Early engraving methods began with wooden blocks and moved on to copper plates in the 15th century. Skilled artists and artisans carved artwork into the plates using a burin, a sharpened steel bar mounted in a wooden handle.
Steel replaced copper as the engraving medium in the early 19th century. The new medium's harder surface complicated the engraver's work. Steel's durability as a printing medium and its ability to hold very fine detail gave it advantages copper could not match.
Engravers covered a steel plate with a mixture of wax and coal tar and transferred an image from tracing paper. They etched the image with engraving needles and treated the plate with acids. Some engravers specialized in types or parts of illustrations.