Paper with a clay or other coating applied to one or both sides is coated paper. The coating can be dull, gloss, matte, or other finishes. Coated paper generally produces sharper, brighter images and has better reflectivity than uncoated paper.
Coated paper typically is smoother and has better ink holdout — is less absorbent — than uncoated paper making it more suitable for certain types of overprint finishing techniques such as flood or spot coating with varnish or other finish coatings. The coating may be applied while the paper is still going through the papermaking machine or it may be applied afterwards. Clay, latex, and other substances are mixed to create the coating.
Photo papers for inkjet printing typically have UV coatings.