COLOR PROCESSING Color adds realism to photographs. At one time color  was  difficult  to  work  with.  It  required  special cameras and specialized films that could be processed only by the manufacturer of the film. Now, color materials  have  been  improved  and  are  used  extensively in the Navy. They are far more popular than black and white. As discussed in chapter 2, color films have at least three  emulsion  layers.  Primary  colors  affect  one emulsion  layer  only,  while  complementary  colors  affect two emulsion layers; for example, the color cyan affects the blue and green sensitive layers. White light affects all three emulsion layers. Black has no effect on any layer. The type of process used depends on whether the film is a negative type of film or a reversal (slide) film. The most common processes used in the Navy are Kodak  Flexicolor  for  color  negatives  and  Kodak Process E-6 for color reversal films. The Eastman Kodak  Company  continually  strives  to  improve  their processes by making them more environmentally safe. Always consult the Photo-Lab-Index for the most current   information   concerning   film   and   paper processes. COLOR  NEGATIVE  PROCESSING In negative color film, the dye couplers produced are complimentary to the primary colors of light; therefore, a blue light records as yellow, a green light records as magenta, and a red light records as cyan. All colors  within  a  scene  are  recorded  through  varying combinations  of  these  yellow,  magenta,  and  cyan  dyes. The color negative is a halfway stage to a color print. The  cyan  and  magenta  dye  image  layers  formed  by color processing absorb some light wavelengths that should  be  transmitted.  In  negative  color  film,  these absorbed wavelengths of light cause a color cast when printed. To prevent this color shift, the manufacturer has given  the  green  and  red  sensitive  emulsion  layers  a yellowish  and  pinkish  tint,  respectively,  during manufacturing. These tints are what form the overall orange mask that you see in finished color negatives. Some color film used for aerial photography does not have  this  orange  mask.  This  allows  for  a  direct interpretation  of  the  negative  image.  An  orange- masking  filter  is  added  when  these  films  are  printed. The  Kodak  Flexicolor  process  is  used  for processing  color  negative  films  and  some  monochrome film, such as Ilford XP2. There are four chemical steps and two wash cycles in the Flexicolor process. They are as follows: color developer, bleach, wash, fix, wash, and stabilizer. Color  Developer The first step in color negative processing is color development.  A  color  developer  in  color  processes works nearly the same as a black-and-white developer. The  exposed  silver  is  developed  by  a  developing  agent and converted to metallic silver and by-products are released.  As  the  color  developer  is  working  at developing the silver, it becomes oxidized and reacts with nearby dye couplers. Dye couplers are built into the emulsion around all of the metallic silver sites. The primary function of a color developer is to develop the exposed silver halide crystals to metallic silver and then form  dye  around  the  metallic  silver,  using  the  oxidized color  developing  agent. Temperature  of  the  color  developer  is  the  most critical of all the processing steps. The temperature of the color developer must be 100°F ±0.25°F (37.8°C ±0.15°C). All other wet steps in the process can be within the range of 75°F to 105°F (24°C to 41°C); however, it is best to maintain all solutions at constant temperatures. Bleach Bleach is found in all color processes. The purpose of the bleach is to take the metallic silver still in the color film (or paper) and convert it to a form that can be fixed. In color products, all of the silver must be removed. Only  the  color  dyes  form  the  image.  The  bleach chemically converts the silver metal back to a soluble silver  halide. Fixer The function of fixer is the same in color processes as it is in black-and-white processes. A fixer converts the silver halide to a water soluble form. Most fixers use thiosulfate as the fixing agent in an acidic solution. When  fixing  is  incomplete,  unwanted  silver  remains  in the image. This causes a loss in contrast, added density, and an unwanted color cast. Stabilizer The final wet step in color negative film processing is the stabilizer. The main purpose of this solution is to provide a wetting agent to prevent spotting of the film and to prevent unused magenta dye couplers from attacking  the  newly  formed  magenta  dye. 10-26