Appearance
C-41 colour film development
This guide covers the step-by-step process of developing C-41 film. The process has five steps: develop, bleach, fix, wash and stabilise.
Bleach and fixer irritate skin, so wear gloves. The darkroom safety guide covers handling and disposal.
Before you start
Stand the chemistry bottles in the water bath until they reach temperature. Warm the loaded tank with a 1-minute rinse of water at the same temperature, so the cold tank does not cool the developer. The water comes out coloured. That is dye from the film's backing, and it is normal.
1. Develop
The first step is to develop the film, turning the latent image into a visible negative.
As with black & white film, this is done by converting the exposed silver halide crystals into metallic silver. The metallic silver absorbs light and appears black, creating a negative of the light areas of the scene.
How light affects density:
- Areas that received more light become denser with metallic silver.
- Areas that received no light remain as silver halides, which will be removed later.
In colour film, the dye couplers are built into the emulsion. As the developer works, it reacts with them to form a coloured dye next to each silver grain. The colour of this dye is the opposite of the colour of light that exposed the film.
How the dye colours form:
- Areas that received red light form cyan dye
- Areas that received green light form magenta dye
- Areas that received blue light form yellow dye
Through the combination of cyan, magenta and yellow dyes the colours and contrast of the image are formed.
INFO
While most film produces a colour negative when developed using the C-41 process, there are some notable exceptions. Ilford's XP2 Super film is developed using the C-41 process, but produces a black & white negative.
Development time & temperature
- Standard time: 3 minutes 15 seconds
- Required temperature: 37.8°C. Kodak's standard holds it within 0.15°C either way. Home kits often allow a little more, so follow your kit's sheet.
- Any variation in temperature or time can cause colour shifts
To prevent colour shifts, use a temperature-controlled water bath for the most consistent results. These can be made at home using a large sink basin, and a sous vide immersion circulator.
Kit chemistry can be reused for several rolls, with extra development time for each one. Your kit's sheet lists the times.
Agitation technique
Regular agitation ensures even development by moving fresh chemistry over the film surface.
Kits differ in how they want the tank agitated, by hand or in a rotary processor, and in whether the time changes. Follow the instructions for the kit you have.
2. Bleach
After development, the bleach converts metallic silver back into silver halides, allowing it to be removed in the fixing stage. This leaves only the colour dye clouds formed during development. Skipping the bleach step is a technique commonly referred to as bleach bypass.
Bleach time & temperature
- Standard time: 6 minutes
- Temperature: not as critical, but keeping it close to 38°C is ideal
- Agitation: Continuous or 10 seconds every 30 seconds
INFO
Some C-41 film developing kits come with a combined bleach and fix step, often labelled 'Blix'. Follow your kit's instructions.
3. Fix
Fixing removes unexposed silver halide crystals from the film, making the negative stable and light-safe.
Fix time & temperature
- Standard time: 6 minutes
- Temperature: not as critical, but keeping it close to 38°C is ideal
- Agitation: Continuous or 10 seconds every 30 seconds
If the clear areas still look milky after fixing, the film is under-fixed and can be fixed again. Colour negative film can appear slightly foggy when wet, so drying the film before deciding to re-fix might prevent doing so unnecessarily.
4. Wash
Wash the film before the stabiliser. See washing colour film.
5. Stabiliser
The stabiliser prevents colour shifts and fading over time. It contains chemicals that protect the dyes in the emulsion.
The stabiliser is the last step. Do not rinse after it: hang the film straight up to dry.
Stabiliser time & temperature
- Standard time: 1 minute
- Temperature: not as critical, but keeping it close to 38°C is ideal
- Agitation: Continuous or 10 seconds every 30 seconds