Fixer

Fixer

Write a short note on fixer.
Answer.

Fixer

• The primary function of fixer is to dissolve and remove the undeveloped silver halide crystals from emulsion and harden the emulsion.
• This creates white or clear areas on the dental radiography.
• The presence of unexposed crystals causes film to opaque.
• If the unexposed crystals are not removed the image on the resultant radiograph is dark and non-diagnostic.
• A second function of the fixer solution is to harden and shrink the film emulsion.
• The fixing solution also contain five components, all dissolve in water.
  • Clearing agent
  • Acidifier
  • Preservative
  • Hardening agent
  • Solvent (water)

“Understanding the role of fixer in developing X-ray films: Q&A explained”

Fixer Clearing agent

• It is also known as fixing agent.
• It consists of sodium thiosulphate or ammonium thiosulphate.
• Purposeoftheclearingagentistoremoveorclearunexposed as well as undeveloped silver halide crystals from film emulsion which allow light to pass through film image and permit viewing of radiographic image on the view box.
• Clearing agent clears the film so the black image produced due to the developer should be distinguished.

“Importance of studying fixer solutions for better image quality: Questions explained”

Fixer Preservative

• Sodium sulphite is used as a preservative.
• It causes prevention of chemical degradation of the fixing agent.
• It also helps in clearing of the film by binding to the oxidized developer which is carried to fixing solution.

Fixer Hardening Agent

• Ammonium sulfate/potassium aluminum is used as a hardening agent.
• It leads to the shrinkage as well as hardening of the gelatin in the film emulsion to prevent the oxidation of gelatin and provide protection to it against the scratches.
• This agent also shortens the drying time by reducing the swelling of emulsion at the time of final wash which causes less mechanical damage to emulsion and limit the water resorption.
• If any contaminated alkali from developer is present, it neutralizes it.

“Common challenges in using fixer effectively in radiography: FAQs provided”

Fixer Acidifier

• Here the acidifier used is acetic acid or sulphuric acid.
• Acidifier neutralizes the alkaline developer.
• Acidifier provides necessary acidic medium for diffusion of thiosulphate in emulsion.
• It also provides the acidic environment which is needed by fixing agent.

Fixer Solvent

Water is used as a solvent.