Tempered glass is much harder than regular glass. However, if you cut, drill, or otherwise modify it after tempering, then it is highly likely that it will shatter into small pieces because it is more brittle than regular glass. Even if it doesn’t break, the glass will be compromised and will not be as strong as intended.
It’s important to do this after cutting the glass, in case any cracks or other damages were caused while cutting the glass.
You can sand the edges by hand, with an electric sander, or with a rotary tool like a Dremel tool.
You can just use regular, cool water. There is no need for any special cleaners.
You can use any type of oven or kiln to temper glass, as long as the temperatures can get high enough, although a tempering oven is ideal.
In a glass tempering facility, you will be able to be more precise with the times because of the special ovens they have. However, if you are tempering glass in less-scientific conditions, then you will have to experiment to learn exactly how long it takes to temper different thicknesses of glass in your oven or kiln.
In facilities specially designed for tempering glass, there will be a special quenching oven that the glass gets transferred to after the oven.
If you are tempering glass in a special facility with a quenching oven, the oven will have nozzles to blast cool air preset at different angles. If you are working with more limited resources, you can use a compressed air hose and move it constantly while blasting the glass to hit all the different angles. Tempered glass is about 6 times stronger than regular glass. When it does break, it will break into small shards that are much safer than the jagged pieces that regular glass (called floating glass) breaks into.
These quench marks can look like dark, shady spots or lines that stretch across the surface of the glass.
