العوامل التي تؤثر في الوقت اللازم لعملية الاظهار .. كتاب أسس التصوير الضوئي

Factors affecting the time required for the display process:

First: the temperature:

The process of displaying is subject to the chemical reaction laws that decide that with a high temperature, chemical reactions are activated, so we are forced to decrease the time required for displaying, and with a decrease in temperature, the time required for displaying increases. 20 m) The following is a statement of the effect of different temperatures on the sensitive layers.

​1) Less than 10 °C, the hydroquinone effect is not shown.

2) From 10 pm to 15 pm the display process is inactive.

3) From 18 °C - 20 °C, the exposure process is in an appropriate activity that does not result in damage to the sensitive layer. It is the most appropriate temperature to obtain the best results.

4) The degree of 25°C is the highest degree at which the film can be shown safely without fear of the gelatin.

5) From 25°C - 28°C, the film begins to swell or swell and become touchable, otherwise it is removed from the abutment.

6) At a temperature of 28 °C or above, the gelatin layer that forms the sensitive layer dissolves and the film becomes worthless.

Second - moving the sensitive layer:

The blanching process is activated if the sensitive layer is stirred more in the blotting solution, as is the case with any chemical process that is activated by increasing stirring. The blanching process takes place in one of the following forms:

(1) On a dish plate, move the film by hand.

(2) In a tank, it may accommodate only one film in which the film is stirred regularly, or in a tank that can accommodate more than one film in which the films are stirred several times in the principle of the process often to remove possible air bubbles - and this type is often used in Shops and shops require an increase in time by 25 to 30% over the time needed to appear on a plate, and the wisdom in that is that by moving the film in a continuous movement, the following results:

a) The temperature rises and the display becomes active. as a result .

B) A non-fatigued appearance of acid adhesion is renewed for the sensitive layer. Among the types of tanks are what are prepared so that the film can be installed in it in daylight without the need for a dark room.

Third :

The type of film and its speed of sensitivity: a certain film may need four minutes to show it, and another film needs five minutes to show it in the same circumstances in which the first film was shown.

Fourth: The required degree of contrast:

The degree of contrast depends on the duration of showing the film, and we will come back to explain this preferably in the section of studying the characteristics of the sensitive layer with graphics.

Fifth: Degree of Concentration:

When using a diluted solution, we need a longer time to show than if it was concentrated, and we will come back to explaining this factor in detail.

Sixth: the difference in the composition of the highlighting solution:

By increasing the proportions of some of the salts that make up the presenting solution, the required time is prolonged or decreased according to the properties of each salt. Research laboratories in the factories that produce photographic supplies have decided the time required for the displaying process for each type of displaying solutions that they decide. In the following tables are practical examples of the installation of some types of highlighting solutions and the appropriate time.

Display time:

A- Four minutes at a temperature of 20 degrees Celsius if the display is on a plate.

B - Five minutes at a temperature of 20 degrees Celsius if the display is in the tank.


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