A tympan is made from a soft material (such as parchment, leather, paper, rubber). It is used for letterpress printing and covers the the platen or printing cylinder while printing. It provides a necessary flexibility and can also be used to adjust the printing pressure. The tympan can be mounted permanently on the platen or printing cylinder or it mounted to a frame, which is then put between the platen and the forme while printing.
A simple galley proof press with a paper tympan