Can You Drill Holes In Tempered Glass?

Thermally engineered tempered glass, or safety glass, uses chemical processes and heat in its manufacturing. The heat and chemicals both provide the glass with enhanced strength. The term “safety” comes from the fact that it shatters to avoid damage or injury, but can you drill holes in it?

It is not recommended to drill holes in tempered glass because the glass is engineered to shatter upon impact, the drill’s impact would cause it to completely break and shatter. If any holes are needed, they have to be drilled in the glass before it is tempered.

Can You Drill Holes In Tempered Glass?

There are advanced techniques that are used commercially to cut or drill into tempered glass, such as industrial lasers.

These glass cutting equipment are not available in local shops and have a limited capacity as these are suitable for thin layers of tempered glass. To learn more about tempered glass and drilling in glass, keep on reading.

Why Can’t You Drill Holes?

In the case of thick and large glass products, cutting and drilling for the desired design and shape have to be done before the tempering. Once tempered, even a crack on the durable glass could cause it to shatter.

One of the purposes of tempered glass is its toughness, and when damaged, it shatters, thus avoiding bodily harm. It is commonly used in, among many other things, car windows, glass tables, cookware, and screen protectors.

Much of the glass used in museums, offices, restaurants, and malls are tempered. It is also ideal for entrance doors, fixtures, shelves, and tabletops.

Tempered glass is much less likely to break, but even if it does, the tempering process ensures that shards are minute and round, without sharp edges.

Before using it for various purposes, glass is always tested, which has to comply with strict specifications. Many safety codes around the world dictate using only safety glass.

Tempered glass cannot be cut or drilled. Various suggestions and recommendations have arisen regarding wet porcelain tile saws and diamond/carbide blades. Unfortunately, it just does not work that way.

Only that glass which is not tempered can be cut with home-tools and local shop equipment. Some have even reported cutting it, but obviously, the glass cut was not tempered and of questionable quality; otherwise, it would not have been cut.

What Is Tempering?

Safety glass uses thermal tempering as a process that rapidly cools or slakes the glass at a particular temperature using air jets. The glass is strengthened by compression, which occurs when the outer surface is cooled faster than the inside.

Also, the inside is stretched through this method and works well for regular glass thickness. Extra thick glass may be prone to fracture with such strength processing.

Without tempering, the glass breaks into jagged, sharp pieces that will almost certainly lead to serious injuries.

So tempering strengthens the glass, but there is another method of strengthening glass called heat strengthened.

Like the tempering process, it involves heat with temperatures reaching above 1,000 degrees Fahrenheit (538 degrees Celsius).

The only difference is the cooling process in the two methods. Tempered glass is rapidly cooled to create higher compression on the surface of the glass.

Tempering is also used as a heat treatment technique for metals, alloys such as steel or iron for strengthening. But unlike the effects on glass, the heat reduces hardness and increases ductility making metals brittle.

How to Know if Glass Is Tempered or Not

There are more than a few ways to find out if the glass in hand is tempered.

Safety glass is always sandblasted. This leads to smoother edges that are even and neatly finished. Non-tempered glass has edges that feel rough to the touch.

Additionally, manufacturers stamp the tempered glass with an identifying stamp that is binding. This helps the vendor by increasing sales as the customer is certified genuine material.

Thus, the signature and logo of the manufacturer are considered certified and thus make items easier to sell.

Another way to tell the glass type is by refraction. Holding a simple flashlight or a lighter can help determine the type of glass it is; two rays or flames means that it’s tempered.

Polarized glasses, too, help identify the tempered glass. Patterns appear as dark lines over the surface of the glass. This is due to the manufacturing process of compression.

Another indicating factor is finishing. Tempered glass is sometimes imperfect. It may have bends or wraps on it, but that is merely due to the heating process of tempering and not manufacturing defects.

The imperfections bend, or wraps are considered signs of authenticity and confirm material grade and quality.

Annealing Glass or Not – That Is the Question!

Annealing is the process of de-tempering glass. This means that the tempered glass is heated and chemically treated to reduce hardness, thus making it possible to cut or drill. It is the process of converting highly durable tempered glass to regular, simple glass that can break easily.

Once annealed, it also loses its safety characteristics. It can cause harm, so it’s much better to opt for ordinary glass that can be drilled into and cut into any shape desired. It is a better alternative because, firstly, tempered glass is not cheap.

Buying tempered glass to convert it to another type of glass is time consuming and certainly not cost-effective. Secondly, if at all working with glass, it makes much more sense to buy the required glass meant for cutting in the first place.

Drilling in Glass

Apart from tempered glass, other types of glass can be drilled or cut. Drilling requires careful steps, so caution must be exercised.

Protective gear is important for safety as this activity involves a drill and drill bits. For best results, especially smoother finishing, diamond drill bits should be used.

As mentioned, protection and safety should be a priority. Shards and other debris risk hazards to eyes so they should be shielded.

Glass dust can be dangerous to health, so a mask is highly recommended. Once the mask, goggles, and gloves are on, we are set to begin.

Always use a smooth, dry surface of the worktable that is stable. Avoid sloppy or wet areas. Place the glass on the working table with a rubber pad or cardboard underneath or attached to it to avoid slipping. Once this is done, a dent should be made in the area where the hole should be.

This is usually done with a low drilling speed. After that, remove the underlying or attached rubber pad or cardboard and drill the hole at a higher speed.

Apply some light pressure on the drill aimed at the dent and press the trigger. Always blow off any dust on the glass before examining and finishing up.

Also, ensure that the tempered glass will be the exact size and shape by measuring accurately. This can be accomplished with the help of a professional, which would also be a cost-effective way to license accuracy.


It is not possible to drill holes in tempered glass. The heat and chemical processes applied to the glass enhance its durability and strength. It is commonly referred to as safety glass, and many safety regulations and specifications require using it for various purposes such as entrances, doors, fixtures, tabletops, etc.

To identify tempered glass, manufacturers use stamps and stickers that mark it. It can also be recognized by using light refraction. Also, the finishing of the tempered glass is superior to regular glass. It also has imperfections that are caused by compression.

Annealing is a method of weakening and reversing the tempering process of the glass.

Related: Is Starphire Glass Worth It?

Hi there! My name is Jack and I write for ToolsOwner. I have a passion for everything related to tools and DIY projects around the house. You often find me in my workshop working on new projects.