It was also used for counterfeiters, swindlers and coin forgers during the Middle Ages. Tempering was originally a process used and developed by blacksmiths (forgers of iron). Although the forgers attempt to capture Tintin, the police arrive and arrest the criminals. Scarabs are a common counterfeit product of present day forgers. Japp reveals that the Crofts are known forgers. Jean de Sperati is among the master forgers in the history of philately. Stamps produced by famous forgers have become collectibles, as well. Late that night they went to Tour Saint-Bernard where the forgers of assignats were jailed. Coin forgers were boiled to death in 1452 in Danzig and in 1471 in Stralsund. Boileau notes that some professions were also open to women&colon; surgeons, glass-blowers, chain-mail forgers. The stamps have been the target of forgers, including Erasmo Oneglia and A. Alisaffi. This indicates the potentially lucrative payoff for forgers. His own work became valuable as well, which in turn attracted other forgers.