Evolution of Analog Photography and Film Development

History of Photographic Processes

• 1839 Daguerreotype: A metal surface covered with a layer of silver. The image is revealed by mercury vapors. It does not allow for copies.
• 1839 Calotype: A negative on wax paper. It allows for contact printing but has less definition than the daguerreotype.
• 1851 Wet Collodion: An emulsion of silver nitrate, cadmium bromide, water, and gelatin organized in collodion (a mixture of alcohol, gun cotton, and ether) on a glass surface. It must be prepared moments before the shot and processed immediately. It allows for short exposures.
• 1880 Dry Plate: Silver salts are agglutinated with gelatin. These were prepared well in advance and could be processed months after exposure. This allowed for industrial production.
• 1888 Kodak Film: A strip of paper coated with gelatin emulsion. After development, it is removed from the paper base to make copies.
• 1891 Transparent Film: The emulsion is fixed on a plastic base of nitrocellulose.

Loading Film into the Developing Tank

1. Cut the tongue of the film at right angles.
2. Smooth the edges and the center of the cut.
3. Insert the beginning of the film into the spiral reel.
4. Advance the film into the spiral through swinging movements.
5. Cut the film at the height of the spool to reach the end.
6. Insert the spiral into the light-tight tank and close the lid.

Film Development Procedure

1. Developer: Pour the developer (check temperature: 18-24°C). Cover the tank. Shake for the first minute continuously, then 10 seconds every minute. Empty the developer, leaving 10 seconds to meet the development time.
2. Stop Bath: Pour the stop bath (maintaining temperature). Cover the tank. Shake for 15 seconds. Empty the stop bath when 10 seconds remain to reach the total time (1 minute).
3. Fixer: Pour the fixer (maintaining temperature). Cover the tank. Shake for 10 seconds every minute. Empty the fixative, leaving 10 seconds to meet the total time (double the time it takes for the film to become transparent).
4. Rinse: Rinse with water for 30 to 60 seconds.
5. Neutralizing: Immerse in a thiosulfate neutralizing solution for 2-3 minutes (stirring every 30 seconds).
6. Wash: Wash in running water for 5 minutes (15 minutes if step 20 is skipped) with a flow of 5 liters/minute.
7. Final Rinse: Empty the tank and refill with distilled water and a wetting agent (2-3 minutes).
8. Drying and Archiving: Remove the film from the spiral and hang to dry. Once dry, cut the film into strips of six negatives and store in a negative archive.