Developer Chemicals in Photography

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Questions and Answers

What is the primary role of phenidone reducer in development?

  • To act as a restrainer
  • To build gray tones (correct)
  • To act as a preservative
  • To build blacks in the image

Which reducer is known for providing upper scale density?

  • MQ reducer
  • Hydroquinone reducer (correct)
  • PQ reducer
  • Elon/Metol reducer

What is the function of the buffer in the developing process?

  • To speed up development
  • To reduce surface tension
  • To hinder chemical oxidation
  • To maintain pH (correct)

What does an activator do in the development process?

<p>Facilitates swelling of gelatin (B)</p> Signup and view all the answers

What is the purpose of an anti-foggant in photographic development?

<p>To prevent chemical fog (B)</p> Signup and view all the answers

Which component acts to prevent rapid aerial oxidation?

<p>Preservative (B)</p> Signup and view all the answers

What does a bleacher usually contain to inhibit growth of fungi?

<p>Fungicides (A)</p> Signup and view all the answers

What is the role of a wetting agent in the development process?

<p>To stimulate uniform development (D)</p> Signup and view all the answers

Which reducer is characterized by providing intermediate density and is sensitive to light and temperature?

<p>Phenidone reducer (D)</p> Signup and view all the answers

What is the main benefit of using a carbonate buffer in photographic development?

<p>To maintain pH and provide an alkaline source (C)</p> Signup and view all the answers

Which chemical is added specifically to PQ developers to enhance their function?

<p>Benzothiosulfate (B)</p> Signup and view all the answers

Which component functions to control the activity of the reducers in the photographic development process?

<p>Regulator (A)</p> Signup and view all the answers

What role does the sodium sulfite play in photographic development?

<p>It serves as a preservative to prevent rapid oxidation (B)</p> Signup and view all the answers

Which chemical is primarily used as an anti-oxidant in photographic development?

<p>Glutaraldehyde (B)</p> Signup and view all the answers

What is the primary function of a hardener in the photographic development process?

<p>To make the emulsion more resistant to damage (D)</p> Signup and view all the answers

Which of the following is used to promote uniform development by reducing surface tension?

<p>Wetting agent (A)</p> Signup and view all the answers

Which chemical acts as a clearing agent by dissolving unexposed silver halide crystals?

<p>Sodium thiosulfate (B)</p> Signup and view all the answers

How does a replenisher differ from a standard developer solution?

<p>It is low in activator but high in reducers and preservatives (B)</p> Signup and view all the answers

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Study Notes

Developer Chemicals

  • Phenidone reducer:
    • Builds gray tones.
    • Provides intermediate density.
    • Sensitive to light and temperature.
    • Dmin = 1.2
  • Hydroquinone reducer:
    • Builds blacks.
    • Provides upper-scale density.
    • Sensitive to oxygen.
    • Dmax
  • Elon/Metol reducer:
    • Added to hydroquinone in manual processing.
  • PQ reducer:
    • Used for automatic processing.
    • 15x superadditivity than MQ.
  • MQ reducer:
    • Used for manual processing.
  • Carbonate buffer:
    • Maintains pH.
    • Source of alkali.
    • Can be either Na or K carbonate.
  • Accelerator:
    • Speeds up development.
    • Allows the reducers to attack the AgBr crystals after swelling.
    • Can be either Na or K hydroxide.
  • Activator:
    • Facilitates swelling of gelatin.
  • Alkalinizer:
    • Decreases and maintains the level of pH.
    • Provides the necessary alkaline medium due to the hydroxide.
  • Wetting agent:
    • Stimulates uniform development by reducing surface tension.
  • Restrainer:
    • Prevents overdevelopment.
    • Can be either K or Na bromide.
    • Can also be K or Na iodide.
  • Regulator:
    • Controls the activity of the reducers.
  • Anti-foggant:
    • Prevents chemical fog.
  • Starter solution:
    • Added only to a fresh developer solution.
  • Benzothiosulfate organic restrainer:
    • Added only to PQ developers.
  • Na sulfite:
    • Preservative.
    • Prevents rapid aerial oxidation.
  • Cycon:
    • Stabilizer.
    • Promotes equilibrium of chemicals.
  • Anti-oxidant:
    • Prevents rapid chemical oxidation.
    • Reacts with quinone, forming hydroquinone monosulfate.
  • Glutaraldehyde:
    • Hardener/tanning agent.
    • A weak hardener.
    • Prevents damage to the emulsion during transport.
  • Dialdehyde:
    • Hardener/tanning agent.
    • A weak hardener.
    • Prevents damage to the emulsion during transport.
  • Distilled water:
    • Solvent.
    • Dilutes and concentrates chemicals for proper strength.
  • EDTA:
    • Anti-sequestering agent.
    • Chelates/borate salts.
    • Prevents precipitation of aluminum and calcium.
    • Prevents sludge formation in the bottom of the tank.
  • Calgon:
    • Anti-sequestering agent.
    • Chelates/borate salts.
    • Prevents precipitation of aluminum and calcium.
    • Prevents sludge formation in the bottom of the tank.
  • Bleach (5% fungicides):
    • Inhibits the growth of fungi.
  • Anti-frothant:
    • Prevents bubble formation.
    • Prevents air oxidation.
  • Replenisher:
    • High in reducers, activators, and preservatives but without a restrainer.
    • Can return the chemical activity of the developer back to the original.
  • Bleach (6 ounces algaecide):
    • Added to the wash tank.
    • Inhibits algae growth.

