What is Tempered Glass for Shower Doors? - Safety Glass Explained
Tempered Glass
All shower glass must be tempered, or turned into "safety glass" to comply with local building codes. This requires heating the glass upwards of 1,200° - 1,500° and cooling rapidly in a quench. Some of glass panels require fabrication for hinges, clamps and handles (i.e. holes and cutouts drilled in the glass), so it can be mounted safely. If a hole is too close to the edge, < 1.5x thickness of glass between edge of hole and edge of glass, it will break in oven and can cause major damage. In order to solve this, relief cut is done. This cut is there to prevent glass from breaking during tempering. This is basically a 1/16" saw-cut, allowing the small portion of glass to move freely under such extreme conditions during tempering. This is common in glass tempering, and it not damage by any means.