The Pendulum Shed ...
Please refrain from placing TBs within this Cache
The Ballistic Pendulum in this shed was used up until 1983 to calculate the explosive strength of the powder or gel produced on the site. A charge of explosive was placed in a cannon, which was then pushed up against the cavity in the pendulum. The explosion would cause the pendulum to swing, while a pointer would record the force of the blast on a scale.
The Nitroglycerine production area came to be known as Klondyke by the workforce. Materials, including glycerine and glycol plus nitric acid and sulphuric acid pumped from the middle valley were mixed and then tested to establish their stability. What is now the bird hide once housed a series of 7 settling tanks where excess Nitroglycerine was removed from the washing water. Further ingredients were then added to the mixture to produce powder or gel based explosives, which were then transported to the middle valley for catridging. The cartridges were passed through liquid wax for sealing from moisture, before being stored in secure magazine buildings. Many of the factory’s buildings had safety features such as lead flooring, reducing the risk from sparks.
Production of complex “Permitted Explosives” peaked in the 1970’s, when the site was considered the most sophisticated operation of its kind in the world. Work finally ceased in 1995 following a decline in the demand for Nitroglycerine based explosives. The area was decontaminated and decommissioned before being handed over to the NWWT in 1998.
Gwaith Powdwr is a post-industrial nature reserve owned by the North Wales Wildlife Trust and located in Penrhyndeudraeth near Porthmadog. The site — formerly an explosives manufacturing works — covers an area of 28 hectares spread over three valleys of heath, scrub and woodland habitat.
Production of explosives at the site dates back to 1865 and the works there were destroyed by a massive explosion in 1915. In the 1920s the site was acquired by Cooke’s Explosives Ltd, which was, in 1958. Production finally came to an end in 1995 and three years later donated the site to the North Wales Wildlife Trust.
Cache placed with the kind permission of Rob Booth,Swyddog Tirluniau Byw (Conwy a Gwynedd)/ Living Landscapes officer(Conwy and Gwynedd)