Toners, photographers

Industrial Amlications Dye laser photoresists liquid crystals semiconductor integrated circuits thin films recording materials inks toners photographic materials ... 

Selenium is used in Xerography for reproducing and copying documents, letters, etc. It is used by the glass industry to decolorize glass and to make ruby-colored glasses and enamels. It is also used as a photographic toner, and as an additive to stainless steel. 

Fig. 11. Magnified photograph of a single carrier bead, 100 micrometers in diameter, showing smaller, attached toner particles.

Aronnd 10% of all new substances registered are nsed for the purposes of plastics processing. A further approximately 10% of new substance registrations are in each case for (i) dyes (especially for the textile industry) and (ii) photochemicals (photographic industiy and toners in the paper industry) and also (iii) cosmetics and perfumes. The majority of relevant substance innovations appear to take place in this relatively narrow market sector, while here too a relevant proportion of process iimovations could be in processing (with the exception of cosmetics and perfumes). 

The easiest method to achieve warm tones is to choose a paper that is susceptible through direct development. These include Ilford Multigrade FB Warmtone, Kentmere Kentona, and Fotokemika Emaks. Though there used to be many more papers of this variety manufacturers have moved away from making them in favor of neutral-tone papers.2 While this is a loss to fine-art photographers, warm tones can still be achieved—and in great variety—through the use of toners. 

The classic formula for gold protective toning is Kodak GP-1 Gold Protective Solution. Like selenium toner, GP-1 not only protects the print but causes a minimum color shift. What shift there may be is toward a slight blue-black that some photographers find pleasing. With some papers, GP-1 will also improve separation in the highlights. 

Another source of chemicals to which we can be exposed, apart from food, is our workplace. This could be a factory where solvents or metals are used or chemicals synthesized, a printing press, a photographic film developer or a scientific laboratory. Even workers in offices can be exposed to photocopier toners, for example. Then there are the chemicals we knowingly imbibe, such as drugs, stimulants like coffee, and of course alcoholic drinks. 

Major polymer applications sizing agents, binders, protective colloids, photographic papers, toners, fihn, water-soluble laundry bags, seed tapes, sanitary pads, belts, printing rolls, controlled drug delivery, membranes... 

The photographic industry too makes ample use of many of these substances as stabilizers, anti-fogging agents, toners, anti-bronzing or anti-plumming agents and the like. 

Figure 9. Magnetic brush (top) and magnetic brush bristle consisting of chain of large carrier beads covered with toner powder (bottom). Key A, pickup magnet and B, magnet. (Reproduced, with permission, from Ref. 50. Copyright 1974, Society of Photographic Scientists and Engineers.)...

A theoretical model to relate the Wiener spectrum to the toner deposit parameters is difficult to construct because the mathematical difficulties of dealing with projections of transforms of probability distributions quickly "hide" any simple relationships. Models have been constructed however for a crowded monolayer photographic emulsion (11), and for multilayers of emulsion (12). Although the analysis was done for one-dimensional geometry, extension to two dimensions was outlined. A different approach will be used here, which relies on the linearity property of the Fourier transform, and assumes that the location of the toner particles is independent of neighbors. 

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