Security paper, which are usually used in pasports, was produced by using a soluble thiocyanate and lead and was granted an initial patent in the early 20th century.
Examples of this kind of papers are those used for identification such as passports and , such as birth certificates and different types of academic and qualification certificates, as well as government documents, e.g., voting ballots and tax strips. According to the patent, the method by which security paper was produced involved using a soluble thiocyanate (such as ammonium thiocyanate) and lead, which could be used to create an insoluble salt, lead thiocyanate. An initial patent for the manufacturing process for security paper was granted to Robert E. Menzies and John E. Aitken in the early 20th century. 
