How to Pick the Right Type of Glass

It was 1:37AM in downtown Washington, DC around a place called Adams Morgan.  A notorious place for college students and young professionals alike to partake in drinking copious amounts of booze and forgetting the stress of the daily city grind.  There is also a massive police presence because of incidents that occur with so much drinking.  On this particular night I saw a young drunk male come out of a bar, and stagger onto the street.  He stumbled right into a police car, which currently did not have any police officers sitting inside.

I wasn’t sure if it was his own decision or influenced by his other drunk peers, but this is when he decided to climb the hood of the police cruiser, yell out some incoherent battle cry, and perform a giant front kick into the windshield.

I thought for sure he’d break the glass, get his leg stuck within the police car, with shards of glass stuck to his leg.  I was hoping to see some blood.

None of that happened.

As he kicked the windshield, the glass kind of wobbled into the vehicle, and bounced right back, sending the unbalanced drunkard falling off the hood of the car, and onto the street. His cohorts helped him off the ground and they hastily retreated to another corner of the street.  This is what the windshield looked like:

Tempered glass on windshields

Why didn’t the glass shatter like I expected?

It wasn’t until studying for the CISSP exam did I discover all the different types of glass used for windows, vehicles, data centers, and office buildings.

In this post we talk about some of the main types of glass related to the physical security of the CISSP domain.

Tempered Glass

The police windshield above is made out of tempered glass, as is all other vehicle windshields.

When hit by something, tempered windshield glass does not break into large sharp pieces.  Instead it disintegrates into small cubic pieces that are not sharp.  Isn’t that a relief? Imagine being in a head-on car accident, and have tons of sharp glass fly at you at the same time?  Scary.

Tempered glass is made differently that other glass.  It is toughened on the exterior using compression, and dense on the inner portions.  This makes the glass tough to break, and even if it does, the pieces are not sharp.  An extended heating and a quick cooling process is used to make this type of glass.

EXAM TIP: Remember the number one asset to secure is human life.  We should build all our security plans around protecting humans first, and data second.  Even in the case of the drunk guy kicking the police windshield, no matter how much of a jackass he may be, you gotta think about how to protect his life first.  

Wired Glass

Wired glass is weird.  There are literally wires between the top and bottom of the glass.  If you strike it, the whole thing won’t shatter, as the wires will still be holding it somewhat together.

Wired glass can be found in office doors and specifically prisons.  Can you imagine why?  Even if prisoners break through the glass, they still have a wire barrier to get through.

In terms of security, this also provides another layer of protection when protecting information security in places such as data centers and LAN rooms.

Close-Up

Wired glass on prison doors

Laminated Glass 

This one is important to remember.  

Laminated glass is what we see when walking the sidewalk and window shopping.  They are used for stores that are on the street level, and provide protection for doors, windows, and other glass barriers.

The definition of lamination deals with layers.  This is how you can remember how laminated glass is made.  Imagine a layer of plastic, with a layer of glass on top, and a layer of glass on the bottom, like a sandwich.  This is how laminated glass is made to resist breakage.  The middle plastic part makes it tougher.   

Street level laminated glass

Bullet-Proof Glass

This is obvious, this type of glass can take the impact of a high-velocity piece of metal such as a bullet.  Guess where these are used? BANKS, and other high security areas.

If you’re a CISSP that has to consider bullet-proof glass when planning your physical security, you probably have a pretty important security job.  Don’t take it lightly!

Acrylic Glass

There is a problem with acrylic glass: if it burns, it produces toxic fumes.  This would not be a good idea for glass within a confined or internal setting with people around.

Given this fact, if it is still used in environments, it is going to be very tough to penetrate or destroy.  It is stronger than normal glass because of something called poly carbonate.  It is the polycarbonate that makes acrylic glass so resistant to damage.  

You have to weigh your risks, do you want a strong glass that is highly resistant to breakage, but at the same time, toxic to humans if burnt?  As a CISSP, preserving human life is the number one importance, and data is second.  You’ll have to take these two points into consideration when choosing acrylic glass.

  • Ahmed Khatib

    Beautifully explained! I think you missed on Acrylic types of glasses!

    • studynotesandtheory

      Thanks Ahmed! I just updated the post to include acrylic! Let me know if I missed anything!

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