إظهار الأسود والأبيض .. كيف تعالج الصور .. كتاب التصوير الضوئي

Black and white development .. How to process images .. Book of photography

How to process images
Black and white development

The film that has been exposed to light remains sensitive to light even after the photographic machine, it is opaque and does not carry any visible image, its exit from. During the processing that includes several chemical baths, the undeveloped image appears and loses all sensitivity to light to become a transparent negative draft. Development is carried out in complete darkness because films are sensitive to the slightest light. The simplest way to process the film is to use a sealed bath that is not exposed to light called (a daylight development bath). In the darkness of a black room, it is sufficient to place the film in a screw that in turn enters the bath that is carefully closed by the cover until the rest of the processes are carried out in the light. As for the chemical solutions for the treatment, they enter and exit the cover through a sealed opening.

The first bath or bath for treatment is the developer: a solution composed of several: chemicals that are designed to work properly at a specific temperature, usually 20 ° C. The development affects the sections of the film affected by and unaffected by light, but more quickly on the affected sections. In fact, it is the exposure to light that determines the speed at which the silver halogen is converted into metallic silver: the image develops first. However, it must be understood that if the development time is prolonged, a general haze appears in the image. The manufacturer's instructions regarding temperature and development time must therefore be adhered to.

The second stage of film processing is carried out in a development stop bath. After the development time has expired, pour the developer out of the bath and replace it with this solution.

This bath consists of a medium acidity solution that stops the action of the alkaline developer. This bath not only allows a limited development time, but also prevents the alkaline solution from reacting with the next solution, which is the fixing bath.

After the development and the stopping bath, the film remains sensitive to light and opaque, but the negative can be seen. The fixing solution will convert the silver halogens into a water-soluble salt: this salt will be removed by washing the film under running water in half an hour. The treated film is then squeezed as gently as possible with a squeezer equipped with a double sponge. All that remains is to hang the film with the squeezer in a quiet, dust-free place where it will dry. When the film is dry, it is cut into batches - usually 6 35mm films and 3 6x6cm films. These batches are placed in a protective envelope.

- Developing materials:
To develop films in the best conditions, it is necessary to have a complete set of special equipment. It is necessary to be able to control the temperature and the time with great precision, thanks to a precise thermometer and a clock (timer). When the bath is filled in the dark, the film can be processed in full light. The solutions prepared for treatment must be kept at a constant temperature (20°) Celsius by immersing them in a water bath. Among the other necessary pieces are the small graduated basin for measuring volumes and the funnel that helps to pour solutions and liquids easily into the basin and bottles. The rubber tube to connect the tap to the basin during washing and tongs to hang the film and scissors.

- Filling a plastic screw with 35-flag film

Cut the beginning of the film in complete darkness, then open the cartridge and pull the film roll from it.

Give an alternating rotation movement to the two faces of the roll until the film enters the single-screw.

Hold the film by its ends so as not to leave fingerprints on it and insert it into the screw inlet slots.

Align the film passage slots in the screw grooves so that the reel faces are above them.

When the film is in, cut or tear the end of the film and pull the roll and then place the filled screw in the basin.

- Filling a 120 gauge film into a reel in a standard screw with a guide.

Set up the film filling machine in the dark. Remove the film protection paper.

Insert the end of the film into the filler and insert it into the center of the metal screw.

Wrap the film in the screw grooves.

When almost all the film is in the screw, remove the film protection paper and continue feeding the film.

Remove the screw from the filler and place it in the sealed tub.

- Processing the negative draft
When the film is in the tub and after the sealed lid is in place, you can turn on the light. Before starting to process the film, make sure that all the necessary elements are ready for the various stages. Follow the manufacturer's instructions regarding processing times.

The process of immersing the film in water before applying the reagent and adding the wetting agent before thinning (this prevents limescale deposits) is not necessary, but we recommend that you carry out these operations if you want to obtain a homogeneous processing and regular drying of the film.

After turning on the light, immerse the sealed basin in a container of 20°C water to keep the solution at a constant temperature.

Pour the developer quickly at 20°C into the basin and stir a little to expel air bubbles. Start counting the time and then close the basin.

During development, move the developer every half a minute either by shaking the basin or by using the rod placed in the center of the basin.

When the development time is over, pour the developer into a bottle for later use.

Pour the stop solution into the basin, then shake the basin and leave it for one minute to stop the development.

Then pour the fixative. Shake the basin every minute for the required time. Finally, empty the fixative into a bottle.

Remove the lid of the basin and connect the center of the basin to the water tap by means of a rubber tube. Wash the film according to the instructions given.

Hang the film from the bottom with forceps: remove excess water with sponge forceps and let it dry.

Record on the various bottles the date of use and the number of films processed. To reuse the solutions, follow the manufacturer's instructions.

When the film is dry, cut the negative draft, remove the dust from it and place the clichés in a protective envelope.