Burnishing (pottery)

Burnishing is a form of pottery treatment in which the surface of the pot is polished, using a hard smooth surface such as a wooden or bone spatula, smooth stones, plastic, or even glass bulbs, while it still is in a leathery 'green' state, i.e., before firing. After firing, the surface is extremely shiny. Often the whole outer surface of the pot is thus decorated, but in certain ceramic traditions there is 'pattern burnishing' where the outside and, in the case of open bowls, the inside, are decorated with burnished patterns in which some areas are left matte.

This technique can be applied to concrete masonry, creating a polished finish.

Burnishing can also be applied to wood, by rubbing two pieces together along the grain. Hard woods take the treatment best. Burnishing does not protect the wood like a varnish does, but does impart a glossy sheen.

If one wood has a dye in it or is colored in some way, it may rub off onto the other wood. Burnishing can also apply to relief printing.

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Wikipedia