be varied by altering the
length of ribbon burnt, not by varying the distance from the flame.
A pair of pliers, or two coins, make a convenient holder for the
ribbon, and a piece of card or blue glass should be held before the
eyes while the ribbon is burning, or it will not be easy to see to
develop immediately afterwards.
If printing is to be done by daylight, then, in a moderate
light from one to three seconds will probably be found correct.
S.C.P. can also be used for enlarging, both by daylight and by
artificial light, full instructions for which will be found in the
chapter on enlarging on pages 76 to 89.
DEVELOPING S.C.P.
The following are the formulae which will be found most suit-
able for developing S.C.P.
METOL-HYDROKINONE DEVELOPER.*
Metol ... ... ... ... 20 grains 1 gramme
/> . Hydrokinone ... 60 ,, 3 grammes
Op* a^JU^i — Sodium Sulphite (cryst.) 700 „ 35
,
-q .. — Sodium Carbonate (cryst.) 700 „ 35
^f" 7 ' Water to 20 ounces 500 c.c.
j J i*ti <-v/i— Potassium Bromide ... 6 0-3 gramme
The ingredients set forth should be mixed in the order named, each one
being completely dissolved before adding the next.
This developer keeps almost indefinitely in well-stoppered bottles.
For the " Soft " grades of S.C.P. this developer should be diluted with//
V an equal quantity of water. //
N.B.—All metol-hydrokinone developers should be used at a temperature
of from 60° to 65° Fahr. Below 60° Fahr. hydrokinone rapidly loses its
developing power, and at very low temperatures becomes practically inert.
AMIDOL (DIAMIDOPHENOL) DEVELOPER.*
TZJs** <&lJ*mcI — Sodium Sulphite (cryst.) ... 1000 grains 50 grammes
. .
v Amidol (Diamidophenol) ... 100 „ 5
*u~.**,o icfyti^-' Potassium Bromide 4 ,, 0-2
Water to ... ... ... 20 ounces 500 c.c.
The ingredients should be mixed in the order named, the sulphite being
dissolved before the amidol is added.
This developer, which gives brilliant cool black tones, will keep good
for three days only. After that time it should be discarded and fresh made
up.
For the " Soft " grades of S.C.P. this developer should be diluted with
an equal quantity of water.
* Before making up any formula, read the notes on pages 125, 126 and 134.
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