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The table shows how the two systems rate high-brightness papers, but there is no simple way to convert between the two systems because the test methods are so different. [4] The ISO rating is higher and can be over 100. This is because contemporary white paper incorporates fluorescent whitening agents (FWA). Because the ISO standard only ...
Polysulfide or 'direct' toners – these do not require a bleaching stage. Except for polysulfide toners, sepia toning is done in three stages. The print is first soaked in a potassium ferricyanide bleach to reconvert the metallic silver to silver halide. The print is washed to remove excess potassium ferricyanide and then immersed into a bath ...
Use of recovered paper increased in the 1970s mainly in graphic and hygienic papers, and accelerated in the 1980s. The annual growth in use of recovered paper increased by 6% between 1980 and 1996. The use of virgin fibres only increased 2% in the same period. In 1997 recovered paper production was 42% of the total paper production. [2]
Photographic printing is the process of producing a final image on paper for viewing, using chemically sensitized paper.The paper is exposed to a photographic negative, a positive transparency (or slide), or a digital image file projected using an enlarger or digital exposure unit such as a LightJet or Minilab printer.
The first is the exposure area, where the sandwich of the two sheets (the master and the diazo paper) passes in front of an ultraviolet lamp. Ultraviolet light penetrates the original and neutralizes the light-sensitive diazonium salt wherever there is no image on the master. These areas become the white areas on the copy.
Bleach bypass, also known as skip bleach or silver retention, is a chemical effect which entails either the partial or complete skipping of the bleaching function during the processing of a color film. By doing this, the silver is retained in the emulsion along with the color dyes. The result is a black-and-white image over a color image.
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Negative or positive images can be obtained by blocking UV light from reaching the sensitized material. For example, a negative image can be produced by placing a leaf upon paper treated with this solution and exposing to sunlight for 10 to 20 minutes. The paper will retain the image of the leaf after it has been rinsed with water.