Glaze
In painting a glaze is a transparent layer of paint brushed over a dried underlayer. Generally associated with oil painting, glazes can also be applied on top of each other to create a feeling of depth and luminosity in the work, also protecting the paint and adding richness to the colour. In ceramics it is a glassy coating, either transparent or coloured, applied before firing to give a water-resistant, lustrous surface.
Colley Cibber
attributed to Benjamin Rackstrow (or Rackstraw)
circa 1740
NPG 1045
Tom Cribb
by Unknown artist
circa 1810-1815
NPG 5812
Sir Henry Wylie Norman
by Unknown photographer
mid-late 1850s
NPG x21537
William Booth
by Unknown artist
circa 1900
NPG 5814
Sir Leslie Stephen
by George Charles Beresford
1902
NPG x12918
Susie Cooper
by Susie Cooper
circa 1933
NPG 6375
Eartha Kitt and an unknown woman
by (Edward) Russell Westwood
1951
NPG x35237
Christine Keeler
by Geoffrey Davien
1964
NPG D2726