RAD 254 Chapter 12 Processing the Film Latent Image

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RAD 254 Chapter 12 Processing the Film Latent
Image

• Basics/Dates
• Universal time and temp 5 min at 68 degrees F
• Each MAJOR step is 2X longer than the previous

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• 1942 First Automatic Processor by Pako (some
  20 ft. long and required film to be placed on
  hanger racks for transport)
• 1956 First roller transport processor by
  Kodak (5 minute)
• 1965 First 90 sec processor by Kodak
• 1987 First 45/90 sec variable processor by
  Konica

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• Development conversion of latent image to
  manifest image (black metallic silver)
• Fixation
• Removes the UNEXPOSED silver halide crystals
• Preserves the image

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Automatic Processor (90 sec)Items of importance

• Time for devel and fix 22 seconds for each
• Developing agents Hydroquinone,
  phenidone/metol/elan
• Fixing agents Acetic acid, ammonium thiosulfate

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Developing agents

• Hydroquinone SLOW acting build up of blackest
  blacks (also known as the reducing agent)
• Phenidone/metol/elan act RAPIDLY to build up
  GRAYS
• Buffering agents (to maintain alkalinity)
  sodium carbonate/sodium hydroxide (Lye)
• Restrainers Potassium bromide/iodide
  prevents developer from converting the UNEXPOSED
  silver halide to black metallic silver

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Devel. Cont.

• Preservative sodium sulfite
• Hardener Gluteraldehyde (others used potassium
  alum, aluminum chloride, chromium alum

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Fixing Agents

• Same hardener and preservatives as devel.
• Acetic acid activator stops action of
  developer
• Ammonium thiosulfate FIXING AGENT
• Acetate Buffering agent helps maintain
  proper pH

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Washing

• Universal solvent Water
• Hypo retention residual chemicals on the film
  turning the film brown over time
• MUST BE CHECKED FOR MAMMO

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Automatic Processing

• Six total systems
• Transport
• Temperature
• Circulation
• Replenishment
• Dryer
• Electrical

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Transport

• Rollers and transport racks, drive gears
• TRANSPORT ROLLERS are 1 in diameter (3.14
  circum.) Pi lines are a common artifact
• Guide shoes also can cause artifacts
  (especially with new processors and racks)
• Cross over rollers
• Time guidelines -2 percent of required time

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5 other systems

• Temperature proper temps. For developer, wash
  and dryer
• Circulation agitates chemicals, FILTERS
  DEVELOPER
• Replenishment meters and replaces chemistry
• Dryer Dries film (know diff. between wet and
  tacky
• Electrical All electrical areas

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Special Processing

• Daylight Enables one to place a cassette in the
  daylight processor and the processor
  opens/processes/reloads cassette
• Dry Processing
• Photothermic Used laser to form a latent image
  and HEAT to make it visible
• Thermographic Uses heat to DIRECTLY produce the
  image