تحميض الورق الحساس الأبيض وأسود .. كتاب فن التحميض والطبع والتكبير

Fourth: developing white and black sensitive paper

As with films, exposing photosensitive paper to the light of a magnifier creates a latent image that can be shown and fixed by acidifying solutions. The best results are those obtained by following the instructions of the photosensitive paper producer. In the absence of instructions, we recommend the use of solutions dedicated to the development of paper
The sensor, although the film development solutions will also work, and see the chapter on chemicals).

Here we emphasize the importance of both temperature and acidification time.

The temperature of acidifying solutions, especially the show solution.

1

This factor affects not only the development times, but also the intensity and colors of the image. When the solutions are cold, they will work slowly and unevenly, resulting in an image that appears underexposed, where the areas of light are chalky and the areas of shadows are grey.

B - Display times: In order to obtain the richest and most fertile color gradations in the image, it must be displayed in a time of not less than a minute and not more than two minutes. As for the image that appears to be fully visible before this time, or that is not shown except after a longer period of time, these are images that have not been well-exposed with the magnifier, and that will appear on them! Therefore, a good exposure is required in order to be exposed during this time, assuming that the solutions are fresh and have not been exhausted or spoiled after that. The white and black papers are developed using the following steps:

1- Preparation of tanks and chemicals:

And you must put them in order according to the order of work, the appearance, then the stand, then the fixture, then the washing basin.” Prepare the solutions so that their temperature is slightly higher than the required temperature, so that once the magnification is over, the solutions will have reached a temperature of 20 °C, which is the temperature usually used in developing black and white. Bottles of solutions can be placed in a warm water bath until work begins. After pouring the solutions into the basins, you can raise or lower the temperature of the solution.
By placing bottles of hot water or cold water in the solution, and thus do not change

From its installation prepare the timer. 2- Exposing the sensitive paper to the light, whether it is in the magnifier or of course the contact. This has already been explained

Display: (in complete darkness)

Always try not to touch the sensitive surface of the paper except from the edges, and make the paper slide in the basin showing its edge with a soft, non-nervous movement until the solution submerges it (the sensitive surface is upwards. Move the paper inside the solution constantly, either by raising and lowering one of the sides of the basin and be careful not to spill the solution) or by moving the paper Inside the tub by holding sensitive paper dried. And do not dip your fingers in the solutions so as not to contaminate your fingers and transfer this pollution to all the solutions, which spoils them, which causes the appearance of yellow and brown spots in the image. I always use different grips for the display basin and the fixation basin. Keep stirring for the entire time it takes to buff (one and a half to two minutes). When buffing is finished, lift the image (by grasping peat) from its end over the buffing basin for several seconds until most of the buffing solution drops out of it, then transfer it to the stopping basin.

See Appendix 8 for the number of photos you can develop in solution

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4- Suspension:

Dip the image in the stop solution in the same way, and be careful not to contaminate the grip pad with the stop solution. Return the grip pad to the display basin. Move the image continuously in the stop solution for 10 seconds, then remove it in the same way using the grip pad in the fixation basin.
The stopping solution not only stops the display process immediately, but also prevents contamination of the fixing solution with the appearance, and spots often occur in the image as a result of transferring it directly from the display to the fixer. Therefore, if you do not have a stopping solution, nothing less than washing the image with water before transferring it to the fixation basin. Fixation:

Dip the image into the fixation solution in the same way, i.e. by sliding its edge into the solution (this method prevents the gathering of air bubbles on the sensitive surface, then actively move the image into the solution for ten seconds. Fixation usually takes 5 to 10 minutes depending on the degree of activity of the solution. In the meantime Every 1-2 minutes, move the sensitive paper and pull it apart until it is firmly seated.

Excessive retention of the image in the fixing solution leads to whitening of the image, and may lead to the appearance of yellow spots on the appearance of sensitive paper. And if you want to install the image perfectly, you can put it in two installation basins, one after the other. And when the first solution is exhausted, replace it with the second and put a new solution. Of course, the fixation period in the two basins should not exceed 10 minutes. After the image remains in the fixing solution for a minute, you can turn on the light in the room to examine the image, then turn the image over on its face in the fixing solution and leave it for the rest of the specified time, then remove the image using a dry cloth to the wash basin. 6 - Washing:

It is important to wash very well for the durability of the image to get rid of the remnants of all silver salts. And the survival of these salts will lead in the long term to the appearance of spots in the images and their gradual disappearance, and this is likely to happen more if the image is fixed in a strong or exhausted fixation solution! Or left the pictures in it for a long time. The pictures are washed in running water for the following periods:
60 minutes for thick paper DW.

30 minutes for thin paper - .

15 minutes for RC resin paper.

The water source must come from the bottom of the wash basin and the water should leak from the top of the basin in order to get rid of all the chemicals that are usually at the bottom. There are some siphon devices installed on the wash basin to do this, or the water hose can be placed at the bottom holding an iron clip, and we make the water leak on the edge of the basin.

In the event that running water is not available, put the pictures in a deep basin of clean water and change the water every five minutes until the washing period is over. The pictures must be moved inside the wash basin every once in a while, separating the pictures

each other.

7- Drying:

Lift the picture from the wash basin, holding it by one end, and keep it over the basin for a while until the water falls from it. Prepare a smooth, clean surface, such as a sheet of clear glass or a sheet of wood covered with Formica, and prop it up against the wall so that it is at an angle with the horizontal. Place the photo on this surface and gently wipe both sides of the photo with the area of ​​the photo until you remove as much as possible. water . After this treatment, we find that the image has become wet or dewy only. Hang it from one of its corners with a clip in a dust-free place until it dries completely. from
Final notes:

1- Start the timer as soon as the paper is placed in the solution. 2- A safety light can be used at a height of 120 cm from the place of the basins. - Make sure that the solutions are not exhausted before starting work. With regard to the display solution, it is preferable to start work with a new solution. As for the rest of the solutions, make sure that they are not exhausted by using blue litmus paper in the case of the suspension solution and blotting paper in the case of the fixing solution, as previously mentioned (see the chapter on chemicals).