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Friday
March 22, 2019



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History - Industry - PPG Tarentum



Revolving Iron Disks Grinding Surface of Plate Glass





Here we see a plate of glass after it has been thoroughly set and is nearly ready for sale. The machines now used for the grinding save a great deal of time. The improvement is chiefly in the March transfer polishing table, which combines the advantages of reducing the temperature of the glass while grinding, by circulating water below it, thus permitting a much higher speed in the grinders, with a device for polishing the under side of the plate, without the frequently disastrous operation of removing it from its plaster bed and turning it over. This transfer table is also movable from grinder to polisher, effecting in this way a considerable saving of time, while ensuring the greatest security in handling.

There used to be many restrictions upon the output of the glass-workers by the Glass-Workers' Union but immigrants, willing to work on an unlimited plan, forced themselves into the trade, and this compelled the Union, for self-protection, to remove the restrictions on its members. The increased production because of the removal of the union limitations amounted, in one case, to 100 per cent, and the increase of earnings to about fifteen per cent. A discriminating entrance fee, so effective in other instances, is employed by the flint-glass workers to protect themselves against an influx of cheap foreign workmen.


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