Aircraft radomes have often appeared in a different colour from the surrounding airframe because their materials and coatings must let radar signals pass through with minimal distortion. A retrospective explainer by The Aviationist traces the familiar black nose cones on older military aircraft and airliners to early protective finishes, including rubber and neoprene, and later black paint. Modern composites and coatings allow closer colour matches, but radomes can still look different from the fuselage.
A radome shields the radar antenna from weather and impact while providing an aerodynamic cover. Early designs used materials such as laminated wood and fibreglass; later versions adopted composites. The outer coating also has to withstand rain, hail, dust and other wear without compromising radar performance. The Aviationist describes carbon-based coatings that helped dissipate static electricity, as well as black paint that avoided metallic components found in some paints of the period.
The colour difference is not always simply a matter of paint choice. Radome materials may differ from those used elsewhere on the aircraft, and restrictions on primers and coatings can leave a visible contrast even when the finish is intended to match. Weather and impact damage can also wear away the surface.
FAA Advisory Circular AC 43-14 advises that radomes should pass transmitted signals and returning echoes with minimal distortion and absorption. Excessive, uneven or metallic paint coatings can affect that performance, making coating thickness and repair condition operational concerns as well as cosmetic ones.