Zinc chromate yellow vs zinc chromate green

[Django]

What are the differences? Why was one color used over the other?

Or is one color more historically accurate for WWII (green I assume?)

[Dan K]

Differences: One's yellow and the other's green.

Historical accuracy: Both. Use was oftentimes dictated by supply and demand. In most cases it was the manufacturer's preference to use one color over the other.

[Tim Landers]

Here is an article that explains the differences. http://www.ipmsstockholm.org/magazine/2 ... urs_us.htm

Tim Landers

[Randune]

The B17 radio operators hatch I have is factory green. All other parts I've ever had were zinc green on the insides as well.



Randy

[Paul Krumrei]

isnt it easier to see leaks in certain areas when that area containing say, oil or hydralics had the metal painted the brighter yellow/green color?

[Eric Friedebach]

Here is a thread from last winter with some more pictures.

Yellow and green zinc chromate was created so it was easier to apply two or more coats - you just alternated the colors. Yellow was usually applied first, then green. If the piece only needed one coat then likely whatever was handiest was used. Apart from the colors they were identical.

[snj-5]

What everyone else said, with the addition that I understand
(at least in North American's case, probably the other US manufacturer's
as well), they used whatever color they had on hand at the time the
details were being fabricated / painted. Both colors were allowable
per the spec(s). Had a bunch of yellow ZC on hand? That was sprayed.
Bunch of green? Have at it.

Tends to drive restorers nuts when they have documented "survivor"
examples to go from only to find another documented / survivor
airframe that differed here and there. Bottom line, there was a war
going on and nobody was particularly concerned with having the
detail components of the airplane(s) all one color <grins>.

To draw an analogy, in the car restoration circles (I'm particularly
familiar with Corvettes), folks argue long and hard about what
the factory did 30, 40 or more years ago. The quick answer is
they did whatever they had to that day to get the cars out of
the plant and on the way to the dealers to be sold....

I've purchased and installed numerous "NOS" parts on my SNJ
from well known parts suppliers. Some had the lightest coat
of green ZC on them you've ever seen. Some had primer
applied so heavily that stripping the part of paint halved the
weight of it. Some were sprayed with yellow ZC (some heavy,
some light).

There's a picture in some recently published book of a (relatively)
young man spray painting (priming?) Bell P-39 cockpit door assemblies.
He has a funny look on his face, and is wearing no protection
what-so-ever (no respirator). Perhaps that points us towards a
possible answer as to why and how WW-II aircraft detail parts
were originally primed/painted the way they were. Everyone
involved was high on toxic paint fumes!

[Jiggersfromsphilly]

I have heard that the a/c that were involved with opps over water (USN) had several coats of Zink Chromate applied for preventive purposes vs the USAF land based ones.

[Django]

Thanks guys!

I'll try a test panel with yellow under the green.

[bdk]

I have heard that the a/c that were involved with opps over water (USN) had several coats of Zink Chromate applied for preventive purposes vs the USAF land based ones.

Some of the Navy aircraft had anodized skins I believe also. Some later USAF aircraft had no coatings at all internally (bare metal).

[RMAllnutt]

quote]Some of the Navy aircraft had anodized skins I believe also. Some later USAF aircraft had no coatings at all internally (bare metal).

As far as I know, skins weren't "annodized", but they were treated with alodine solution. It would not have been practical to annodize the skins. However, most forgings and extrusions on naval aircraft were annodized.

Cheers,
Richard

[Eric Friedebach]

I have some Stearman gear leg fairings that are anodized.

EDIT: Dan’s post below is correct. Dunno how I forgot all the other parts, including the aluminum pieces of the wing hardware.

I’ve spent enough time stripping paint off them…

Last edited by Eric Friedebach on Sat Sep 23, 2006 12:08 am, edited 1 time in total.

[warbirdfinder]

The final model of the Stearman, N2S-5/PT-13D, had all of its aluminum cowlings, fittings, struts, etc, anodized as the items were not painted.

As far as I know, skins weren't "annodized", but they were treated with alodine solution. It would not have been practical to annodize the skins. However, most forgings and extrusions on naval aircraft were annodized.

Depends on the airplane and the manfacturer. Virtually every piece of aluminum on a PT-17 Stearman was anodized, for example. Every channel, strut, and cowl. I'm rebuilding an old duster Stearman right now that used to be a Navy N2S and alot of the original paintwork was still intact on the fuselage frame (underneath a dozen or so other coats of paint). The order of painting seemed to be yellow zinc chromate, green zinc chromate, then a silver lacquer, and then we were into the postwar, civilian applied paint (the first color being a particularly hideous shade of green). Underneath all of that paint however, the metal was in great shape.

Also (skipping ahead a couple of generations) the Chinese Nanchang CJ-6A Dragon is completely anodized, and apart from the control surfaces is an all metal aeroplane.