High Quality Content by WIKIPEDIA articles! Plastic armour (also known as plastic protection) was a type of vehicle armour originally developed for merchant ships by Edward Terrell of the British Admiralty in 1940. It essentially consisted of small, evenly sized rock or stones in a matrix of bitumen. It was typically applied as a casting in situ to existing ship structure in a layer of about two inches thick or formed in equally thick sections on a half inch thick steelplate for mounting as gun shields and similar.