# Spark Plugs and Broken Glass

**URL:** <https://boards.straightdope.com/t/spark-plugs-and-broken-glass/120987>\
**Category:** Factual Questions\
**Created:** [July 26, 2002, 7:48pm UTC](https://boards.straightdope.com/t/spark-plugs-and-broken-glass/120987 "2002-07-26T19:48:16Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Hesher666](https://avatars.discourse-cdn.com/v4/letter/h/4bbf92/32.png) [@Hesher666](https://boards.straightdope.com/u/Hesher666)\
**Post date:** [July 26, 2002, 7:48pm UTC](https://boards.straightdope.com/t/spark-plugs-and-broken-glass/120987/1 "2002-07-26T19:48:16Z")

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Ok, I just sent this off to Cecil, but thought that I might try here as well:

```
 A few years ago I talked to a woman who's car was broken into. She told me that the thieves broke the window with porcelain from a spark plug. She said that even a small amount of spark plug porcelain could punch a hole in a window when thrown against it. I wasn't sure about this, so I tried it on a junker car in my possesion. I broke an old spark plug, took a pebble sized piece of the porcelain and threw it against one of the windows. Sure enough, it poked a nice hole in the window with no trouble. "Wierd." I thought, and then forgot about it for a while. But recently I started wondering why that is, and if it would work on other types of glass (house windows, safty glass). I certianly don't want to try that, but I imagine that the type of glass and thickness would vary the results. What is it about spark plugs that make them good for this?

```

-Jeff

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**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\
**Post date:** [July 26, 2002, 7:51pm UTC](https://boards.straightdope.com/t/spark-plugs-and-broken-glass/120987/2 "2002-07-26T19:51:00Z")

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This was asked about a month ago. Search in **GQ** for “spark plugs” and you should find it.

Welcome to the **SDMB**.

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**Author:** ![sailor](https://avatars.discourse-cdn.com/v4/letter/s/a587f6/32.png) [@sailor](https://boards.straightdope.com/u/sailor)\
**Post date:** [July 26, 2002, 8:16pm UTC](https://boards.straightdope.com/t/spark-plugs-and-broken-glass/120987/3 "2002-07-26T20:16:01Z")

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[http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=120160](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=120160)

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**Author:** ![Hesher666](https://avatars.discourse-cdn.com/v4/letter/h/4bbf92/32.png) [@Hesher666](https://boards.straightdope.com/u/Hesher666)\
**Post date:** [July 26, 2002, 8:41pm UTC](https://boards.straightdope.com/t/spark-plugs-and-broken-glass/120987/4 "2002-07-26T20:41:10Z")

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Wierd, maybe I did the search wrong, because I did take a shot at it before asking. Oh well, sorry about that.

-Jeff

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**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\
**Post date:** [July 26, 2002, 9:13pm UTC](https://boards.straightdope.com/t/spark-plugs-and-broken-glass/120987/5 "2002-07-26T21:13:06Z")

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The usual novice error when searching (not to jump to conclusions, but just so you’ll know to watch out for it) is to not change the date range from the default “yesterday” to a more likely option. 🙂