1. Creating the Image
Unit III

2. Film Processing
Chapter 20

3. Objectives Explain process of film developing and fixing
Describe synergistic properties of automatic processor reducing agents
Identify primary chemical and its function for each developer and fixer agents

4. Objectives Explain washing and drying processes of film archiving
Describe functions of subsystems of automatic processor

5. Objectives
Discuss basic function of radiographic darkroom design and safelights
Explain rationale for use of silver recovery system

6. Purpose of Film Processing
To accumulate enough black metallic silver at sensitivity specks to yield visible film image
Due to predominance of digital imaging, very little chemical processing still done in developing nations

7. Purpose of Film Processing
Film processing involves four steps:
Developing
Fixing
Washing
Drying

8. Developing First step in wet processing
Results in visibility of silver at latent image sites

9. Developing Consists of: Reducing (primary) agents Activator Restrainer
Preservative
Hardener
Solvent

10. Reducing Agents Provide free electrons to silver ions
Through “gates” of exposed sensitivity specks
Reduction/oxidation

11. Reducing Agents Two reducing agents work synergistically
Phenidone (P developer)
Works quickly to produce shades of gray

12. Reducing Agents Two reducing agents work synergistically
Hydroquinone (Q developer)
Works slowly to produce black areas

13. Reducing Agents Used developer becomes oxidized
If not properly replenished, changes color from deep amber to brown to rust-red

14. Activator Typically sodium carbonate
Added to developer to maintain alkaline pH
Helps reducing agents get to silver halides
Swells gelatin
Making it easier to penetrate

15. Activator Makes developer solution caustic
Should wear rubber gloves and apron
Neutralize spills with fixer or dilute with water

16. Restrainer Typically potassium bromide
Provides distraction to overactive reducers
Prevents developer from acting on unexposed silver halide crystals

17. Preservative Developer easily oxidized by air
Sodium sulfite decreases this oxidation process
Careful tank design can reduce developer’s exposure to air

18. Hardener Glutaraldehyde Controls swelling of gelatin
Prevents abrasions during processing
Maintains uniform film thickness

19. Hardener Low levels of hardener allow gelatin to stick to rollers
Can cause processor jams and/or artifacts on films
May present as moist, sticky films
Even after being dried

20. Hardener Too much hardener will harden emulsion too soon
Prevents chemical interactions from happening
Traps moisture in gelatin

21. Solvent Water Should be filtered In tropical areas
5-10 micrometer filter
In tropical areas
Should be treated for bacteria and fungi

22. Contamination Developer impacted by contamination
0.1% of fixer present in developer will stop action of reducers
Results in gray, low-contrast films
Developer carried into fixer tank routinely
Thus, developer does not contaminate fixer

23. Contamination Can be avoided by using splash guards
When cleaning processor:
Fixer tank should be filled
Developer tank should be cleaned

24. Contamination When shutting down processor: Lid should be opened
Prevents fixer condensation from dripping into developer tank

25. Fixing
Undeveloped silver halides must be removed from film

26. Fixing Consists of: Clearing (primary) agent Activator Preservative
Hardener
Solvent

27. Clearing Agent Usually ammonium thiosulfate
Bonds with unexposed silver halides
Becomes ammonium thiosilversulfate

28. Clearing Agent Films will appear milky if not properly cleared
Typical clearing time:
15-20 seconds
Manual processing:
2-3 minutes

29. Activator Acetic acid maintains acidic pH
Enhances function of clearing agents
Neutralizes developer solution
Stops action of reducers

30. Preservative Sodium sulfite
Removes silver from ammonium thiosilversulfate
Allows ammonium thiosulfate to continue to remove silver halides

31. Hardener Glutaraldehyde only works in alkaline
Fixer hardener is aluminum chloride, chromium alum, or potassium alum
Serves same purpose of developer hardener
Maintains film thickness

32. Solvent
Filtered and treated water

33. Depletion Fixer eventually becomes silver saturated
Clearing time gets longer
Replenishment prevents depletion
Silver recovery removes silver from used fixer solution

34. Washing Water removes as much chemistry as possible
Temperature should be 5º F (3º C) lower than other solutions
If too cool, emulsion will reticulate
Film will have crackled appearance

35. Washing If fixer not washed from film: Proper washing requires:
Film becomes yellow and then brown with age
Proper washing requires:
Agitation
Enough time

36. Washing Wash tanks prone to algae and bacteria growth
Tank should be drained when processor shut down

37. Drying Accomplished by forcing hot air over both sides of film
º F (43-65º C)
Hardens emulsion and seals supercoat

38. Storage 70º F (23º C) and 60% humidity
Length of storage dependent on state law and institution
Usually 5-7 years
Minor and legal cases indefinite
Mammograms

39. Automatic Processors First introduced by Kodak (1957)
Utilizes sub-systems:
Transport
Dryer
Replenishment
Circulation
Temperature control

40. Transport System
Moves film through developer, fixer, washer, and dryer sections
Controls length of time radiograph is immersed in each solution
Agitates chemistry

41. Dryer System Final stage of processing Squeegee crossover rollers
Removes excess water
Blows hot air through slotted tubes
Film emulsion shrinks and seals

42. Replenishment System Replaces chemicals as they are depleted
Two types of replenishment:
Volume
Flood

43. Replenishment Rates 4-5 ml of developer/inch of film
6-8 ml of fixer/inch of film

44. Mixing Solutions
Must be done according to manufacturers’ specifications
Starter solution
Acetic acid and potassium bromide
Must be added to fresh developer chemistry

45. Developer Starting and Seasoning
Adequate mixing of developer chemistry necessary
Requires running processor for minutes prior to processing films

46. Processor Solution Safety
Hazardous materials
Occupational Safety and Health Administration (OSHA)
U.S. Environmental Protection Agency (EPA)

47. Processor Solution Safety
Material Safety Data Sheet (MSDS)
Protective eyewear/eyewash
Rubber gloves and apron

48. Circulation System Stabilizes temperature Agitates and mixes chemistry
Filters solutions

49. Temperature Control System
Maintains all three solutions at compatible temperatures

50. Darkroom
Safelights
Entrance
Pass box
Ventilation

51. Darkroom Safelights Kodak GBX filter Dark red
Low intensity (7-15 watts)
4 feet from work area
Direct illumination possible with most films

52. Darkroom Safelights Kodak Wratten Series 6B Orange-brown
Amber filter
Safe for films sensitive to blue/violet light

53. Darkroom Safelights Light emitting diode (LED) High initial cost
Long-lasting

54. Darkroom Safelights Too many can result in too much light intensity
Benches and flooring
Light coloring will increase light reflection
Makes it easier to locate film, etc.

55. Darkroom Entrances Single door Double interlocking doors
Revolving door
Light-proof maze

56. Darkroom Pass Boxes Exposed/unexposed compartments
Allow cassettes to be passed to and from darkroom
Prevent light from entering during process

57. Darkroom Ventilation
Chemical fumes must be vented to outside of building

58. Silver Recovery Systems
Feasible from financial standpoint
Prevents toxic heavy metal pollution in environment

59. Silver Recovery Systems
Must adhere to legislative acts:
Water Control Act of 1972
Hazardous Waste Act of 1976
Clean Water Act of 1984
Conservation and Recovery Act of 1986