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The basis for determining whether a printed piece is authentic requires a basic knowledge of the characteristics that distinguish one printing process from another and knowing when those processes would have been employed. Generally, no one who intends to counterfeit a printed piece, in order to make his efforts profitable, could use the same identical procedures and process as done with the original. It is almost impossible to perfectly replicate a printed piece wing to the fact that certain materials and tools used in the printing or graphic arts trades have had a limited existence. Knowing the historical background of these resources, understanding of the limitations of the craftsmen and the developments in the field over the last 50 to 60 years makes it possible for one to determine how and when something was printed. Some of these tools that were once almost exclusively sold to the trade ar now common household items. The age of low-cost home computers, computer printers and scanners has opened a whole new and lucrative market for those who see an opportunity to imitate the works of early craftsmen and artists, cashing in on the buyer's naivety.