Why Does Spark Plug Porcelain Break Glass?

By Staff WriterLast Updated Mar 25, 2020 10:11:59 PM ET

Tiny shards of spark plug porcelain have small hard points which allow them to easily find a breaking point in glass. They can also be used to break the side window of vehicles. Spark plug porcelain fragments are sometimes referred to as ninja rocks because of their ability to break glass with ease.