RAD 254 Chapter 12 Processing the Film Latent Image Basics/Dates Universal time and temp: 5 min at 68 degrees F Each MAJOR step is 2X longer than the previous

1942 = First “Automatic Processor by Pako (some 20 ft. long and required film to be placed on hanger racks for transport) 1956 = First “roller” transport processor by Kodak (5 minute) 1965 = First 90 sec processor by Kodak 1987 = First 45/90 sec variable processor by Konica

Development: conversion of latent image to manifest image (black metallic silver) Fixation –Removes the UNEXPOSED silver halide crystals –Preserves the image

Automatic Processor (90 sec) Items of importance Time for devel and fix = 22 seconds for each Developing agents: Hydroquinone, phenidone/metol/elan Fixing agents: Acetic acid, ammonium thiosulfate

Developing agents Hydroquinone – SLOW acting build up of “blackest blacks” (also known as the reducing agent) Phenidone/metol/elan – act RAPIDLY to build up GRAYS Buffering agents (to maintain alkalinity) – sodium carbonate/sodium hydroxide (Lye) Restrainers – “Potass”ium bromide/iodide – prevents developer from converting the UNEXPOSED silver halide to black metallic silver

Devel. Cont. Preservative – sodium sulfite Hardener – Gluteraldehyde (others used: potassium alum, aluminum chloride, chromium alum

Fixing Agents Same hardener and preservatives as devel. Acetic acid – activator – stops action of developer Ammonium thiosulfate – FIXING AGENT Acetate – “Buffering agent” – helps maintain proper pH

Washing Universal solvent = Water “Hypo retention” residual chemicals on the film = turning the film brown over time –MUST BE CHECKED FOR MAMMO

Automatic Processing Six total systems –Transport –Temperature –Circulation –Replenishment –Dryer –Electrical

Transport Rollers and transport “racks”, drive gears –TRANSPORT ROLLERS are 1” in diameter (3.14” circum.) “Pi lines” are a common artifact –“Guide shoes” also can cause artifacts (especially with new processors and racks) –Cross over rollers –Time guidelines +-2 percent of required time

5 “other” systems Temperature – proper temps. For developer, wash and dryer Circulation – agitates chemicals, FILTERS DEVELOPER Replenishment – meters and replaces chemistry Dryer – Dries film (know diff. between wet and “tacky” Electrical – All electrical areas

Special Processing Daylight – Enables one to place a cassette in the daylight processor and the processor opens/processes/reloads cassette Dry Processing: –Photothermic – Used laser to form a latent image and HEAT to make it visible –Thermographic – Uses heat to DIRECTLY produce the image