Unexploded Dynamite Detonations: Footage and Aftermath from Bridges to Backyards

Uncover key developments related to Unexploded Dynamite Detonations: Footage and Aftermath from Bridges to Backyards in this special report.

The stability Nobel achieved was temporary. Commercial dynamite was designed for consumption within months of manufacture, not preservation across decades. When cardboard boxes of cartridges sit forgotten in unheated sheds or humid basements, the kieselguhr absorbent slowly degrades. Moisture displaces the nitroglycerin, forcing the oily chemical to leach outward through the waxed paper wrapping. Explosive technicians call this "sweating."

Sweating dynamite represents an extreme emergency. The leaked liquid pools at the bottom of storage boxes, penetrates wooden floorboards, and coats exterior wrappings in pure, unbuffered nitroglycerin. In this state, an accidental nudge from a broom handle delivers enough kinetic force to trigger high explosives chemistry.

Freezing temperatures make the problem worse. Liquid nitroglycerin freezes at roughly 13.2°C (55.8°F). When cooled, it forms dense, jagged monoclinic crystals. Crystallized nitroglycerin danger stems from internal friction: shifting the stick causes rigid crystals to grind against one another, generating microscopic heat spikes that detonate the entire mass. The homeowners in Valley Glen and Arizona who placed sweating sticks into freezers were operating on a lethal misconception. Chilling old dynamite does not preserve it; freezing turns a hair-trigger compound into an immediate bomb.