Just for reference ad I hope to find the actual color codes to match, here are three examples of Zinc Chromate that are available
Regarding Aircraft color, but perhaps somewhat useful if debated: http://www.alliancecoatings.com/warbirds.php
Zinc Chromate Yellow
In US aircraft use in the 1930s to 1940s, the Zinc Chromate primer was frequently used in the raw mixture yellow tone. This is sometimes referred to as Zinc Chromate Yellow. Like stated above, there is no definitive color pattern as this may have varied between manufacturers and batches of these primers.
In the immediate pre-war and early war period, the raw yellow Zinc Chromate primer seems to have been dominating.
Zinc Chromate Greens
Sometimes, Zinc Chromate was mixed with Lamp Black paste to give a bit more UV resistance (Zinc Chromate is very sensitive to photolitic reactions) and more durability in high wear areas.
Mixing with black gave greener tones, which, depending on the amount of black added could run from apple greens to medium olive greens.
There were many variations in Zinc Chromate Green. Originally, manufacturers were expected to mix raw Zinc Chromate, black enamel and aluminum paste or powder. Several blacks and grays could substitute for the black enamel, and a shortage of aluminum powder/paste caused a reformulation without it in 1942.
Some aircraft manufacturers ordered pre-mixed Zinc Chromate Green (Curtiss Cockpit Green, ordered from Berry Brothers, being an example of this).
There is evidence that such variety of shades occurred in the manufacturing practice of US aircraft factories. Where sufficient color evidence is available, it is possible to find all three colors used on the same aircraft - for example, the yellowish raw color in the wheel wells, the apple green tones in the gun bays, and the darker green in the cockpit.
And as a note
: Recent studies have shown that not only is zinc chromate highly toxic, it is also a carcinogen. Exposure to zinc chromate can cause tissue ulceration and cancer. A study published in the British Journal of Industrial Medicine showed a significant correlation between the use of zinc chromate and lead chromate in factories and the number of cases in lung cancer experienced by the workers. Because of its toxicity the use of zinc chromate has greatly diminished in recent years.
That does not mean we can't mix a suitable looking color for realism