NIVO, abbreviated from Night Invisible Varnish Orfordness (or "Night Varnish Orfordness"),[2] was a dark grey-green overall finish applied to British night bomber aircraft in the inter-war period (1918–1939).

Developed in 1918 by the experimental station at Orford Ness, as a low-visibility colouring for the Royal Air Force it had a sheen to match that of open water on a moonlit night.

By the mid-1930s, tests had determined that the varnish was too reflective when searchlights were shone on it.

[3] NIVO was phased out in the late 1930s, and had been discontinued by the time of the arrival of the new British medium bombers – the Vickers Wellington, Handley Page Hampden and Armstrong Whitworth Whitley.

NIVO is covered by Federal Standard 595 colour FS:34096[4][5]