محاليل تجديد نشاط المحلول المظهر .. كتاب التحميض والطبع والتكبير

SOLUTION REPLENISHING LOOK LOOKING REPLENISHERS

Since it is always necessary for the degree of activity of the display process to remain regular at a constant rate, and equal among all the films that are shown in this solution, whether the film is the first in the order of display or the last, and this is a matter of great importance, especially in the process of showing long cinematic films, In order for the degree of density and contrast to be equal between the first parts of a movie and the last parts of it, it was necessary to search for means to achieve this end. It may seem at first glance that the greater the number of films shown in the solution, or the longer their lengths, a constant level of intensity can be maintained for recitation and contrast if the duration of display is increased at a constant rate. Flat films, glass panels, or even a large number of short, rolled films, but they do not achieve this purpose in the case of showing long cinematic films by automatic means in which the films are run at a constant speed between the different display tanks.
Therefore, special solutions are prepared to reactivate the presenting solution (Replenishers). They are added to it regularly, at fixed intervals, and in gradually small quantities, and in an amount equal to the degree of exhaustion.
The reactivation solution is added at a rate of 15-35 cm to all of the presenting solution, after showing an area of ​​450 cm of film (equivalent to one roll of 6×9 cm or 35 mm 36 film) and in many cases, the quantity depends on The additive of the activator solution is to compensate for the decrease in the quantity of the developer solution that was lost during the display process. If the added amount of the activator is not sufficient to compensate for this deficiency, the tank should be supplied with another quantity of a new developer solution, so that the level of the developer solution in the tank becomes constant. On the contrary, if it becomes clear to us that the presenting solution in the tank has not lost a large part of its quantity, so that it is not possible to add the required amount of the activating solution, then it is necessary to withdraw a quantity of the used presenting solution, so that it is easy to add the necessary amount of the activating solution. It is likely that the solution will flow and drain from the tank nozzle.

Composition of reactivation solutions

It also seems at first glance that adding specific quantities of a concentrated appearance solution of the same type as the exhausted appearance solution being used is the acceptable natural means to renew the activity of the last solution, but it becomes clear to us that this idea is wrong when we know that some of the materials included in the composition of the appearance solution have the ability to resist Rapid deterioration, and some of them do not have the same ability, so it is imperative that the reactivated solution carry salts that deteriorate quickly during exposure in proportions that exceed the proportions of other substances.
Although the reducing agents and alkalis gradually weaken their effect during the display processes, and the degree of concentration of the active residue decreases, on the other hand, we find that the amount of potassium bromide increases gradually in the solution as a result of the chemical reactions that take place during the display.
In sum, the rejuvenating solution must differ in its formulation, in order to quell the painful will, in one way or another, from the composition of the original appearance solution. The following rules are often observed in the composition of the reactivated solution:

a) For the cofactor:

The percentage of the reducing agent shall be increased by more than one or two times its quantity in the composition of the appearance solution with which we are working.

b) For the preservative:

The amount of sodium sulfite in the original solution is almost equal to its amount in the activated solution.

c) For alkaline substances:
If the alkali used in the presenting solution is: borax or metaborate, then the activating solution carries an amount of which ranges between five and ten times what the original solution carries. But if the alkali salt is sodium or potassium carbonate, then its percentage in the solution increases by between two to four times its weight in the original solution.

d) For potassium bromide:
It is rare to add potassium bromide to reactivation solutions, as it is mostly known that the amount of bromide increases after the start of manifestation on its own as a result of the interaction between the presenting solution and the silver bromide present in the film gelatin.
As for the highlighting solutions that lead to fine granules, which contain hypo salt or potassium thiocyanate, among its compounds. Thiocyanate, it is usual for the amount of these salts to increase by approximately three times than it was in the original solution.

If many of the show solutions accept the renewal of their activity, however, it may not be possible for some other show solutions due to the speed of their deterioration, as an example of that pyro show solutions which are usually prepared from two solutions, one of which carries a reducing agent and the second carries alkaline substances. It is also not customary to prepare solutions to reactivate show solutions that contain caustic alkali (2).