Made in the USA
Made in the USA 
Borosilicate Glass Manufacturer of Lenses, Reflectors, Refractors

Quality Control in Borosilicate Glass Manufacturing

At Jeannette Specialty Glass, quality control means setting rigorous standards for producing the finest commercial, industrial, scientific, and military glass.  We're known for our exceptional specialty glass products, and our dedicated Quality Control Department assures that JSG remains an industry leader when it comes to product quality.

Inspection and Audit System

  • Multiple Inspection QC Process (Manufacturing/Finishing Facility Testing)
  • 100% Piece Inspection
  •  Specification Standards ensured via:
    • Go/No-Go Gauges are used to ensure Customer specifications are met
    • Thermal Shock Testing each shift
    • Annealing Testing
    • Specific Customer Qualifications
  • Audit System (Warehouse QC Testing)
  • Minimum 5% Audit

At Jeannette Specialty Glass, Quality Control Meetings are held monthly to review specific standards of quality.  Our highly trained QC department undergoes annual training and constantly strives to maintain JSG's rigorous quality control requirements.

Quality Control Testing

Thermal Shock Testing

  • Minimum In-house Testing
    • 200°F - Oven
    • 65°F - Water
  •  Customer's Specifications
  • Thermal Shock Test Procedure (Download our PDF file)
    • Specific customer thermal shock specifications are available upon request

Rain Testing

  • Jeannette Specialty Glass' QC department specializes in rain simulation testing

Strain Testing

  • Annealing
    • Annealing QC process is tested multiple times per shift
  •  Polariscope
    •  Polariscope strain testing is used for testing the annealing of the glass
    • Strain testing is performed twice a shift
  •  Impact-Testing
    • Impact Testing is performed in heat-strengthening production
    • Customer's specifications

Return Policy

  • Returns are made after authorization from Jeannette Specialty Glass' Quality Control Department


Contact JSG today for more information on our Quality Control Program.


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