Burnishing is a means of corrosion protection. In contrast to other techniques, no additional layer is applied to the metal during burnishing, rather an anti-corrosive, mixed oxide layer of FeO and Fe2O3 is created on the surface. During the burnishing process, the colour of the surface changes to black or dark blue.
In order to achieve an even surface finish, the metal must first be treated with a degreaser and possibly also with fine steel wool (grit 00). Afterwards, the actual burnishing process can be started at a temperature of 20-30 °C. The finished workpiece should then be oiled overnight to stabilise the burnish.