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Some other additions to the installation of display solutions:

Some show solutions may contain other chemicals that perform different functions than what we have mentioned above. Here is an example:

a) Solvents of Silver Salts such as Potassium Thiocyanate. Thiocyanate or Hypo (known chemically as Sodium Thiosulphate), and the previous salts are sometimes added to display solutions that lead to Fine Grain developers to dissolve part of the silver bromide salts deposited in gelatin. The amount of sodium sulfite may sometimes be increased in these solutions in order to perform the same purpose as above.

b) Substances that have no effect on the chemical process that results in the appearance of the image:

But it helps us to obtain clear negatives that are completely transparent, such as Sodium Hexametaphosphate, known commercially as Calgon, which would prevent any sediment from occurring on the transparent image if the water used in preparing solutions or washing was hard water or mineral (i.e. more than It contains the percentage of some salts such as calcium carbonate - sometimes in wells). Although these sediments likely to fall on the surface of the film do not have any chemical effect that harms the display process, yet it may stand as a barrier that prevents the effect of the solution from having an equal effect on all parts of the film surface, and the result appears as irregular, light-colored spots on the negative.

(C) Wetting Agents

If a sensitive film or glass plate is dipped in a container of water and then taken out directly, the water does not stick to the entire surface of the film or spread over it completely evenly. Rather, we find traces of water on scattered parts of its surface, and this is due to a property of liquids known as “surface tension.” Tension » It is the property that results in the impossibility of spreading the liquids on the surfaces that touch them evenly, and thus prevents their wetness evenly as well. Therefore, materials known as agents are used, sometimes as “wetting solutions”, and they reduce the ability of liquids to aggregate, and help them spread in a completely uniform and even manner on all parts of the film’s surface. This is of great importance when using very fast showing solutions that complete Showing in part of one minute (between 10-45 seconds, for example). These solutions are also useful in preventing the accumulation of air bubbles on the surface of the film during the display process.

D) Developer Improvers:

It is a group of organic substances sometimes added to the presenting solution, either instead of the inhibitor Retrainer (potassium bromide), or in addition to it.
Below we mention the names of some of the materials that are used for this purpose.

(a) Benzotriazole

(b) 6-Nitrobenzimidiazol

(c) 3:5-Dichloro-2-Aminopyridine

These materials can be obtained in the form of salts or in the form of prepared solutions produced by various factories. These materials have a very great ability to prevent fog, including the fog resulting from the long period of storage of sensitive films, by placing them in the solution in very small quantities less than ... Normally - less than 1 gram per liter of solution.
The appearance enhancers do not harm the properties of the salts that make up the appearance solution. The previous substances are also used in solutions to show positive images, where the amount of potassium bromide is intentionally reduced in the solution (3) so that the color of the image tends to black tone and where there is fear of the appearance of chemical fog - as a result of a deficiency of potassium bromide. Therefore, any of the previous materials is added to the solution.

Agents regulating the degree of acidity or alkalinity of the buffering agent:

If we add a weakly alkaline salt to a highly alkaline solution, or a weakly acidic salt to a highly acidic solution, the inevitable result is that the alkalinity or pH of the solution decreases. This process is known as buffering. It is hoped that alkalinity can be used as a means to control the degree of acidity or alkalinity of solutions.
And the factors regulating the expression are a group of salts that compensate for the change that occurs to the Barnaki machine, whether the degree of alkalinity or acidity of the display solution is, resulting from the chemical reactions that result from the reduction process. Sodium Carbonate, Sod Carbonate or Sodium Metaborate. Metaborate or Sodium Phosphate. The addition is at a fixed rate.

Among the regulating factors are buffering agents, which are sometimes added to reduce the activity of the presenting solution intentionally: such as adding boric acid in certain proportions to the exposure tank in machines showing feature films, as it is known that these machines are run by a motor that runs at a constant speed, and it must be proportional to The duration of the show with the duration of the installation and with the speed of rotation of the motor.

It is assumed that experiments have proven that the film must be shown for a period of eight minutes in a specific appearance solution in order for the degree of contrast to reach the required praise, and assuming that the fixation process requires that the film cycle be completed within the fixation tanks for ten minutes, then it would be wrong to increase the display time while the presenting solution remains. With the same degree of previous activity, (because of the consequent increase in intensity and contrast from the required limit). The activity of the solution shown by adding an acidic substance such as boric acid » at a certain rate, and this is what allows to increase the period of manifestation to. Ten minutes, for example. Thus, the function of boric acid in this case can be described as having reduced the degree of activity of the apparent solution to suit the period required for fixation.
For example, bleaching solutions that carry salts to regulate bleaching, Kodak bleaching solution No. 76. (And we will talk about its composition in connection with highlighting solutions that lead to fine granules)