Ive been told that the cermaic part around a spark plug vibrates a certian way when it hits glass (more specifically a car window), causing the glass to break.

So all you would have to do is get an old spark plug.....break a piece of the ceramic coating off....and toss it at a car window.

Anybody want to confirm?

it doesnt "vibrate" at all, it just happens to be harder than glass

It will cause the glass to slowly shatter but remain together. You can actually sit and hear it cracking. Took about 15 minutes for a rear window to completely spider web and then it just fell apart.

I carry a folding screwdriver in my pocket, I can take the small screw driver and tap the window. sit back and watch the fun.
Or I can take the punch tap the window in a corner near the edge and it will just shatter.
When I need to get into a car I don't have time to try and find a spark plug

btt

Quoted: I carry a folding screwdriver in my pocket, I can take the small screw driver and tap the window. sit back and watch the fun. Or I can take the punch tap the window in a corner near the edge and it will just shatter. When I need to get into a car I don't have time to try and find a spark plug

Are you a repo man?

ARH

It's just harder than the glass, so it breaks through easier than softer materials (like regular steel) would. It's not a mystery. A solid piece of quartz or a really big diamond would work too, but a spark plug is cheaper and easier to find.

......
If you want to break glass silently, you first heat a small spot with a mini-butane torch, and then you dab the hot glass with a (cool) wet rag.
------
But on a car window, the whole window is then ruined--because the cracks may only start out in a small area that you heated, but they will spread on their own over the whole window within a few minutes.
~

I'll confirm this one, I've done it 10-15 times.

Im not sure technically WHY this happens, but it doesnt need to be thrown extremely hard, and it will punch right through glass only taking out the glass in the shape of the object you threw, spider cracking the rest.

I used to do it in auto-tech in highschool. We would knock the ceramic part of a spark plug off an old engine and see what we could ricochet it off of to still break a window.

I hold the record for skipping one off the top of a mini-van, then it flew threw the driver side window of a mid 90's chevy truck and out the passenger side window.

Yes, it works.

Quoted: It's just harder than the glass, so it breaks through easier than softer materials (like regular steel) would. It's not a mystery. A solid piece of quartz or a really big diamond would work too, but a spark plug is cheaper and easier to find. ...... If you want to break glass silently, you first heat a small spot with a mini-butane torch, and then you dab the hot glass with a (cool) wet rag. ------ But on a car window, the whole window is then ruined--because the cracks may only start out in a small area that you heated, but they will spread on their own over the whole window within a few minutes. ~

Never heard that before. Thanks for the info.