TONING 459 



Sulphide Redeveloping Solution 

 Stock Solution 



Sodium sulphide 45 g. lyi oz. 



Water to make 500 oc. 16 oz. 



For use, dilute 1 part stock solution with 8 parts water. 



After using this toner it is advisable to harden the prints. To do this mix the 

 following hardener: 



Hot water (125°F. or 52°C.) 150 cc. 5 oz. 



Sodium sulphite, anhydrous 15 g. ^^ oz. 



Acetic acid (28 per cent) 45 cc. IM oz. 



Potassium alum 15 g. 3'2 oz. 



After removing prints from sulphide redeveloper solution wash for 2 or 3 min. and 

 place in the above hardener bath for 5 min. Then wash thoroughlj^ for 30 min. 

 This hardener solution has no effect on either the color or gradation of the print. 



Mercury Sulphide Sepia Toner. — The four sepia toners just described depend on 

 the formation of one compound, silver sulphide, which, although it allows some altering 

 of the shade of brown by means of the nature of the original print image and by the 

 bleaching methods used, is essentially a compound with a limited range of colors. 

 By producing a combined silver sulphide and mercury sulphide image, the range of 

 tones available is lengthened. The addition of mercury sulphide to the image is 

 accomplished by adding mercuric chloride to the bleaching bath. The compound 

 formed in the bleaching is then a combination of a silver and a mercury salt. Upon 

 subsequent development with sodium sulphide, silver sulphide and mercury sulphide 

 are formed. By varying the amounts of mercuric chloride in the original bleach, the 

 color of the final print image is easily controlled; the larger the amount of mercury 

 used, the blacker or colder the image. The gelatin on the print has quite a strong 

 affinity for the mercury, and for this reason, after bleaching, the prints are bathed 

 in several changes of dilute hydrochloric acid to remove anj^ mercury which is in 

 combination with the gelatin. The mercury which is combined with the silver image 

 is not affected by this treatment, so there is no loss in the richness of the image. Mer- 

 cury sulphide is a compound just as stable as silver sulphide, so there need be no fear 

 of impermanence in images made of mercurj^ sulphide. The prints should be slightly 

 lighter than for the other processes as mercurj^ produces some intensification in the 

 toned print. 



Wash print well, eliminating all hypo. 



Bleach in bath made as follows : 



Mercury Sulphide Toner 



Solution A 



Potassium ferricyanide 30 g. 1 oz. 



Potassium bromide 45 g. l)-2 oz. 



Water to make 266 cc. 9 oz. 



Solution B 



Mercuric chloride 4 g. 60 gr. 



Potassium bromide 4 g. 60 gr. 



Water to make 150 cc. 5 oz. 



For 



Engraving black — 1 part A, 3 parts B, 16 parts water 



Warm black — 1 part A, 1 part B, 16 parts water 



Cold sepia — 1 part A, M part B, 12 parts water 



Normal sepia — 1 part A only, 12 parts water. (None of B added.) 



