C-41

The discontinued Kodak Professional BW400CN chromogenic black and white film

C-41 is a standardized process in chemical (analog) photography for the chromogenic development of negative films . The name comes from the inventor of this process, Kodak ; other companies such as Agfa , Tetenal or Fujifilm offer functionally equivalent negative development processes under different names. At Agfa, for example, the process was referred to as AP 70 .

All current color negative films are now developed using the C-41 process ( reversal films for slides, however, require other processes such as E-6 ). Some chromogenic black and white films (such as the XP2 or XP2-super from Ilford and the Kodak BW400CN, which is no longer in production ) can also be processed in the C-41 process and thus also in the rapid development laboratory.

processing

The development of color negative films is standardized; H. Different photosensitive films and films from different manufacturers have the same development time. However, chemicals are used up faster with films that are more sensitive to light. The process of the C-41 process is similar to developing black and white films.

The original process is divided into the following steps:

1. Develop
2. (Stop bath)
3. bleaching
4. Water
5. Fix
6. Final waters
7. Stabilizing bath

The chemistry sets available on the market are mostly designed for a shortened process:

1. Develop
2. (Stop bath)
3. Bleach-fix
4. Final waters
5. Stabilizing bath

The developing bath is originally specified for a temperature of 100.0 ± 0.25 ° F; Kodak specifies 37.8 ± 0.15 ° C for the Celsius scale; In the meantime, however, there are chemical sets with which color negatives can be developed manually at 30 ° Celsius in the developing container with greater temperature fluctuations. The bleach-fix bath (blix) must be at the same temperature as the developer, but the other steps are relatively insensitive to temperature and require a temperature of around 24 to 40 degrees Celsius.

variants

There are still modifications of the standard process, such as C-41 BNP (Agfa: AP 71) and C-41 RA NP (Agfa: AP 72), which are tailored to modern films and allow a shorter processing time.

Web links

• The process C-41 - detailed description by Christoph Caspari
• Developing color negatives with Tetenal Colortec C-41 - Developing color negative film at home with C41.

Individual evidence

1. ↑ KODAK FLEXICOLOR CHEMICALS. Accessed February 28, 2019 . 
2. ↑ Agfa: Technical data sheet C-7172-D7 ( Memento from April 18, 2003 in the Internet Archive ).