DEFECTS IN NEGATIVES AND PRINTS 537 



temperature of the fixing bath should be between 60 and 70°F. (e) Properly com- 

 pounded fixing baths will prevent formation of colloidal sulphur. 



4. Remedy. — (a) If the opalescence is discovered while the negative is still wet, 

 it may be removed by immersing the negative in the fixing bath until opalescence has 

 completely disappeared. (6) Wash negative in clear water and dry slowly. If nega- 

 tive was incompletely fixed or incompletely washed, this treatment is not effective. 

 (c) Wash negative in clear water and drj^ slowly at temperature not above 90°F. and 

 preferably with atmosphere of 40 to 70 per cent humidity, {d) and (e) The stain or 

 opalescence of free sulphur on the negative may be removed by hardening the film 

 in a 5 per cent solution of formalin and by washing well with clear water. The nega- 

 tive should then be washed in a 10 per cent solution of sodium sulphite at 100 to 

 110°F. Obviously with such high temperatures, extreme care will be required in order 

 not to damage the negative in other respects. 



Yellow Stains. 



1. Distinguishing Characteristic. — Portions or all of negative colored yellow. 



2. Cause. — Yellow stains are frequent sources of trouble and may be caused by 

 a number of factors, among them being: (a) weak, exhausted, or improperly com- 

 pounded fixing bath; (6) exhausted or oxidized developing solution; (c) failure to rinse 

 negatives between developing and fixing, either with clear water or stop bath; {d) 

 uncleanliness in developing or impurities in the developer; {e) hypo or fixing bath in 

 the developer; (/) insufficient washing; {g) too much carbonate in the developing 

 solution; and {h) leaving negative incompletely covered in the fixing bath. 



3. Prevention. — When the most probable cause of the stain has been determined, 

 the preventive action will usually become apparent. 



4. Remedy. — Most of these stains can be removed by the methods suggested for 

 Developer Stains, page 535. 



Unevenness 

 Directional Effects. 



1. Distinguishing Characteristic. — Developed image appears to have "tail." 



2. Cause. — Directional effect of developer which enables image to be built up 

 more rapidly at one portion of the negative than at other. Also due to fresh developer 

 working on first parti of moving film during processing and partially exhausted 

 developer acting on later portions of film. Especially noticeable in certain types of 

 motion-picture processing. 



3. PreveJition. — Thorough agitation of solution during development so that the 

 developer at the surface of the negative is changed uniformly and rapidly during 

 processing. 



4. Remedy. — None. 



Uneven Development. 



1. Distinguishing Characteristic. — Streaks or areas of density different from the 

 normal density of the remaining portion of the negative. 



2. Cause. — Failure to immerse the negative entirely and completely in the develop- 

 ing bath, or permitting two or more negatives to come in contact in the developer for 

 appreciable time. 



3. Prevention. — The negatives should be immersed quickly and uniformly in the 

 developer and should be agitated during development, so that the solution may work 

 uniformly and completely over the entire surface of the negative. 



4. Remedy. — Local intensification may sometimes be employed to bring up the 

 density of the areas protected during development. 



