A burnisher is a rod-shaped steel tool used in copper plate printing for adjusting the tone, making corrections to the plate and various other purposes.
The shaft of a burnisher is gently curved towards a pointed tip and is shaped like the strip of cartilage in a squid with an oval cross section. The rounded part near the tip of this tool is rubbed against the plate to make the surface smooth and shiny. Machine oil is used for lubrication in this polishing process. It is used in various situations such as to increase the tone of an aquatint or mezzotint, to smooth a surface that has been shaved with a scraper, to modify minor details, and to do the final polishing work on a plate mark. Along with the scraper, it is a key drawing tool particularly in mezzotint where the burrs on the plate surface are shaved away with a scraper and then polished with a burnisher. A burnisher can also be used on its own. Variations in tone can be achieved by using it to plane off the burrs and polish the plate. The difference can be remembered as follows: The scraper is used to shave and scour while the burnisher is used to smooth and polish.
There are several types of burnishers. Some have a wooden handle, others are made entirely of metal and come with a needle or scraper on one side. Being a polishing tool, to prevent it from rusting, it is best to wrap it in a piece of cloth soaked with machine oil when storing.
Burnishers can be purchased at art supply stores that handle printing supplies.