الافلام والزجاج الحساس المعد للحصول على صور موجبة شفافة .كتاب التحميض والطبع والتكبير

Sensitive films and glass prepared to obtain transparent positive images:

The properties of photosensitive films or glass prepared to obtain transparent positive images are similar to the properties of sensitive papers intended for printing or enlarging (whether in terms of optical properties or degree of contrast), but they differ mainly in the type of support.

There are three classes of raw materials intended for transparent positive images, which we describe as follows:

1- Magic Lantern Slide Plates:

It is a support of glass covered with a positive sensitive layer.
It is usually manufactured according to specific internationally agreed standards.

The glass may be from the family of kaurides, bromide, or chlorobromide, and it is used according to the same principles previously explained regarding the use of sensitive papers, where one of the mother flags is positive. - Hydroquinone) for approximately one minute at a temperature of 18°C. It is better to show this sensitive glass in a relatively dark yellow safety light.

Bromide glass is much faster in its sensitivity than chloride glass, and magnification is good for images, and it leads to black colors when treated in a solution of a disappearing appearance, like those types previously mentioned regarding sensitive papers that lead to warm colors.

It may be difficult for some to divide positive sensitive glass into separate small parts to use as experiments to estimate the correct exposure time (as we have previously known about positive sensitive paper, p. Estimating the correct nursing period. Therefore, it is more correct to look for sensitive paper that matches the speed of its sensitivity and the degree of contrast with the speed of sensitivity and the degree of contrast of the glass that we are asking to use so that this paper can be used in doing preliminary experiments before enlarging the final image on the sensitive glass. The factories that produce this type of glass refer to one of the types of sensitive papers they produce as a type that is equal in its characteristics to the sensitive glass it produces. The novice photographer may be deceived in the processes of enlarging and printing images on sensitive glass when he follows the steps of the appearance of the image while it is in the display solution, as the degree of its density and the degree of contrast when looking at it while it is in the basin differ from the real degrees of contrast and density that can only be estimated by looking at the permeating rays.

B - Transparency films

These films are of different sizes, they may be 6 x 9 cm or less, or more than 3 x 40 cm or more. Its characteristics do not differ from what was previously mentioned regarding positive or sensitive glass
Positive sensitive leaves.

C - Positive films of the same type and dimensions as 35 mm cinematic films with perforated sides: Positive Ciné film:

They are similar to slow corundum papers either in speed of sensitivity or in their spectral sensitivity, both of which are insensitive to colors, except that the films have a celluloid backing.