Abstract: The present invention relates in one aspect to a method of manufacture of a security thread suitable for use in security articles including security paper such as that used for banknotes. In the method a magnetic metal is deposited on a film of polymeric substrate as the substrate passes through a solution containing the magnetic metal and a preparatory operation is carried out on a surface of the substrate prior to immersion of the substrate in the solution. The preparatory operation ensures that magnetic metal is deposited on the substrate in a pattern such that when the security thread is produced from the film by cutting the film the magnetic metal on the security thread has a specific pattern and provides both a visually discernible security feature and a magnetically detectable security feature.