A clear coating provides protection from smudging, fingerprints, and water droplets. It does not improve the permanence of the print because most fading is due to visible light. On some material, such as canvas, coating can render a print water-resistant, allowing it to be framed without glass.
After printing, a clear coating is applied to a print to protect it from smudging or smearing from water or fingerprints. Coatings usually do not increase the fade resistance of a print, however. Coating a canvas will make it waterproof so that it does not have to be mounted under glass or Plexiglas.