التحميض والطبع والتكبير .. كتاب التصوير علم وفن

Chapter V

Developing, printing and enlarging

Sooner or later, a day will come when the photographer will think of acidifying, printing, and enlarging that much, much more can be done without resorting to the extraordinary facilities of the laboratory. Although he resists.

In view of the size of this book and the enormity of this topic, we will pass through it quickly and take a quick look at it, which gives a quick and very brief idea, although at the same time it is not disturbing.

Perhaps the honorable reader has noticed that I did not show in this book any image that would require any special modification in the laboratory. All of them were developed and printed routinely in one of the automatic laboratories, and every modification was made inside the camera by installing a filter, or shooting several pictures on one negative, or re-photographing one of the pictures in a special way, etc. This is because I realize that creating a lab, especially for colors, is beyond the capabilities of most amateurs

Developing: It is customary to name the chemical treatment of the film to show the image and fix it under the name of developing. Image show theory:

When the film is exposed to light, the silver salts partially dissolve and form what is called the latent image. In order for this image to appear, a process must be performed.
Show image. This is a chemical process for silver reduction, whereby electrons are transferred from the backing solution to the silver halogens, and the silver is deposited in the form of black granules. These required electrons come from some organic substances with an aromatic ring, such as hydroquinone, methyl, etc. The reduction process is aided by the presence of an alkali, which facilitates the hydrolysis of the acidic hydroxyl group. Therefore, an alkaline substance such as sodium carbonate is added to the solution. Sodium sulfite is added to prevent the hydroquinone from interacting with atmospheric oxygen and to remove the hydroquinone oxidation products (i.e. it acts as a preservative). It is noted that the show substance works on all silver halogens that have been exposed to light and those that have not been exposed - but its effect on the halogens that have been exposed to light is faster and stronger, and therefore if the film is left in the show solution for a longer period than prescribed, we find that the whole film has become foggy, and if left for a longer period it becomes whole. Therefore, some bromide salts are added to delay the transformation of silver halogens that have not been exposed to light. The following is the composition of one of the most famous display chemicals, which is Kodak 72 D. It is suitable for displaying negatives and white and black sensitive papers.

1- Pack the film in complete darkness in a special developing container, then pour it into the container. (The light can be turned on after closing the box). Move the roller inside the case continuously first and then at regular intervals. The appearance

Acid for the time and temperature suggested by the film maker.
- Pour out the applicator after the specified time has expired, filling the can with clean water or acid solution to increase the hardness of the film backing.

Pour out the wash water

Fill the canister with stabilizer

- Hold for the specified time and then pour the fixative (the fixative can be reused several times

times) Wash with running water for at least an hour. Wash one last time by adding a gelling agent to prevent staining). Wipe off the excess water from the film.

12 Hang the film to dry in a place away from dus .