DEFECTS IN NEGATIVES AND PRINTS 535 



2. Cause. — Stains produced during development (see Developer Stains). 



3. Prevention. — (See Developer Stains.) 



4. Remedy. — (See Developer Stains.) 



Developer Stains. 



1. Distinguishing Characteristic. — ^Local or general staining of the negative. 

 Developer stains are usually yellow, brown, or sepia, although the color depends upon 

 the developer used. May be produced either in developing or fixing bath. 



2. Cause. — Developer stains may be caused by: (a) alkaline or old fixing bath, 

 (6) old or discolored developer, or (c) developer containing impure or insufficient 

 sulphite. Certain developers, such as pyro, for instance, are much more likely to 

 stain the negative than other developers. If the stain is general and uniform, the 

 contrast may be altered, and the printing time may be increased without other unde- 

 sirable effects being present. 



3. Prevention. — The use of fresh and properly compounded processing solutions is 

 essential. Care should be taken to see that the developer contains the proper amount 

 of sulphite. Nonstaining developers, such as metol-hydroquinone, may also be used. 

 Increasing the amount of sulphite in the developer will help prevent stains. 



4. Remedy. — Harden the negative in a solution of 10 cc. of formalin and 5 g. of 

 sodium carbonate per liter of solution, and wash in clear water for 5 min. Bleach 

 in equal parts of: (o) 5.3 g. of potassium permanganate per liter, and (b) 75 g. of 

 sodium chloride and 16 cc. of sulphuric acid per liter, making sure that all particles are 

 thoroughly dissolved before the two solutions are mixed. Bleaching should be com- 

 pleted in about 4 min. The brown stain which is produced may be removed by 

 immersing the negative in a 1 per cent solution of sodium bisulphite. The negative 

 should then be rinsed well and developed in strong light with a nonstaining developer. 

 Local yellow stains may be handled by making a new negative or a print from the 

 stained negative through the use of a strong yellow filter. 



Dye Stains. 



1. Distinguishing Characteristic. — Areas of negative that are colored red, green, or 

 other color, especially at the edges where developer may not have reached negative 

 completely, as in tank development. 



2. Cause. — These stains are those of the sensitizing dyes used in the manufacture 

 of some orthochromatic and panchromatic films. The stains are due to incomplete 

 removal of these dyes because the developer and fixing bath are kept from free cir- 

 culating contact with the back of the negative. The effects are often observed in 

 tank development where the film has been inserted in a holder or frame which prevents 

 free circulation at the edges of the negative. 



3. Prevention. — Thorough agitation of the. negative during development. 



4. Rem,edy. — Thfese dye stains are soluble in water and consequently may be 

 removed subsequent to fixing by immersing in clear water until the stains have 

 disappeared. 



Fading. 



1. Distinguishing Characteristic. — Brown or yellow stains on parts of the negative, 

 or covering the entire negative, apparent some time after fixing. 



2. Cause. — Incomplete fixing or, more usually, incomplete washing. 



3. Prevention. — Complete fixing and washing. 



4. Remedy. — (See remedy for removal of Developer Stains, above.) 



