ترکیب محاليل الاظهار التى تؤدي الى حبيبات دقيقة .. كتاب التحميض والطبع والتكبير

Composition of highlighting solutions that lead to fine particles:

This type of solutions is divided into three factions:

(a) Typical showing solutions but yielding fine particles.
Normal fine grain developer

(b) Showing solutions with low voltage lead to fine particles.
Low energy fine grain developer

(H) Silver solvent show solutions lead to very fine granules.
Silver solvent fine grain developer

First: The usual highlighting solutions that lead to fine granules:

These solutions are characterized by a low degree of alkalinity, and this is usually done by one of the following two means:

(a) Either a highly alkaline salt (such as sodium carbonate) is used in a solution of low concentration.

(b) or a weakly alkaline salt (such as borax) in a solution more concentrated than the above.

Here we may ask which of the two methods is better? In response, it says that the show solution that carries weakly alkaline salts in a high degree of concentration is characterized by a longer staying power, but if the degree of alkalinity is increased in the show solution, it does not lead to fine particles, but then it enters the family of the usual show solutions, even if we use a factor The reduction is included in the family of reducing agents that usually result in fine grains, such as Meritol or Para-Phenylene-diamine
And under this group are those solutions that usually consist of (mitol - hydroquinone - borax), such as:

ORWO 44 Appearance Solution.
Kodak D.K. Appearance Solution No. 76 76.
Gevaert D. 206 Appearance Solution.

Differences between highlighting solutions that lead to fine granules:
Solutions of this species differ from each other in the following respects:

A) With regard to the degree of concentration of reducing agents: in some of them the percentage of the reducing agent decreases (such as Gephardt Appearance No. 206), and in others it may not contain hydroquinone at all, but rather the amount of methol is increased. In it, hydroquinone is replaced by a reducing agent such as glycin (as is the case in the 10-Edwal-appearing solution).

b) With regard to the degree of alkalinity: with increasing the degree of alkalinity, the period of exposure decreases, but if it increases to a large extent, the solution leaves the group of solutions leading to fine particles and moves to the group of usual solutions.
Under this group, solutions are also included that contain nothing but methol and sodium sulfate, which then performs a double action as a preservative and an alkali at the same time. An example of this is Ferranian R. 33 (Kodak) solution. Another salt may be added to the above, which is sodium bisulfate (Kodak 25 D appearance). These last two solutions only have a superficial effect on the films, so their effect on the upper surface of the gelatin layer greatly exceeds their effect on the lower layers of it, because they do not penetrate into the layers. The lower layers penetrate with the same force with which other solutions penetrate, and this results in the reduction of silver salts in the upper layer only. If the period of exposure exceeds the prescribed limit, the appearance penetrates into the lower layers of the film and the silver salts are reduced in these layers as well, then the reduced metallic silver granules begin. In contacting each other and forming a larger granule, and so on (as we have seen in Figures 34 and 35), then this type of solution has lost its advantage. Therefore, in order to obtain really fine granules, it is required that the period of blanching be appropriate, as excessive blotching may also be a cause for an increase in the size of the granules despite the use of a blotting solution of this type.