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Film Processing Equipment
Sheet Film Hangers

Photography (Basic) - Introduction to photography and other graphic techniques
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standpipe to hold water in the sink at the correct depth, yet still allow water to flow out (fig. 10-1). SAFELIGHTS The  function  of  a  safelight  is  to  transmit  the maximum amount of light that can be used safely without  damaging  the  sensitized  materials  being processed. The color sensitivity of different sensitized materials varies. Therefore, the color and intensity of transmitted  light  must  be  varied  accordingly.  A darkroom safelight is the combination of a rated light source and a filter designated to protect a specific sensitized  material. The word safe. of course, is a relative term since no sensitized photographic materials are ever completely safe from the effects of safelight illumination. However, a filtered light is accepted as safe when the sensitized materials can be handled under the illumination with no evidence of fogging for at least twice as long as the normal  processing  time.  No  procedures  must  be followed  precisely  when  safelights  are  used: 303.23 Figure 10-1.–Photographic processing sink Use only the size of incandescent bulb specified; for example, 7 1/2 watt, 15 watt, or 25 watt. Handle  sensitized  material  at  the  distance recommended  by  the  manufacturer.  This  is  usually between 3 and 6 feet. To determine whether a safelight is safe, you should follow  these  procedures: 1. In the dark, place a sheet of unexposed film, emulsion-side  up, on the working area where the film is to be processed. 2.   Place several coins on the emulsion and turn on the safelight. Leave the safelight on for twice the length of  time  the  film  will  normally  be  processed. 3. Process the film normally and check to see whether there is less density in the areas covered by the coins. When there is less density, it indicates the film was fogged by the safelight and the safelight is not safe. A safelight that causes fogging may be corrected by replacing the filter, by installing a lower rated bulb, or 10-10







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