We all know that regular glass has to be handled with care, because, it can break into sharp-edged pieces that can cause severe injuries and lacerations. So, this type of glass is not usually used in applications, that can pose danger, if the glass is broken. In such cases, toughened glass or tempered glass is preferred. This glass is used in numerous applications, like sliding glass doors, windows of passenger vehicles, diving mask, cookware and is also an important component in bulletproof glass. It is said to be four to five times stronger than the regular glass and does not break into sharp-edged shards that can cause injuries.
What is Tempered Glass
This glass is made extra strong through the process of manufacturing that involves extreme heating followed by rapid cooling with forced air drafts. Even though, tempered glass refers to the fully tempered glass, this term is used interchangeably with heat-strengthened glass too. While the heat-strengthened version is only twice as stronger as the regular glass, fully tempered glass is almost four to five times stronger. This glass is much valued for its strength. One of the advantages of tempered glass is that this glass breaks into small oval-shaped pebble-like pieces and thus eliminates the risk of injury. It is found to be more resistant to high temperatures, as compared to regular glass and are less prone to cracks. Unlike the regular glass that breaks into pieces, the entire tempered glass panels shatter at once. It is commonly used in making the windows of ovens, computer screens, tub enclosures, shower doors and skylights. The disadvantage of this glass is that it is cut to the required size and pressed into the desired shape, before toughening. Once tempered, it cannot be re-worked easily.
Cutting Tempered Glass
In order to cut tempered glass, you have to heat it to around 900 degrees and then allow it to cool for around eight to ten hours. This can be done by placing the glass in a craft oven, which is set to 900° F. Heat the glass till it reaches this temperature and then turn off the oven. Allow the glass as well as the oven to get cool for at least eight to ten hours. Once it gets cool, remove it from the oven and keep on a flat surface. Keep the T-square along the cut line. Use a glass cutter, which is dipped in kerosene (this helps in achieving a smoother cut). Now, gently cut the glass with the cutter, along the straight edge. Make sure to apply a moderate pressure and finish the task with one smooth motion, along the entire line. This action should not be repeated for a second time. All you have to do is to insert an ¼ inch dowel just beneath the scratch you have made on the glass and gently apply pressure on either side of the scratch, so that the glass breaks through the scratch. The next step is to lightly rub the whetstone along the cut edges of the glass, so as to give a round finish.
You should never try to cut tempered cut directly. Before cutting tempered glass, you have to heat and cool the glass as mentioned above. Above all, always wear eye protection and gloves while cutting glass, so as to avoid accidental injuries.
