As the name suggests, gunpowder vans were used to transport gunpowder and other explosive materials by rail. The earliest examples started to appear in the mid-1880s and later versions could be seen on the network well into dieselisation. They were used for the transportation of ordnance but also saw regular use around quarries and mines.
Fundamentally, gunpowder vans had much in common with regular covered wagons but with many features added to ensure sparks were kept at bay. These included a steel body design with wood lining and lead sheeting as well as the use of brass or copper fixings, especially around the door mechanism.
The GWR telegraphic code for a gunpowder van was 'Cone'.