top of page

Glass Quality Guidelines

All our glass products are made to the highest standard.  Due to the processes that glass has to go through and its properties, appearance can be vary. The following guidelines set out the tolerances you can expect, this has been created with information from our manufacturers and also the Glass and Glazing Federation (GGF)


When viewing glass:

  • The glass should be in a vertical plane and at a right angle from the room side

  • No nearer than 2 meters - 3 meters is perect

  • Use natural daylight - not direct sunlight 

  • The glass should be dry

  • Look through the glass not at it

  • Any defects should be identified within 2 seconds 

Glass quality
Glass quality

Spot Faults 

Bubbles, stones and seeds 

Glass quality

Glass quality
Punctual defect 

Spots and pinholes in the

glass coating

Glass quality
Linear/extended faults

Uniformity defects and stains i.e. scuff marks, heavy scratches, lines deposits impressions, etc are allowed as long as they are not visually disturbing.

Colour matching

Glazing technology is continually evolving; therefore new units installed alongside existing units may not exactly match. This is not a fault.

Condensation External:

Condensation forming on the outdoor face is a positive indicator of the thermal efficiency of the IGU. This is not a IGU fault.

Condensation Internal:

Condensation forming on the glass surface facing the room is due to warm, moist air trapped in the building. This indicates a problem with building itself suggesting that increased air ventilation is required – the condensation on the glass is a symptom not a fault.

bottom of page