محاليل اظهار الصور الموجبة بالاميدول .. كتاب التحميض والطبع والتكبير

Solutions for displaying cations of amidol:

Brightening solutions «Amidol» are characterized by their ability to increase the blackness of the positive image, but the following are faulty:

(a) What it causes of discoloration of the fingers.

(b) Its inability to remain for a long time without deterioration, which calls for its use immediately after its installation.

For the aforementioned reasons, it can be said that “palmitol” or “hydroquinone” highlighting solutions are indispensable for “amidol solutions.” The former is also capable of increasing the blackness of the image, especially if the amount of potassium bromide is reduced and any of the substances known as “appearance enhancers” previously referred to on pages 85 are added to the solution. 86 . In the following, we present examples of the composition of some amidol show solutions. It is noted that it is free from the usual alkaline salts, content with what sodium sulfite has a low degree of alkalinity. It is also seen in the table on page 336 that the amount of potassium bromide has decreased significantly in the case of showing chloride leaves.

Controlling the degree of contrast of the positive image by installing the display solution:

It is possible to control - to some extent - the degree of contrast of the positive image, the amount and type of salts that make up the solution.

a) Increase contrast:

The solutions for showing positive images that increase the contrast of the image do not differ from the usual solutions for showing negative images with hydroquinone and caustic alkali (Hydroquinone) or (with hydroquinone and carbonates) except in what we notice from the lack of potassium bromide in the positive images solutions. (For examples of these solutions, please refer to what has previously been mentioned regarding solutions for showing negative images
which increases the variance).

b) lack of contrast:

The degree of contrast in the positive image can be reduced if we use solutions that show negative images in which metol is used as a reducing agent, noting that the amount of potassium bromide is reduced.

And if this type of solution is characterized by its ability to stay for a long time without damage in addition to not staining the image, it is flawed in what it requires to be fully accurate in estimating the exposure time during the enlargement, as it is very likely that the quality of the image will be affected simply by increasing the nursing period. By 10%. Below is a description of the composition of two display solutions that reduce the contrast of the positive image.

Controlling the degree of contrast of positive images by using two display solutions that differ in their degree of contrast:

It is also possible to control the contrast of the image by using two display solutions, one of which leads to a very low contrast, and the second leads to a very high contrast. As for how to control the degree of contrast. So you are done. By changing the exposure time needed in each of the two previous solutions. If we want to increase the variance, then the duration of the treatment in the first solution should be greatly reduced, while the period of exposure should be increased in the second solution, and vice versa. Nursing should be increased by approximately 30% if it is desired to follow this method to control the variance. The following is a statement of the composition of the two solutions.