All 35mm film processing techniques are done in a dark room.
Building your own dark room at home is a great way to have control over how your film is processed. All processes of developing 35mm film involve submerging the film in a series of chemical baths. The 35mm film developing process you use is determined by what type of film you are using and what outcome you want.
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When you take a photograph, the shutter of the camera opens for a split second to allow light to penetrate the film within the camera. This light creates a latent image on the film, which the film processing technique then turns into a positive image and makes the film insensitive to light to prevent further exposure. Black and white and color film comes in reversal and negative options. Reversal film creates a positive image on the film when it is developed, creating a slide, while negative film creates a reverse image on the film so that it can be printed onto photo paper.
Black and White Negative Processing
Black and white negative processing is one of the most simple 35mm processing techniques and is taught in beginning photography classes. The film is removed from its spool and placed in a developing container in a dark room. The film is then subjected to the chemical bath process. First the developer is poured into the container to transform the silver gelatin layer into an image. Next the stop bath is added to cease the development process. The film is then rinsed with water or a fixer. The negatives are hung up to dry, cut and then placed in an enlarger to make prints.
Color Negative Processing
Most color 35mm film is processed using the C-41 technique, whether it is processed in a dark room or by a commercial developer. The C-41 begins like the black and white negative technique with placing the film in a developing canister. Developer is then added to the canister, but unlike the black and white developer, the color chemical has byproducts that activate the color dyes to create a color image. The film is then washed in a bleach which functions as a stop bath for the color and negative developing. It is then washed in fixer, then water, and is then hung up to dry.
Reversal Processing
The black and white reversal processing technique follows the same initial steps as the negative processing technique. However, after the stop bath, a bleach is added to the developing canister to remove the negative image, leaving only a latent positive image. The film is then fogged chemically, exposing a positive image, and then processed again using the developer, stop bath and fixer. A similar technique is employed for developing color film. This is called the E-6 process, as it generally contains six steps: developer, stop bath, reversal bath, color developer, bleach bath and finally a fixer bath.
Tags: image film, stop bath, dark room, film then, positive image