The Toned Toned and Selenium
The turning (born in between 1800 and 1900) is a way as to change a release by acting directly on the component of silver present in the emulsion of the paper through the use of chemical agents in order to alter the colors of the images in black and white.
There are three main types of viraggio.Il first type it transforms silver crystals making them completely immune to light and weathering. In this category fall the color changes to gold, selenium and sepia. A second type of color change consists in covering the silver crystals, as is the case with blue toning. The third type produces the oxidation of the silver crystals akusewa. By oxidizing the entire surface of the print it will go to avoid that, over time, some areas are likely to deteriorate more or less than others, then standardizing the aging of the picture. In this category fall the color changes of the purple type.
Sepia toning is the most common among the types listed above (and which is dedicated to a different article), but a second color change, the selenium, provides results very interesting and we will describe below.
The benefits of selenium toner are specifically linked to the preservation of the image from the first moment when we extract the paper from the bathrooms. The chemical compound (attention, is toxic) transforms the silver in the photo paper (this type of toning makes maximum when using two kinds of photo paper: paper silver bromide and paper to chlorobromide, both fiber base papers ) selenide silver, a silver component much more resistant to weather and a long list of contaminants that, in time or in the darkroom, may come into contact with the photo paper.
It also allows to obtain blacks and grays more loads without changing the white (this effect is proportional to the amount of silver present in the emulsion of the photographic paper) as well as provides (thanks to the presence of bromide) to the colors present in the image to a cooler color than than it would in a photo does not turn.
Before the color change. The color change is to act in the press, its colors, the emulsion of the photographic paper. In short, the chemical goes to attack in some way the emulsion (we will see later how it works), which means that the press must be perfectly fixed and washed. A washing approximate make printing too vulnerable to chemicals its toning, ruining it.
The development time. Decrease it by 10%. The color change, as mentioned, intensifies blacks, creating the potential for loss of detail in shadows.