From Naval Aviation News, January 1957:
"Certain new production aircraft are coming off the line with gray or light green instrument panels. Black instruments against a gray panel make for reading ease.
Tests by the Air Crew Equipment Laboratory, Naval Material Center, proved the value of contrast. Eleven pilots flew F9F-6 Cougars with instrument panels painted with varying shades. Light color backgrounds proved a complete success."
The short article included a black and white photo of an F9F-6 instrument panel with the caption “Cockpit panels will be painted medium gray during aircraft O&R repairs”. There was also a black and white picture of five squares of varying degrees of gray for five different aircraft, with No. 70 being something like light gull gray and No. 74 being a charcoal, captioned “Paint on Plane 72 was the pilots’ choice”, 72 being halfway between the lightest and darkest in shade.
It should be noted that on 25 March 1954, BuAir had already directed that a nonspecular Dark Gull Gray finish be applied directly over the previous Zinc Chromate green or Interior Green surfaces of all Navy and Marines Corps aircraft cockpit interior spaces, buldkheads, floors and instrument panels except for nonspecular Black for canopy framing and horizontal surfaces above the top of the instrument panel that could cause sun or light glare. Presumably there was some rationale for the color choice and all new production aircraft were already being painted that way.
Some possibilities: 1. That article had been hanging around without being published for some time (years), 2. The word hadn’t gotten to the Naval Air Material Center that a decision had already been made, 3. The word hadn’t gotten to all the manufacturers to paint instrument panels dark gull gray, 4 “Medium Gray” was an editor’s substitution for the more accurate but less well-known nonspecular Dark Gull Gray.
My conclusion - don’t fret over color choices and don’t be too sure that someone’s color choice is wrong…