Quality Borosilicate Flat Glass Circles In Stock

Annealed Borosilicate - Clear 
Good for normal service where one surface is heated to a maximum temperature of 446°F (230°C), using 1/4" or thicker glass. The temperature difference between ambient and process should not exceed 150°F.
Tempered Borosilicate - Clear
Recommended for use where higher pressures are required than can be obtained with Annealed Borosilicate. Maximum service temperature is 500°F (260°C). No corrosion to surface, nor severe chill can be tolerated. 
Cobalt Blue Borosilicate Furnace - Blue
Used to reduce glare when observing flame, smoke, and ash intensity in power plants and marine boilers. Thickness up to 1/4". 

Fused Quartz - Clear
For industrial and laboratory applications. Can be used continuously at 1742°F (950°C). Commercial Grade is standard. Optical Grade is available. 


Best used in:

  • Furnaces, Ovens 
  • Observation Equipment 
  • Flow Indicators
  • Pressure Vessels/TanksTempering

Tempering greatly increases the strength of glass and helps it overcome the damaging effect of scratches and other surface defects. Glass is heated to a specified point above its annealing temperature, then quickly quenched causing the surface to shrink and harden. While the interior cools more slowly it tries to shrink, putting itself in tension and creating a compressive stress on the surface. When completed, the surface compression must be overcome and a tensile stress introduced before the glass can be harmed. Thus, the mechanical and impact strength as well as the thermal shock resistance are improved greatly.


Expedite Quick Ship Times Available upon Request with Standard Shipping 5-7 days.  $25.00 Minimum Order


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