The Evolution of Safe Lights in Photography: Understanding Film and Darkroom Practices

Photography has a rich history, from early black and white (BW) negatives to the vibrant colors of modern color films. One aspect of this history that is often fascinating and misunderstood is the use of safe lights in darkrooms. These lights play a crucial role in the entire development process, ensuring that sensitive materials are not exposed to harmful light. Let's explore why red lights used to be suitable for BW films but no longer work for color films.

Introduction to Safe Lights

In the early days of photography, particularly in the development of black and white films, it was necessary to use safe lights in darkrooms. These lights were designed to be non-toxic to the emulsions used in these films. During the process, these films had varying sensitivities to different colors of light. For instance, they were not very sensitive to red light, making it possible to use dim red lights during the development process to preserve visibility in the darkroom while protecting the film.

Evolution of Film Technology

As photography evolved, so did the technology behind film. BW films continued to use the property of selective sensitivity, allowing the use of red safe lights. However, when color photography was introduced, the technologies used changed dramatically. Color films and papers are highly sensitive to a wide range of wavelengths, which means that even low-intensity safe lights can still expose them to light and cause fogging.

In the early days of color photography, it was not uncommon to have no suitable safe light for BW film. While yellow or amber safe lights became standard for BW prints, these could still be harmful to color films. Today, almost all colors of light, including red, need to be completely eliminated from the darkroom to prevent exposure of color negatives.

Techniques for Using Safe Lights

To use safe lights effectively in a darkroom, photographers must understand the sensitivities of their film and paper. Different films and papers were designed with various sensitivities to different colors of light. For example, Low-pressure sodium lights, when used with a suitable filter, can provide very high visual acuity even if they do not expose certain types of film or paper. Kodak, Agfa, and Ilford sold numerous different safe light colors for specific purposes, including a very dark green one that was useful for certain panchromatic films.

When developing color negatives, it is essential to keep the darkroom completely dark. This can be achieved using blackout curtains and ensuring that even the smallest amount of stray light does not reach the sensitive materials. Even dimmer safe lights can expose color negatives, causing fogging and rendering the film unusable.

Conclusion: The Significance of Safe Lights

In conclusion, the use of safe lights in photography is vital for maintaining the integrity of the film and paper during the development process. While red lights were once perfectly safe for BW films, they cannot be used for color films due to their sensitivity to a wide range of light. Photographers must be aware of these sensitivities and take appropriate precautions to ensure the quality and usability of their negatives.