Film Processing (5) Flashcards Preview

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Flashcards in Film Processing (5) Deck (33)
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1
Q

Five steps of manual film processing:

A
  1. development
  2. stopping the development/pre-wash
  3. fixing
  4. washing
  5. drying
2
Q

Describe the Development process

A

Developing agent gives up electrons to convert silver halide grains to metallic silver.

  • exposed grains develop rapidly, with enough time convert silver ions to silver metal.
  • requires proper temp
3
Q

Chemicals that make up developer:

A
  • Metol and hydroquinone (convert silver halide to black metallic silver)
  • Sodium Carbonate (accelerate)
  • Sodium sulphate (preservative, reduce oxidation)
  • Potassium bromide or potassium iodide (ensure reduction of exposed grains only/restrainer)
  • wetting, softening and anti-swelling agents (improve developer quality and lifespan)
4
Q

The rate of development is affected by the ____ of the solution.

A

temperature of the solution.

- as temperature rises, rate of development increases

5
Q

What is the most common developer temperature?

A

20°C or 68°F

6
Q

How are temperatures maintained in manual tanks?

A

immersion heaters/chill-chasers or heating elements (coils) around tank exteriors

7
Q

What is the average concentration of liquid developer?

A

10 litres per 40 litre tank of clean water.

8
Q

How can we monitor the activity of a developer?

A

test films, exposed under standard conditions. densities of exposures are measured and compared to densities of original exposures to determine any noticeable loss of gain in chemical activity.

9
Q

A loss in developer activity would result in a ____ in density values.

A

reduction in density values.

Increase density = increased activity, decreased density = decreased activity.

10
Q

What is the frequency of agitation in developer?

A

5-10 seconds for every minute f development.

11
Q

What is the Stop Bath’s purpose?

A

Deactivate the developer in the emulsion before the film goes into the fixer bath.

12
Q

What is the stop bath mixture made of?

A

25ml glacial acetic acid per litre of clean water

13
Q

What is the purpose of Fixing?

A
  • Remove all undeveloped silver salt on the emulsion, leaving only the developed silver image.
  • harden gelatin for subsequent drying
14
Q

Define “clearing time”

A

time interval between fixing the film and the disappearance of the original yellow “milkiness”.
- fixer is dissolving undeveloped halide crystals

15
Q

Total fixing time should be longer than the clearing time by ____ to ___ times.

A

2 to 3 times

16
Q

What temperature should the fixer be held at?

A

18-24°C

17
Q

Clearing time checks: once clearing times begin to exceed ___ to ___ minutes the original clearing time, it is time to ___ the fixer bath.

A

10 to 12 minutes of the original clearing time, it is time to change the fixer bath.

18
Q

Fixing time and agitation time:

A

no longer than 15 minutes

agitate every 1-2 minutes

19
Q

Describe Clearing time checks

A

performed regularly

  • unexposed film in fixer solution and then observed .
  • time required to remove silver is recorded and minimum fixing time is established (2-3X clearing time)
20
Q

Fixer solution mix:

A

10L solution per 40L water filled tank

21
Q

Chemicals that make up fixer:

A
  • potassium alum (hardening agent)
  • organic acid (neutralizer)
  • sodium sulphate (preserve)
  • salt buffer
  • Hypo-clearing agent (solvent)
22
Q

Hourly rate of flow for a wash tank:

A

4-8x the volume of the wash tank

23
Q

What is the purpose of washing?

A

remove any remaining chemicals after the fixing

24
Q

Times and temperatures for washing

A

washed at minimum 20 minutes in non-circulated water (constant agitation required)

18-21° C not >25°C or <15°C

25
Q

What is the purpose of a wetting agent?

A

Reduce drying times and possibility of water marks.

done by reducing surface tension

26
Q

What is a wetting agent?

A

Photo-flow
also use jetdry or dish soap

100ml per 40L of water

27
Q

How long is film immersed in a wetting agent?

A

10 seconds prior to drying

28
Q

Describe the drying process:

A
  • dry warm (28-48°C)
  • do not prolong drying! can lead to brittleness, burns, melts
  • circulated air
  • built-in-fans, filters, heaters, desiccants
29
Q

Four steps of automatic film processing:

A
  1. development
  2. fixing
  3. washing
  4. drying
30
Q

Production time using an automatic film processor increase by:

A

10x

1.5 to 15 minutes

31
Q

Parts of an automatic processor:

A
  • feed system/tray
  • transport system
  • auto replenishment
  • temp control
  • agitation system
  • constant flow/wash system
  • high-flow air system
32
Q

Advantages of automatic processing

A
  • higher more consistent quality
  • increase production
  • no contact (reduced change of spillage)
  • requires less space
33
Q

Disadvantages of automatic processing

A
  • cost
  • long warm up time
  • maintenance
  • back up incase of failure