Dear Sam,
The colour of sepia toning is dependent on a number of factors.
Firstly, it depends on the toner composition. If you are using a direct
sepia toner based upon sodium sulphide (the smelly one!) then dilution,
initial paper developer, temperature and more importantly, emulsion
composition are all contributing factors. Chloro-bromide (warm) papers tend
to produce warmer, redder hues. Bromo-chloride papers, eg. Ilford
Multigrade VC, will produce a more browner hue. Pure bromide papers will
produce a cold brown colour. With direct toners such as Agfa's Viradon,
adjusting the dilution from 1:25 to 1:200 will also produce a remarkable
range of diiferent sepias, even with the same emulsion. The temperature of
the toning bath is probably the least significant variable.
With indirect (re-halogenating) toners, based upon thiocarbamide, the
variables affecting hue are composition of the bleach, alkalinity of the
toner and again, paper composition. Once more,temperature is only a minor
contributing factor. The bleach is made by adding sodium chloride to
potassium ferricyanide to make a chloride bleach, or potassium bromide to
pot. ferri, to make a bromide bleach. If you are feeling particularly wild,
then you can even make a iodine bleach by adding potasium iodide to pot.
ferri. In general, chloride bleaches produce a warmer more yellow tone than
do bromide bleaches, but again this is emulsion related.
A thiocarbamide toning bath will produce a more purple/brown by increasing
its alkalinity (adding more sodium hydroxide) and a more yellow brown by
adding the minimum amount of sodium hydroxide.
This really is only an insight into sepia toner chemistry. There are many
good books on the subject. Try 'Creative Elements' by Eddie Ephraums.
Finally, if you like red warm tones, try treating a well washed,
sepia-toned print with a dilute selenium toner.
Merry Christmas! ... Tony McLean.
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