How does a spark plug break glass?

I heard from a number of people, and on TV that if you strike a spark plug on a glass window (ie. a car window) it will shatter. How does this happen?

8 Comments

WellBalanced
on February 6th, 2012

Hi Troyboy!

Automobile glass, with the exception of the windshield, is tempered glass. This is often referred to as a type of “safety glass”. Tempering is a glass production process that creates glass that is very strong against blunt force. However it will shatter into small non-sharp pieces if fractured by a sharp object. A car’s windshield is laminated and will not shatter in the same fashion.

Tempered glass is often used in other applications as well. Computer Monitors, for example, are generally tempered glass.

http://auto.howstuffworks.com/question50...

There is nothing really special about a spark plug that would break the glass other than it has a small area of impact that could fracture the glass. Truthfully, any small tool will do it, particularly if it has a pointed end. They actually make small escape tools you can carry on your key chain or in your glove compartment to break the glass in an emergency…

http://www.storesonline.com/site/529271/...
http://www.lifehammer.com/

I hope that answers your question.
ChickenLicken
on February 6th, 2012

Throw it hard enough.
BlindPoet
on February 6th, 2012

I have tried it… my results… it does nothing unless you use force.
Wildthing
on February 6th, 2012

You can use that broken shard of a spark plug insulator (the white part) as a glass-cutter.
DarkDesire
on February 6th, 2012

car glass is shatter proof
JetSki
on February 6th, 2012

Throw it like a rock.
Eli
on February 6th, 2012

Its like a rock. Throw it hard enough and it will do the job.
The great
on August 8th, 2011

Your all wrong

If your going to throw the White ceramic coating around the spark plug
Then don’t do it on the front window of a car it won’t wrk.

Any other window it will.

Ceramic is very hard.harder than glass this is why it punches through it I’m not to sure on the scale of hardness but I’m sure it’s not to far away from diamonds.

Diamonds cut glass with ease and if you was to just flick a diknd at tempered glass it would shatter into Millinsof pieces.just try it I’m sure if u live in London there might be a few windows left unless all these losers have done them all