PURPOSE: To provide a glass ruler free of the possibility of gradations being lost or broken, having high accuracy and excellent strength and hardness and being reliable and safe to use, by printing gradations or the like on a polished predetermined glass plate in an inorganic ink containing metal ions, drying the ink, followed by baking at a specified temperature to cause coloring through permeation of the metal ions, and quenching the glass plate down to a specified temperature.
CONSTITUTION: A plate glass 1 is cut to a predetermined width and a predetermined length. The cut piece of the plate glass is provided with a slant surface 3 by chamfering at least one side edge of a untinned surface 2 on one side thereof, and end faces 4, 5 and the slant surface are polished. Edge parts between adjacent faces are rounded by polishing, and reference lines and graduations 7 are screen-printed on a tinned surface 6 on the other side thereof at the side edge provided with the slant surface, by using an inorganic ink containing metal ions. The plate glass is then baked in a baking furnace at a plate glass surface temperature of 600W650°C to cause the metal ions in the ink to permeate into the glass through an ion exchange reaction with alkali ions in the glass, with the result of coloring. Then, the plate glass is quench to a temperature of about 400°C to convert the glass into a tempered glass, followed by finishing through cleaning. The reference lines and graduations will not be lost or broken, because they are colored through permeation, so that the glass ruler obtained can be used safely. In addition, because of marked enhancement of transparency, strength and hardness, the glass ruler is easy to handle.
IKEDA GLASS KK
COTEC CO LTD
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