Accurate dimensions are essential to ensure proper fit-up with frames, gaskets, fixings, and façade systems, especially in unitised curtain walls and high-performance glazing assemblies. Consistent dimensional compliance also helps minimise site rejections, rework, and installation delays.

TGC’s role focuses on independent verification of dimensional compliance against approved drawings, applicable standards, and project-specific tolerances. Inspections are carried out as part of defined quality control checkpoints, with documented reporting to provide assurance to clients, consultants, and contractors that supplied glass meets specified dimensional requirements.

Visual inspection is conducted under controlled lighting and viewing conditions, using defined inspection distances and acceptance criteria. This ensures a consistent, objective assessment aligned with relevant standards and project specifications.

As an independent inspection body, TGC assesses visual quality in accordance with agreed criteria and documents observed non-conformities to support transparent acceptance decisions. This is particularly critical for architectural and façade glass, where visual defects may become more apparent after installation due to reflections, lighting conditions, and viewing angles.

Nickel Sulphide (NiS) Inclusions

Nickel Sulphide inclusions are microscopic impurities that can form during the glass melting process and are generally undetectable through standard visual inspection. Over time, phase transformation within the inclusion can lead to internal stress build-up, potentially causing spontaneous breakage of tempered glass without external impact.

Heat Soak Testing (HST)

To significantly reduce the risk of spontaneous breakage associated with NiS inclusions, Heat Soak Testing is widely specified for critical glazing applications.

During heat soak testing:

• Tempered glass is exposed to elevated temperatures under controlled conditions
• Glass containing critical NiS inclusions is more likely to fail during the test
• Panels that pass the test have a substantially reduced risk of spontaneous failure in service

TGC’s involvement includes independent verification of heat soak testing compliance, review of testing procedures and records, and confirmation that project or specification requirements have been met. While heat soak testing does not completely eliminate NiS-related risk, it is an internationally recognised mitigation measure for high-risk applications such as façades, overhead glazing, and public spaces.

Optical distortions may arise from uneven thickness, improper heat treatment, residual stresses, surface irregularities, or processing effects. These issues can become particularly noticeable in large-format panels or under reflective façade conditions.

TGC conducts optical quality assessments as part of an independent inspection scope, verifying compliance with applicable standards and project-specific visual criteria. Findings are documented to support informed acceptance decisions and to help ensure that installed glass performs as intended, preserving transparency, visual comfort, and architectural intent.