In 1976 the leadership of the Military Airlift Command (MAC) were getting after-action reports from joint training exercises that the white top/gray color scheme of the Lockheed C-141 Starlifter fleet made the aircraft easy to spot even at long distances. At the time, the Aeronautical Systems Division (ASD) of the USAF had been testing a camouflage called Mask-10A that was IR-reflective and was being test-flown on the A-10. In July 1977 MAC asked that the Mask-10A be tested on the next Starlifter up for programmed depot maintenance. Testing showed the two-tone gray scheme added too much weight to the aircraft, absorbed dirt and grease too easily (it had a rough sandpaper like texture) and was difficult to wash. The aircraft had to fly in the Mask-10A scheme for two years before getting repainted in the camouflage scheme MAC ended up selecting, European One (two shades of green and dark gray).
At C-141 Heaven there is a great page of the actual aircraft as well as numerous pictures showing it in the Mask-10A scheme.
Source: C-141 Starlifter in Action (No. 1215) by John Burford. Squadron Signal Publications, 2009, p30.