|34th PRS: Haze Paint Development|
HAZE PAINT DEVELOPMENT
...from an original article written by Dana Bell
Haze Paint has been an unguarded secret for nearly 60 years. It's a camoflage story that has "slipped throught the cracks" so to speak. Having never been listed in any Technical Order, and having been withdrawn from use before the appropriate revisions could be printed, Haze Paint has been something of a mystery. Since the peculiar properties of the paint made samples impractical, color chips were never circulated. Though it was the standard high altitude photo reconnaissance camouflage paint scheme from March to October 1942...most will not even be aware of its existence...or the fact that it was applied to nearly 130 photographic Lightnings! However, if any camouflage ever achieved invisiblity...Haze Paint was it!
It was in the summer of 1940 when a prominent paint manufacturer named Samuel Cabot contacted that Army about a new white paint with "unusual properties". It was a colloidal solution of zinc oxide in oil originally know by his stock number L 31340. These "unusual properties" were the grains of pigment themselves. They had a diameter below the wavelength of blue or violet light, which causes a high reflection in these color ranges. This is known as the "Tyndall Effect." This is what makes our skies blue, and the purple of our mountains majesty. Cabot theorized that by spraying this pigment over a dark blue or black base coat, only blue and violet would be reflected...with all other colors of the spectrum being absorbed by the dark base coat. Differing angles of reflection would change the rate of absorbtion and theoretically match the ambient sky color. Although "invisibility" was not promised under all circumstances, it was felt that under certain weather conditions and lighting situations, that this scheme would yield favorable results.
Cabot took his theories to the Massachusetts Institute of Technology which was involved with a number of military related scientific projects. Their engineers found his theories sound and hence urged the Materiel Division of the Army Air Corps to institute full scale testing. It would not be until late December 1941 that these tests would take place.
The December tests of the new paint scheme were performed using a Republic P-43. These initial trials were encouraging as to the prospects of utilizing this new pigment. In March 1942, Lockheed was given instructions to paint all of it's F-4 Lightnings in Haze Paint.
WHAT IS HAZE PAINT?
Haze Paint is a graded system of shadow shading or countershading with thicker coats of Haze Paint in shadow areas, to produce lighter colors. First, the entire aircraft was painted black. Then a light coat of Haze Paint was sprayed over the upper surfaces resulting in a very dark bluish color. A heavy spray of Haze Paint was applied to the under surfaces, particularly in shadowed areas. This heavy coat resulted in a graded finish that ranged from light blue to nearly white. Sides of the booms, fuselage and vertical stabilizers/rudders were mottled in a medium coat. Since Haze Paint was not a solid color camouflage scheme, and no equipment existed to control the precise application of the graded layers of paint...it fell to the "artistic" judgement of the aircraft painter. This resulted in many variations in the thickness of Haze Paint applied to different aircraft and as such all had differing reflectance. With only a loose standard to follow for application of Haze Paint to aircraft, many of the early airframes completed were unacceptable to AAF inspectors.
Painting in Haze Paint could only be done in daylight. During night there was not enough light to judge relative thickness. Haze Paint was an oil base requiring 12 hours to dry. As such it required another two to four man hours to remove accumulated dust and dirt in the finish. Fumes from the paint caused illness in some painting crews requiring hospitalization after an eight hour day of painting. Retouching chipped paint was nearly impossible to match, but even worse...as the paint finish weathered with age, the aircraft would progressively darken to it's base color losing any benefit from the Haze layer.
Typical Haze Paint scheme as it would be applied to the F-4A-1 of 1942.
Standard OD Paint scheme as it would be applied to the F-4-1-LO of late 1942.
In an attempt to solve some of these technical problems, Lockheed tried substituting a lacquer-based paint called "Cloudmist". This, however, was rejected by the AAF as being too rough of finish. "Ken-Haze", an enamel-base was also rejected by Materiel Command. With no suitable paint for it's F-5s, in October 1942, Lockheed was granted permission to paint it's PR Lightnings with the standard Dark Olive Drab/Neutral Gray pending resolution of the Haze Paint question. It was only a week later that the Proving Ground Command issued it's final report on Haze Paint, stating that it was only marginally superior in conditions of slight haze and that the standard Dark Olive Drab/Neutral Gray was just as good under all other conditions. At this Materiel Command recommended no further use of Haze Paint on PR Lightnings.
An example of poorly applied Haze Paint to a F-4A-1-LO of late 1942.
Seemingly, this would be the end of Haze Paint...but the AAF Director of Photography had convincing evidence as to the merits of the Haze scheme. Field units flying combat missions with aircraft finished in the Haze scheme reported the Haze camouflage as being considered extremely desireable. Even if it gave an unarmed recon pilot a slight advantage, it was considered a plus! In January 1943, following an internal policy debate, a directive calling for the application of Haze Paint was issued "until such a time as a more suitable type of haze paint is developed." Just such a replacement was at hand. Developed and tested at Lockheed, it was known as Synthetic Haze Paint!
SYNTHETIC HAZE PAINT
Recognizing that it would eventually be required to return to Haze Paint, Lockheed engineers turned to finding a suitable replacement. In January 1943, the AAF/Lockheed factory representative (an engineer from Sherwin-Williams) and an AAF 2LT met with Lockheed Vega engineers to develop a suitable replacement. Amazingly in flight test of aircraft finished in the oil-based Haze Paint, they were found brightly luminescent at altitudes above 20,000 feet! Since all testing of the Haze scheme had been done at low altitude and with no chase plane, it's no wonder the effect hadn't been noticed.
Lockheed developed a new blue base coat of Deep Sky tone which was designated "Sky Base Blue." Next the synthetic haze enamel, "Flight White" was tinted to a color named "Flight Blue." A F-5A Lightning was the first to receive this new scheme, with coats of Flight Blue in shadow areas and lighter coats of pigment on the sides and upper surfaces. Shading overall was very subtle and at first glance the aircraft appeared to be painted an uniform color.
Typical Synthetic Haze Paint scheme as it would be applied to the F-5C-1-LO of 1943.
With this new scheme applied, it fell to flight test to prove the new Synthetic Haze Paint formula. Flying the F-5A to 30,000 feet, the Synthetic Haze Lightning closed to within 1,000 feet of a Boeing B-17 Flying Fortress with six observers before being detected! Considered a triumph, both the Director of Photography and Materiel Command embraced the new scheme. By March 1943, Lockheed had standardized the Synthetic Haze Paint formula and scheme for all of it's F-5A/B Lightnings.
It's unclear exactly how many Lightnings wore Synthetic Haze Paint. Evidence suggests that Synthetic Haze Paint was not used after mid-1944, after which time, PR Lightnings which were painted were painted from RAF stocks in PRU Blue.
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