Glass Inspection Standards

All LoE coated glass used by Value Windows and Doors conforms to the following ASTM Standards

Documents Referenced

  • ASTM C 1036-06 (Standard Specification for Flat Glass) Q3/Glazing Select
  • ASTM C 1048-04 (Standard Specification for Heat-Treated Flat Glass)
  • ASTM C 1376-03 (Standard Specification for Pyrolytic and Vacuum Deposition Coatings on Flat Glass) Kind CV specification.

Surface Imperfections

All inspections are done with the viewing angle at 90 degrees to the glass surface, uniform diffused lighting that stimulates daylight, and with the inspector looking through rather than at the glass surface. Architectural glass that is produced as annealed, tempered, non Low-E insulated, or laminated.

Bubbles, Pits, Knots, and Dirt

With the inspector standing 39″ from the glass surface, and glass thickness is ¼” or less, bubbles, pits, knots, or dirt are allowed if the average of blemish’s length and width is 1/16″ or less.
Blemishes with an average length and width of 3/32″ are allowed if they are separated from a similar blemish by at least 24″.
Bubbles, pits, knots, and dirt are not allowed if their average length and width exceeds 3/32″.

Edge Chips

  • DEPTH: A chip is allowed if its depth does not exceed 50% of the glass thickness.
  • WIDTH: A chip is allowed up to half of the glass thickness or ¼”, whichever is greater. For mirrors, the limit is half of the mirror thickness or 1/16″, whichever is greater.
  • LENGTH: A chip is allowed if its length does not exceed two times its width.

Architectural glass coated using a hard or soft coat low-E process may have surface distortions due to the heat treating process.
The visibility of this distortion depends on factors such as:

  • The size and shape of the glass
  • The location of the glass in the building
  • The distance from which the glass is viewed

Reflective coated glass and the expansion/contraction of air space within insulated units can also enhance this distortion. These are not considered defects and are not cause for rejection.

Maximum Bow and Warp Tolerances

Scratches and Rubs

  • The inspector starts at a 120″ distance from the glass surface.
  • The inspector moves closer until the scratch or rub is first detected.
  • If the scratch or rub is visible at 120″, is over 3″ long, and is located in the central viewing area (defined as 80% of the length and 80% of the width dimensions centered on the lite of glass), it is cause for rejection.

Coating Pinholes

  • Pinholes greater than 1/16″ are not allowed.
  • Pinholes less than 1/16″ are allowed if they are outside the central viewing area.
  • Three or more pinholes greater than 3/64″ within a 6″ diameter cluster are not allowed at a 120″ distance.

Coloration

Low-E coated glass may exhibit a hue or coloration that is not apparent in architectural samples, especially in shaded or darkened light or when viewed at a glancing angle.
This coloration is inherent to the coating process and is not a reason for rejection.

The previous information is copyrighted and is available at http://www.astm.org/