Glass Inspection & Defects

“It’s much more difficult to explain expectations around industry standards once the Owner has already seen the glass… and decided it is not acceptable to their personal expectations.” 

Glass isn’t perfect. It’s a fact worth repeating because few things cause more heartburn than glass industry standards, especially when those standards don’t align with the client’s expectations. Visible glass defects are the kicker in the luxury custom home niche. Expectations are high for everything, and glass isn’t perfect. In fact, the larger the piece of glass, the less perfect it is allowed to be.

Visible imperfections and defects in glass are covered by glass industry standards that are set by the ASTM (American Society for Testing & Materials). To be honest, ASTM standards span a wide variety of glass issues and it’s not easy to get to the heart of what constitutes a visible defect.

So: When is a defect not a defect?

Quick answer:

  1. Move away from the glass.
  2. Stand back 10 feet.
  3. Face the glass straight-on at 90 degrees.
  4. View in daylight but not direct sunlight
  5. Inspect the glass.

Under these conditions, if you can’t see it from 10 feet – it isn’t a defect.

That’s the short version of the answer.

ASTM’s Official Standards

The official ASTM version of the answer is longer, much longer. The answer to, “what is a defect?” also depends on what defect you are trying to identify. Is your defect in:

  • Flat glass & glazing – ASTM C 1036
  • Heat-treated (tempered glass) – ASTM C 1048
  • Coated glass (used in IG Units) – ASTM C 1376

Each of the standards listed above outline different inspection criteria. Understanding these criteria is very important before pointing out defects and imperfections. The criteria specify things such as inspection distance, lighting requirements, viewing angle, size and dimension of the specimen, etc.

A piece of glass may also be subject to many ASTM standards depending on the fabrication process. For example, a Low-E coated tempered insulated glass unit may require the application of all three standards to evaluate defects!

WSD Quality Standards

Wisconsin Shower Door strives to provide you, our dealers, with high quality fabricated goods. Our goal is to deliver products adhering to the Q2 tolerances outlined in ASTM C 1036.

Our fabrication and delivery process is designed to meet these strict quality requirements. These are some of the procedures in place to minimize defects:

  • limit the handling of glass wherever possible
  • multiple inspection stations throughout the fabrication process to ensure quality
  • use of glass separation and corner protection during loading and shipping

We have written abridged versions of the ASTM standards we adhere to and are provided for your reference.

Managing Expectation

Managing expectations is crucial in any relationship. It’s no different when it comes to managing the expectations of defects and imperfections in glass. As we work together as a supplier and dealer; we hope you can use this information between you and the final customer.

Anyone can find imperfections in glass if they look close enough and hard enough. Glass isn’t perfect. Glass is meant to be looked through, not at.