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F4U-1, Salmon vs. Zinc Chromate Primer

July 23, 2014 in Aviation

Dear all,

my next project: a Birdcage. I intend to build a badly worn and weathered exemplar and I already investigated historical pictures of it – of course in black and white.

Regarding paint work, some sources talk about salmon colored others about classic yellow-green zinc chromate primer for the early aircraft, later ones were prime coated in zinc chromate only. The pictures attached were taken by Jay Cochrane of a plane found in Lake Michigan in 1995, and finally pulled to the surface on Nov 8,2010. It crashed on June 12 1943. To me it looks as if both coats are on, the green and the pinkish one.
So why would one use two different colors for two different prime coats, one made of zinc chromate the other of zinc chromate with some red pigment added?
Well, in order to ensure that paint has covered every piece of the surface, I guess. I assume that the green one is below the red one. The fact that the red primer survived inside but is almost completely lost outside of the wing might support the theory.

That much about detective work. Can anyone add facts?

All the best and looking forward to your comments.

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9 responses to F4U-1, Salmon vs. Zinc Chromate Primer

  1. Hi Halvar,

    No expert, but it looks like a combination of red lead primer with yellow zinc as well. I think it was a practice to factory-dip all ferrous metal in red lead as it often sat in rail yards etc for some time exposed to the weather, before the raw material was shipped to the aircraft factory.

    A control coat of zinc (yellow or green depending on manufacturer) was then sprayed as a control coat prior to assembly of sub-units (electrical, hydraulic).

  2. Thank you for posting. I think it gives a lot of us a new look at the weathering of models.

  3. Interesting….it would appear (to me, anyway), that it solves ONE dilemma- it doesn’t matter which primer color you opt for…apparently they’re BOTH “correct”.

  4. “Salmon was a pale pink-colored chromate primer used by Vought in production of the F4U Corsair. It was produced by mixing Indian Red pigment with raw Zinc Chromate primer.”

    “As mentioned before, early production Corsairs had their interior surfaces in areas other than the cockpit covered with Salmon primer. This colour mixture was used relatively long into Corsair production. It would seem that all F4U-1s and a number of early F4U-1As were finished this way.

    Somewhere during the production of F4U-1A model Vought discontinued the use of Salmon primers and switched to Zinc Chromate Yellow with cockpits in Interior Green.

    In the engine cowling area, Vought adhered to the practice of painting its inner surface the same colour as the underside, ANA 602 Sky Gray on early F4U-1s, ANA 601 Insignia White on F4U-1As.”

  5. Hej Martin. Many thanks. I know that article, but actually the pictures I posted demonstrate that Vought at some time used both paints one over the other or at least next to each other. Possibly these things were not handled that strictly during war time and production plans were adopted quickly according to the availability of certain materials.

  6. This issue has been litigated over the past 20-odd years, and was finally resolved by the recovery of the Lake Michigan airplane.

    Areas such as the gear wells had zinc chromate painted over the salmon primer. Other areas such as the engine and accessory compartment were painted with YELLOW-GREEN zinc chromate then with light grey.

    No one has ever been able to verify wheel wells left in Salmon.

    The cockpit was painted overall Dull Dark Green, including the “hell hole”.

    The Salmon appears to be a primer that could be applied over different metal surfaces, allowing further paint to be applied without causing reactive problems with the underlying metal.

    You might wish to check my reviews here of building the Tamiya Corsair.

  7. Actually, the Salmon was used throughout Corsair production, as a primer to protect different metals and paints from reacting. I have personally seen a stripped F4U-7 and F4U-4 (helped strip both) that had that color on them under the zinc chromate. It was a much-thinned paint in comparison with that on the F4U-1, which may have been the result of finding out they didn’t need such a thick coat for the metallic protection.

  8. Many thanks, Tom. None of my questions have remained unanswered.
    But I have another one: was it possible to see shining through any of the primers at the F4U-x you helped stripping by some kind of wear or weathering? If yes, which one?

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