Quality Of Vision

Double Glazing Units - IGU's

High Standards of product and service are of paramount importance to us at Ashford Glass Supplies.


Insulated Glass Units commonly known as double glazing provide a high standard of vision.


The following is a guide to the quality that our customers can expect and the limitations which are deemed acceptable throughout the Glass & Glazing industry.


Glass used in the manufacture of IGUs is similar to that used traditionally for single glass glazing and will. therefore, have a similar level of visual quality.


Viewing IGUs for scratches on the outer faces of the panes must be carried out before any rendering, plastering or other works adjacent to the glazing takes place,


The Professional check to Standard

  • Stand in the room no less than 2 metres away from the IGU and look directly through the IGU
  • Do so in natural daylight, but not directly towards the sun and with no visible moisture on the surface of the glass
  • Where it is not possible to stand at the correct distance, then stand as far away as possible
  • Exclude a 50mm wide band around the edge of the glass, this is deemed the non visual area
  • The glass must be viewed at a 90 degree angle (straight on) to the window
Expectations & Limitations

Flat transparent glass, including laminated or toughened (tempered) or coated glass is acceptable if the following are neither obtrusive nor bunched:

  • Bubbles or Blisters
  • fine scratches not more than 25mm Long
  • minute particles (desiccant, jointing compound)
The obtrusiveness of any blemishes or marks is judged by looking through the glass, ideally at an external object, not at the blemish directly, and must be viewed in natural light. It must be understood that the glass used in double glazing is a processed glass, as a consequence, blemishes are to be expected.


Insulated glass units with optical defects such as smears, fingerprints or other dirt on the cavity faces(internally), or extraneous material in the cavity are unacceptable, except were small particles of desiccant can be seen.


If you would like any further information, please call us on:


01233 633775