508 HANDBOOK OF PHOTOGRAPHY 



Blotches, Lines, and Streaks 



Here are listed those defects of negatives which appear on the film or plate as white, 

 gray, or black (but otherwise usually uncolored) blotches, lines, and streaks. Blotches 

 are considered to be usuallj^ irregular in shape and larger than those defects which 

 might be classified as spots, which are treated elsewhere. The edges of lines are 

 usually sharply defined; in the case of blotches and streaks, the edges may be sharply 

 defined or not. 



Abrasion Lines and Scratches. 



lA. Distinguishing Characteristic. — Fine dark lines on the negative, frequently 

 straight; often appearing in multiple in which case they are usually parallel. 



2A. Cause. — Scratches caused by improper handling of the negative prior to 

 development. Such lines are often caused by dirt or grit abrading the emulsion. 

 Such grit vaay come from the interior of the camera, especially if a camera with large 

 IdcHows is employed, from the tables or other apparatus in the darkroom, or even from 

 unfiltered sources of water used for processing, (o) If the lines are parallel to the long 

 side of the film, they may easily have been caused bj^ dust, dii-t, grit, or even small burs 

 of metal in the roll film camera or in the film pack. Occasionally such lines may be 

 caused by scratching the surface of the negative with the dark slide of the plate or film 

 holder. (6) If the lines are at some random angle with respect to the edges of the 

 negative or if they are not straight, they may have been caused prior to development 

 or in the earl,y stages of development by abrasion of one negative with another or with 

 a gritty surface such as the darkroom table or developing traj''. 



3A. Prevention. — Absolute cleanliness is the best safeguard against such defects. 

 Films or plates should be loaded into their holders shortly before being used, and 

 should be inserted in the camera just before being exposed. The camera bellows 

 should be cleaned periodically. Processing tanks and trays should be wiped free from 

 dust and grit, and the water and other processing solutions should be filtered to free 

 them from foreign matter. Boxes containing imexposed negatives should be stored on 

 end to prevent pressure on top from bringing the emulsion into contact with other 

 surfaces which might scratch. 



4:A. Remedy. — Scratches are difficult to remedy, especially if they occur on minia- 

 ture negatives from which fairlj' large enlargements are to be made. Careful retouch- 

 ing may help in both contact and projection printing. The effects of scratches may 

 sometimes be minimized or eliminated in projection printing by dipping the negative 

 in glycerin after which it is placed between two sheets of glass before being placed in 

 the enlarger. Air bubbles must, of course, be removed. 



IB. Distinguishing Characteristic. — -Fine, light lines on the negative, frequently 

 straight; often appearing in multiple in which case they are usually parallel. 



2B. Cause. — Abrasion subsequent to fixing, usually occurring after the iiegative 

 is dried. In motion-picture and other miniature roll films, "cinching," i.e., winding 

 the film tighter when in roll form, especially where grit is present, is a frequent source 

 of trouble. 



ZB. Prevention. — Cleanliness and proper handling of developed film is the best 

 safeguard. Processed plates and negatives should be stored in a manner as to protect 

 them from scratches. Glazine or cellophane envelopes are especially suitable for 

 storing negatives. Roll film should be stored in dust-free boxes, should be handled as 

 little as possible, and should never be "cinched." Motion-picture film should be 

 reeled moderately tight with uniform pull during winding and should be stored in 

 dust-free containers. It likewise should not be "cinched." 



4^. Remedy. — (See A A above.) 