Developer Chemicals Breakdown

  • Reducers:

    • Phenidone: builds gray tones, provides intermediate density, sensitive to light and temperature.
    • Hydroquinone: builds blacks, provides upper scale density, sensitive to oxygen.
    • Elon/Metol: added to hydroquinone in manual processing.
    • PQ: used for automatic processing, 15x superadditivity than MQ.
    • MQ: used for manual processing.
  • Buffer: maintains pH, source of alkali.

    • Carbonate: Na or K carbonate.
    • Boric Acid
  • Accelerator: speeds up the development process, allows the reducers to attack the AgBr crystals after swelling.

    • Na or K hydroxide
  • Activator: facilitates swelling of gelatin.

    • Alkalinizer: decreases and maintains level of pH, provides the necessary alkaline medium owing to the hydroxide.
  • Wetting Agent: stimulates uniform development by reducing surface tension.

  • Restrainer: prevents overdevelopment.

    • K or Na bromide
    • K or Na iodide
  • Regulator: Controls the activity of the reducers.

  • Anti-Foggant: Prevents chemical fog.

  • Starter Solution: added only to a fresh developer solution.

  • Benzothiosulfate Organic Restrainer: added only to PQ developer.

  • Preservative: Prevents rapid aerial oxidation.

    • Na sulfite
    • Cycon
  • Stabilizer: promotes equilibrium of chemicals.

  • Anti-oxidant: prevents rapid chemical oxidation, reacts with quinone, forming hydroquinone monosulfate.

  • Hardener/Tanning Agent: a weak hardener, prevents damage to the emulsion during transport.

    • Glutaraldehyde
    • Dialdehyde
  • Solvent: dilutes and concentrates the chemicals for proper strength.

    • Distilled water
  • Anti-Sequestering Agent: an oily substance that prevents precipitation of aluminum and calcium, forms a sludge at the bottom of the tank.

    • EDTA
    • Chelates/Borate salts
    • Calgon
  • Bleach 5% Fungicides: inhibits growth of fungi.

  • Anti-Frothant: Prevents bubble formation and aerial oxidation.

  • Replenisher: High in reducers, activator and preservative but w/o restrainer, can return the chemical activity to the original.

Stop Bath Chemicals

  • Acidifier: provides the necessary acid medium.

    • Acetic acid
    • Sulfuric acid
  • Neutralizer: neutralizes the developer and stops the development action.

    • Acetic acid

Fixer Chemicals

  • Clearing Agent: dissolves and clears away unexposed silver halide crystals (pH 4.2 to 4.9)

    • Ammonium thiosulfate
    • Na thiosulfate
  • Fixing Agent: permanently fixes the image.

  • Hardener: shrinks and hardens the emulsion.

    • K alum
    • Chrome alum
    • Al Chloride
  • Tanning Agent: increases temperature at which the gelatin softens.

    • Chrome alum
  • Permanenting Agent: permanently fixes the image.

  • Preservative: prevents deterioration of chemicals and helps maintain chemical balance.

    • Na or K sulfite
    • Cycon
  • Anti-oxidant: prevents internal and external oxidation.

  • Stabilizer: maintains the equilibrium of the chemical in the solution.

  • Solvent:

    • Distilled water
  • Sequestering Agent: an anti-sludging agent which delays precipitation of Al hydroxide (alkaline) by increasing pH.

    • Borate salts
  • Hyponeutralizer: solution used between fixing stage and the final washing cycle to decrease the washing time of the film to prevent hyporetention.

    • Acetic acid, silver nitrate and solvent

Other Processing Chemicals

  • Hypokit: a chemical used to determine the presence of thiosulfate on processed films.
  • Bleach 6 ounces algaecide: added to the wash tan.

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