3. Film processing involves a series of organized
procedures namely
Development.
Rinsing.
Fixing.
Washing.
Drying.
4. DEVELOPMENT
Development is a chemical process that produces
visible image from the latent image. The solution
used for this purpose is called developer.
The developer converts the exposed silver ion into
metallic silver, by reduction process (Ag+ + e– = Ag).
The developer provides the electrons to the
sensitivity center.
6. Hydroquinone, phenidone or metol are used as
developing agents
Hydroquinone slow acting and is responsible for
the black shades.
Phenidone acts rapidly and produce light gray .
7. Activator
Sodium carbonate and sodium hydroxide
serve as an activator, which swell gelatin,
produce alkalinity and control the pH.
8. Restrainer
Potassium bromide is used as
restrainer, which is a antifogging agent.
It decreases the fog, by protecting the
unexposed crystals.
9. Preservative
Sodium sulfite is used as preservative.
The preservative control the oxidation
of the developing agent, by air and other
components.
11. Sequestering
Chelates is used as sequestering agent,
which remove impurities (aluminum
ions) and soluble salts.
12. Rinsing
When the X-ray film is removed from the
developer, rinsing also partially stops the
reaction of the developer and neutralizes the
alkalinity of the residual developer.
13. FIXING
Fixing is the process of making the image
permanent without loss.
The solution that does the job is called fixer. It
removes the unexposed silver halides without
damaging the image, hardens the gelatin emulsion
and stops residual development.
15. Acetic acid is used as activator, which neutralizes the
developer and stops its action.
Sodium thiosulfate or ammonium thiosulfate salts
(Hypo) are used as fixing agents.
16. Hardener and Preservative
Potassium alum is used as hardener
which protects it from physical
damages.
Sodium sulfide is used as preservative
which maintains the chemical balance.
17. Buffer
Acetate is used as buffer, which keep
the pH of the fixer constant.
18. Sequestering solvent
Boric acid and boric salts are used as
sequestering agent, which removes metallic
ions, such as aluminum impurities.
19. WASHING
The film must be washed with water, to
remove fixing bath chemicals, otherwise, it
will change the black silver to brown silver
sulfide.
20. DRYING
The final step in processing is to dry the
radiograph. The film may be dried in dust
free open air area.
Hot air drying cabinets are also useful for
drying, which is equipped with a fan and
heating element to flow hot air.