Once the sheet is manufactured, an uncoated paper surface can be coated with white clay materials. The clay gives the paper a smooth feel by filling microscopic valleys on the paper surface.
The coating also limits the absorption of inks into the paper. Because the inks stay on the surface of the coating instead of soaking in, the ink appears richer, sharper and glossier. Text, images and photos stand out more than on uncoated. However, writing and ballpoint pen inks take longer to dry on coated paper and smudge easily. Less ink is needed on coated papers.
Coatings are offered in a range of reflectivity values including dull, matte, silk, satin or glossy. Reading text is easier when printed on dull or matt finishes. After printing images on dull or mat stock, a varnish can be applied to the picture areas to add gloss and make the pictures pop.