Color is necessarily a subjective phenomenon, no matter what the many self-appointed experts say. It depends on the instrument that records the color (photographic film, photocell array, or human retina) and on the conditions under which it was recorded. When someone tells you that a given color matched a given paint chip (or CMYK value, RGB value, etc.), ask them what edition and printing of the chip matched, what manufacturer's paint was used, and how it was applied. Then ask, "When did it match that color? In what season? At what time of day? Under what weather conditions? at what altitude? At what latitude?" If a source cannot answer all these and more, it cannot give you a definitive answer.

For example, what color is the F-104? Aluminum? What color is that? Are you sure? As the three examples below show, an aircraft with the same finish can present a radically different appearance when the atmospheric and environmental conditions vary even slightly. Example 1 is what we usually picture when we think of a USAF Starfighter. The image looks like it was shot in reasonably diffuse light, at mid-morning or mid-afternoon (judging from shadows in the original), on a hazy or slightly overcast day. It exhibits the range of greys that we think of when we think "natural metal." But look at Example 2. Here, the light comes from almost directly above and the sky is very clear (as in the desert and/or at higher altitude). Vertical, noon-time light does not pass through much airborne dust, so it tends to be much bluer than we usually realize. The F-104 thus becomes a deep, metallic, hotrod blue. Example 3 was clearly shot early or late in the day, when the light comes from low in the sky and takes on a reddish-yellowish hue. Which is the correct color for a model or illustration of the F-104?

Example 1	Example 2	Example 3

The answer is, of course, "any of them." While bare metal is obviously an extreme case, it illustrates effects of light, time of day, weather, and location that affect every color we see, including the colors of the chips in the US Federal Standard, the Methuen Handbook, and the myriad, supposedly authoritative sources aimed at the hobbyist. Color standards can supply us with an approved color chip. But the appearance of a chip bears no precise relation to the mix of carriers, solvents, and pigments that will make an acceptable rendering of the intended color at full scale under given lighting conditions. To create a paint match, we have to compare the chip to similarly sized samples of the dry paint, a process that depends on conditions prevailing during the comparison.

Now, admittedly, not every color can give the appearance of an F-104 at noon. The materials used to finish an aircraft set limits to ways the finish can appear under a particular set of conditions. Manufacturer's paint recipes and government application instructions can thus give us valuable hints. But specifications do not prove that a vendor followed the recipe exactly, and nothing can tell us that a given finish was correctly applied at a particular aircraft factory or in the field. Wartime shortages sometimes force substitutions that can change the final appearance of the finish substantially. For instance, substituting linseed-oil varnish for the nitrocellulose-based carrier specified for many older aircraft finishes could make identical pigments look radically different. When pigments were supplied dry for mixing with a locally available carrier (as in the case of the WW1 British color PC 10 or Luftwaffe winter camouflage materials), such substitutions were common. In extremis, ground crews might substitute water, diesel oil, or in the dead of a Russian winter even gasoline. Surviving samples of unrestored aircraft fabric or painted metal structures can show us how a particular finishing system looks now, but, given the uncertain effects of time and storage conditions, can only give us hints of how the same system looked originally.

Many hobbyists view contemporary photographs as definitive authorities in matters of color. But, as anyone who has spent an hour in a darkroom with a professional can tell you, photographs do lie or, at least mislead. To start with, the colors in a photograph are at least as much a reflection of the film and development chemistry used as they are of the original hues and tones (to cite a well-known example, Kodachromes are warmer in color than Ektachromes, and neither records exactly what the average eye if there is such a thing sees). The color sensitivity of any given type of photographic material (whether color or black-and-white) varies further with age, temperature, exposure, and atmospheric conditions. Some chemistries produce images that are unstable over time, so that color shifts subtly (and not so subtly) with the passing years. Color information is also affected by the decisions the photographer makes when exposing and developing the film, such as filters used, exposure chosen, and development time.

So color judgments are just that: judgments. Whether you are an illustrator preparing art for a webzine, a modeller, or a government contractor trying to match 500,000 gallons of paint to an FS595 paint chip, you have to decide for yourself what constitutes a good color match under prevailing conditions and for a given application. Use the charts below as a guide, not as a gospel. Caveat pictor! ("Let the painter beware!")