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Extrusion of hollow arc carbon from a hydraulic press.
Arc carbons cut into lengths for further processing.
Hand placement of arc carbons into saggers for oven baking.
One of many visual inspections during arc carbon manufacture.
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HISTORY from page 8
of any known artificial light source, and provides a color quality matching that of sunlight.
The brightness of the high-intensity arc results from a combination of high current density (resulting from a high concentration of electrons in the arc stream I and an atmosphere on the positive crater region that is rich in flame materials volatilized from the core in the positive carbon. As the carbon burns to form a crater, the core is exposed to the extreme arc temperatures in excess of 10.000 degrees F., approximately that of the sun's surface.
The Story of Fostorsa Know-How
As is true of any quality product, the manufacture of arc carbons begins with careful selection and preparation of raw materials.
In the extrusion operation, carbon is squeezed out by the pressure of an hydraulic ram.
At the other end of the 70-foot run, lengths of carbon are cut and checked for size. This is but one of approximately 60 quality control inspections the arc carbons will undergo during their manufacture.
Loaded saggers are next placed in huge gas-fired baking ovens, and the lengthy baking cycle begins. A temperature in excess of 1800 degrees F. is reached, which fully "bakes" the carbons.
The longer lengths of carbon are then cut to more nearly their finished size, and several more inspections are made, including a visual check. Also very important is the straightness of the arc carbon, and every one is passed under an accurately-positioned guage, with those that are only a few thousandths of an inch out of alignment rejected.
The carbons are then baked again briefly to set the core material, and the positive carbons undergo X-ray examination that detects any core flaws.
As part of its continuing technical service to motion picture exhibitors. National Carbon also evaluates other light sources that are introduced from time to time and reports its findings. The carbon arc, however, continues to outperform all other sources of screen illumination, and still holds the greatest promise as the most brilliant li«ht source of the future.
The Parma Research Story
To project motion pictures, or to illuminate motion picture studios, it is necessary to collect the light emitted by the carbon arc and project it where needed. Research devoted to improving the process requires study
■■■HI
A close check of arc carbon diameter prior to further processing.
All arc carbons must pass stringent straightness tests.
Projection booth is operated to test carbons under actual theatre conditions.
Recording spectroradiometer matically measures and charts spectrum.
International Projectionist August,
autocolor
1963