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September 18, 2008

Beauty in destruction

Broken glass can tell a number of stories to the investigator - if they know what they are looking at. Glass is a strange material, technically it is a super-cooled liquid at normal temperatures. It is also a very poor conductor of heat or cold and when subjected to heat from a fire, the heat is distributed unevenly and eventually breaks the glass. Normally the edges of glass broken in a fire by heat will have smooth shiny edges and artistic wavy curves along the break. Occassionally though, something else happens - then you see some interesting marks and the picture here is one such.

Uneven heating in the window caused this glass to break under the stress created by different parts of the glass trying to do different things at the same time.

OK, so I'm an anorak when it comes to looking at things like this. But you have to admit that it is interestingly beautiful - a fern leaf in the glass created by forces we still do not entirely understand. Fascinating.

Posted by The Gray Monk at September 18, 2008 08:17 PM

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I think it's lovely. And you know what? I find it amazing what you can learn from the way the glass breaks as far as what the fire was doing. More! more!

Posted by: Da Goddess at September 19, 2008 09:14 PM

I agree. Beautiful. Wow.

Posted by: vw bug at September 19, 2008 10:01 PM

Very pretty - I'm wondering what the petrol on water effect is in the photo - not traces of accelerant, I assume?

Posted by: Postulant at September 20, 2008 10:43 PM

Condensed pyrolysis products - oily soot to you and I! It condenses out of the smoke, which is essentially unburned fuel, on any smooth surface which is cooler than the smoke plume. You find it on walls, ceramics and glass. If touched by a flame it burns off leaving a white-ish 'ash@ trace behind.

Posted by: The Gray Monk at September 25, 2008 05:16 PM