تجفيف الورق الحساس .. كتاب التحميض والطبع والتكبير

Drying sensitive paper:

The degree of glossiness of sensitive paper is determined by determining the appropriate method for drying it. If it is matte or semi-matt, then the water spots on it should be removed first with a piece of dry cotton, chamois, or a clean soft sponge, or the image should be wrapped between two sheets of absorbent paper. (Fig. 191) Then it is left to dry on a stretched cloth in a wood frame (Fig. 91-b), or attached to special clamps (Fig. 91--) to dry in the air, but it often curves in this case, and then it can be re-straightened according to one of the following methods: The two methods shown in (Fig. 93).

Although slow drying at normal temperatures is sufficient to perform the required purpose, there are cases that call for assistance in speedy drying of the image (such as if the work is in a damp, cold place), and then electric dryers are used, and electric lamps that emit infrared rays are sometimes used (i.e. they emit Thermal energy) to raise the temperature in a special cupboard for drying, or to raise the temperature in the room in general.

If the factory has an electric dryer for paper (Fig. 93, 92, 94), then it is easier to dry matte or half-matte sensitive paper with this dryer, taking into account directing its surface towards the cloth, and it is wrong to direct it towards the metal polishing pad..

And it is possible to increase the speed of drying by first dipping the image in alcohol so that it partially replaces the water. This idea relies on the ability of alcohol to quickly evaporate, more than the speed of evaporation of water. As for the originally glossy papers, they require drying them while working to increase their polishing. Before starting to polish the images, it must be verified that the gelatin layer has completely hardened.

Although sensitive paper with a glossy surface may not require additional polishing, the degree of its glossiness can be greatly increased if it is pressed completely on a clean, highly polished hard surface, and pressure is usually used with a rubber roller (Fig. 92 - -) rotating on a pomegranate. Yes » and it expels all the water droplets that are attached to the surface of the image.

The polishing process may be done cold, by pressing the wet image onto a sheet of glass and then leaving it to dry and fall off on its own, or it may be done in a hot way, by pressing the wet image onto a highly polished metal polishing plate usually known as a Ferrotype Plate and then placed in a delicate paper dryer ( Figure 92-92-d) The image is left to dry and separate from the polishing pad on its own.

Whether glass is used or metal polishing pads are used, they must generally be clean and completely free of scratches. The cleaning process may be done with cotton dipped in alcohol, then by scrubbing with talcum powder, and then removing it well until all traces of it disappear. The board may be cleaned with so-called glazing solutions, which are specially manufactured by photographic material factories for this purpose. It is more appropriate, if the last solution is found, to dip the images in its diluted solution for a short period (its duration is usually indicated on the solution bottle). Sometimes special machines are used to dry and polish the images if the daily production is greatly increased by a piece (Fig. 94).

It is very likely that the pictures will stick to the glass or polishing pads if they are not cleaned well, or if the polishing solution is exhausted. Also, it is certain that scratches will appear on the surface of the image if the glass or polishing pads are scratched, and the image may also have cracks or curved marks if the heat is not uniformly distributed over the entire area of ​​the image.