Just to finish off the brief introduction to printing styles ...
This means that the image sits on the same level as non-image areas and takes us up to modern lithographic printing.
Invented in 1798 by Aloys Senefelder, lithography is based on the principle that oil and water do not mix. The word “lithos” means stone and the image was originally drawn in wax (or similar) on to the surface of stone. The surface is then chemically treated to fix the image, and the stone sponged with water. The waxy drawing repels the water and when oily ink is then applied, it will fix to the drawing only.
Originally, prints were distributed to homeworkers to be hand coloured.
However, the lithographic process meant that colours could be laid on top of one another. A different stone is used for each colour and the process was called chromolithography, developed in the 1840s.
Early in the 20th century the images were transferred to zinc plates. By World War II, the process was called offset lithography, using 4 metal drums – each for a separate colour – and combining them to obtain all colour combinations.