The design was drawn onto a litho stone
, etched with acid, transferred to the machine stone, further treated and eventually washed with water and transferred to the printing press.
Peter McCue who had in his possession a litho stone
used in the printing of original nursing licenses when it was known as "The Colorado State Board of Nursing Examiners." It was Mr.
Above, A stonehand at work for Walsall Security Printers, demonstrating how stamps were printed in the early days on a litho stone
. Left, The tiny 'W2' in the bottom left hand corner of the pane of six stamps is the collector's indication that they have been printed by WSP.