How to Tell If Glass Is Tempered

Tempered glass, which is also known as "safety glass" is often used in high-risk areas where shattered glass could present a major safety hazard. If you have a piece of glass you're not sure about, it may be difficult to tell the difference between tempered glass and regular glass, even when looking at it up-close. There are methods you can use to determine whether the glass in question is tempered or not.

Things You'll Need

• Polarized sunglasses

Instructions

1. Check the corners of the piece of glass. If the glass is tempered, it is required for the manufacturer to etch the four corners, identifying it as tempered or safety glass.

2. Look for dimpling and imperfections, which were caused during the heating process. Tongs used to remove tempered glass from heat often leave small impressions in the glass that can identified if you look closely.

3. View glass at an angle through polarized sunglasses. Polarized sunglasses expose black lines in the glass that occurred during the heating process. These lines become more prominent at sharper angles.

4. Hold the glass out straight and look for signs of warping or bending. Sometimes the heating process causes mild warping that is easy to identify.

5. Analyze the shattered remains. Safety glass is designed to shatter completely, leaving behind no large shards on which a person might harm themselves.

References

• Tempered Glass
• How to Clean Tempered Glass
• Safety Glass for Inspectors