It is possible to conclusively link a photocopied document to a specific photocopier. The scientist will look for marks on the photocopy originating from specks of dust or scratches on either the glass platen or the photocopier drum.

Some of these marks are transient – cleaning the glass platen will remove dust and dirt. If the marks originate from damage to the internal mechanism they may not appear on every copy, and may appear in slightly different places.