Sulphide Toning 
There are two principal methods of obtaining warm brown 
or sepia to purplish brown tones: the direct and the indirect. 
In the former, the image is converted into silver sulphide 
direct, while in the latter process the silver is first converted 
into chloride, bromide or iodide, and then into sulphide. 
Direct Processes.—Alum and hypo (Baekeland).— 
Hypo 200 g 3 l/Siez, 
Potash alum 46 ¢ 354 gr. 
Water 1000 ccm 16 oz. 
Dissolve the hypo, keeping the temperature of the solution 
near the boiling point, add the alum gradually with constant 
stirring, and allow to cool. Heat up to 50° to 60° C. (122° 
to 140° F.) each day for three days, and then add: 
Silver nitrate, 10% sol. 5to7Zccm 40to55 min. 
The bath must not be filtered. 
Alum-sugar-hypo (Baekeland).— 
Hypo 25 ¢g 192 gr. 
White sugar 40g 307 gr. 
Alum 25g 192 gr. 
Hot water 1000 ccm 16 oz. 
Mix as above. It is advisable to wash the prints thoroughly 
after fixing, and with some papers it is advisable also to 
immerse for 5 minutes in an alum bath, then briefly wash and 
tone. The bath should never be above 44° C. (110° F.), the 
best results being obtained at about 32° C. (90° F.), though 
toning at this temperature takes 30 minutes. 
Alum and hypo (Artura).—Specially recommended for 
development (gaslight) papers, but equally suitable for 
bromide prints: 
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