Plates can be mechanically roughened, but the classical way is to rub fine metal filings over the surface with a piece of glass; the finer the filings, the smaller the grain of the surface. Mezzotint is known for the luxurious quality of its tones: first, because an evenly, finely roughened surface holds a lot of ink, allowing deep solid colors to be printed; secondly because the process of smoothing the texture with a burin allows fine gradations in tone to be developed.