270 PHOTOMICROGRAPHY 



COLOUR SENSITISERS FOR PLATES 



Non-colour sensitive plates are made sensitive to the entire 

 spectrum by bathing in the following solution : 



Pinacyanol stock solution 2 parts. 



Pinachrome ,, 3 



Distilled water 50 ,, 



The stock solutions contain 1 part of the dye dissolved 

 in 1000 parts alcohol ; they can be bought ready prepared, 

 and keep well. The dilute solutions do not keep, and should 

 be mixed immediately before use, and not used more than 

 twice. 



Bathing is carried out in the same way as development, 

 either in a dish or tank, in complete darkness or by the light 

 of a panchromatic safelight. 



Bathing in a Dish. Immerse the plates for 3 minutes, 

 rocking continuously. 



Tank. Dilute the above solution 20 times and leave the 

 plates in it 20 minutes, reversing the tank once or twice. 



Wash the plates in running water for 5 minutes and place 

 on a rack to dry, preferably in a dark cupboard through which 

 a current of dry air can be passed and kept at about 80 F. 



FIXING BATHS 



For negatives. Hypo (sodium 



thiosulphafce) . . 4 to 8 ozs. 



Water 20 or 20 to 40% 



For prints. Hypo 3 ozs. 



Water 20 or 15% 



ACID FIXING BATH. For plates, lantern slides, bromide and 

 gaslight papers. Cleaner than plain hypo, and stainless. 



Hypo . . 4 to 6 ozs. or 200 to 300 grammes 



Potassium meta-bisulphite . . J oz. ,,25 ,, 



Water 20 ozs. 1000 c.c. 



HYPO ELIMINATOR. Place the plates or papers in several 

 changes of water to which sufficient potassium permanganate 

 solution has been added to give it a pale pink colour, until the 

 pink colour is no longer rapidly discharged. Then rinse in 

 water. Too strong a solution acts as a reducer. 



