International Journal of Wildland Fire International Journal of Wildland Fire Society
Journal of the International Association of Wildland Fire

An experiment to test the potential for glass fragments to ignite wildland fuels

Klaus-Peter Wittich A C and Tanja Müller B

A Agrarmeteorologische Forschung, Deutscher Wetterdienst, D-38116 Braunschweig, Germany.

B Institut für Geoökologie, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.

C Corresponding author. Email:

International Journal of Wildland Fire 18(7) 885-891
Submitted: 6 May 2008  Accepted: 15 October 2008   Published: 27 October 2009


It is current opinion that glass fragments can serve as an ignition source for grassland, bush and forest fires by focussing sunlight. In order to check the validity of this assumption, ignition experiments were conducted in the open over six litter samples taken from forests in northern Germany. Of several glass fragments, the five bottle bottoms best focussing sunlight were installed 15–50 cm above the litter materials. We found that one bottle bottom was able to slightly char spruce needles, beech leaves and blades of grass. Although this particular bottle bottom let the temperature increase up to 327°C, flame formation did not occur. A secondary (but more realistic) experiment with a glass-bottle bottom lying on the litter led to a maximum temperature of 82°C in the space between the litter and the glass fragment.

Additional keywords: burning-glass effect, ignition experiments, light focussing.


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