Fixing and Clearing 
Fixinc.—The rapidity with which plates, films, and papers 
fix is dependent on the strength of the bath, its temperature, 
and the degree of exhaustion or previous use. A 40 to 45 
per cent solution of hypo:is the strongest bath that should be 
used and is the most rapid in action. Plain, alkaline, acid, or 
acid and alum baths may be used. The first two are generally 
used for printing-out papers, and the latter for plates, film, 
and developed papers. In all cases, the temperature should be 
maintained about normal, 18° C. (65° F.). A bath should 
not be used too long, as the more it is used, the greater its 
saturation in silver salts, therefore, the longer it will take to 
fix properly and the greater the chance for the formation of 
insoluble, transparent silver salts which are difficult to wash 
out. 
The easiest way to make a solution is to tie the hypo 
crystals up in a cloth or piece of Canton flannel, and suspend 
in a vessel of hot water. This obviates any necessity for 
filtering the solution. 
Plain bath.— 
Hypo 400 g 64 oz. 
Hot water to 1000 ccm 16 oz. 
Alkaline bath—Generally used for silver printing-out 
images : 
Hypo 125¢ 24 oz. 
Sodium carbonate, dry 7g Y4 oz. 
Salt iis V4 oz. 
Water 1000 ccm 16 oz. 
Sodium sulphite, dry, may be substituted for the carbonate. 
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