Above: Karl printed "Karl Martz (KM) Potter" at the top of his stationery in the late 1930's. Another style of stationery is shown at left (top, reduced to black and white).

He also did the self-portrait at lower left.

These are "linoleum cuts" (see Graphic art by Karl Martz). A letter Karl wrote to his grandson Eli Martz in 1995 included this description of linoleum cut prints:

Wood block prints are made with a similar process, except using a block of wood for carving the image, instead of linoleum mounted on a wood block. Linoleum was used because it provided a smooth flat surface free of the texture of wood, and it is easier to cut than wood, lacks the grain of wood, and doesn't splinter or split.