530 HANDBOOK OF PHOTOGRAPHY 



Hardening the negative prior to processing will also help prevent formation of blisters, 

 especially in hot weather. Replacing carbonate in the developer by a noncarbon 

 dioxide forming substance, such as borate or phosphate is another way of avoiding 

 blisters. 



4. Remedy. — None. 



Brittleness. 



1. Distinguishing Characteristic. — Film is too brittle and dry. 



2. Cause. — Brittleness is usually the result of (a) drying the film too completely 

 or in an abnormally dry atmosphere, (6) the use of hardening stop baths, or (c) excess 

 hardener in the fixing bath. 



3. Prevention. — To maintain its pliabilitj^, film must contain a certain amount 

 of natural moisture, which can be provided bj^ maintaining the film in an atmosphere 

 of 70 per cent relative humidity. The relative humidity of the atmosphere during 

 the drjdng of the film should be between 40 and 70 per cent. 



4. Remedy. — Brittleness can be remedied by submitting the films to storage in an 

 atmosphere of 40 to 70 per cent relative humidity, as in humidifying tanks. 



Buckle. 



1. Distinguishing Characteristic. — Waviness in the center or along the edges of the 

 film. 



2. Caiise. ^Buckle is due to nonuniform expansion or contraction of the negative. 

 Buckle is commonly produced by (a) drying the film in an atmosphere of high humidity, 

 (fe) forced drying at high temperature, or (c) drying in atmosphere of too low humidity. 



3. Prevention. — Buckle can usually be prevented by proper drying conditions. 

 For proper drj^ing the relative humidity should be between 40 and 70 per cent and the 

 temperature should not exceed 90°F. 



4. Remedy. — Buckled film frequent!}^ vn&y be improved by soaking in water and 

 drj^ing in a properly conditioned atmosphere. Buckled motion-picture film may often 

 be freed from buckle by winding the film on a dry reel and placing it in a relatively 

 humid atmosphere. 



Creeping. 



1. Distinguishing Characteristic. — Creeping or movement of emulsion on its 

 supporting surface.. 



2. Cause. — Insufficient ventilation and high temperature during drying. 



3. Prevention. — Proper drying conditions. 



4. Remedy. — None. 



Curled Negatives. 



1. Distinguishing Characteristic. — Negatives not flat but curled. In extreme cases 

 they may be curled up into a tube. 



2. Cause. — ^Difference in contraction or expansion coefficient between that of the 

 emulsion and that of the gelatin support. Since the emulsion contracts more than 

 the gelatin, the film curls with the emulsion on the concave or inside surface. 



3. Prevention. — Modern films are so made that excessive curling is largely elimi- 

 nated. Drying negatives with clips or weights attached to the bottom edge will keep 

 the negatives straight during drying and will help prevent curling. Storing dry 

 film fiat tends to keep it so, whereas storing films in rolls tends to aggravate curling. 



4. Remedy. — After films are thoroughly dry, they may frequently be relieved from, 

 curling by placing them between sheets of clean white paper and applying pressure 

 as by placing them between the leaves of large books. Another method, which may 

 be used if care is taken, is to press the film between two sheets of clean white paper 



