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When planes come off the assembly line at the factory, they're green:

So why are most painted white? Surely a darker colour would hide dirt better?

Is there a reason planes are traditionally white?


Here's a clip that shows a Boeing 747 being painted:

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google.com/search?q=colorful+planes&tbm=isch - plenty of planes are not white at all. –  oakad Mar 17 at 3:57
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@oakad This is the reason for the word "generally" in the title :) –  Danny Beckett Mar 17 at 3:58
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It's not a primary reason, but hiding dirt is NOT what you want. 1. It increases drag. 2. It often indicates problems - leaking seals, internal pipe leaks, corrosion in exposed flap tracks etc. –  Simon Mar 17 at 19:49
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Ok, I do not find references to underpin that statement, but a gifted car mechanic once told me, that white lacquer is harder than other colors. (Well, most craftsmen in Germany have white cars...). –  TRNCFRMCN Mar 17 at 20:24
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The Concorde was painted with a special type of white paint because any other color would cause the airframe to heat up way beyond its design limits at Mach 2 cruise. The Pepsi Concorde was painted blue, and was hence not allowed to fly at Mach 2 for more than 20 minutes at a time: concordesst.com/history/events/pictures/pepsi6.jpg –  shortstheory Mar 19 at 10:53

14 Answers 14

up vote 49 down vote accepted

White has some significant thermal advantages over color. In most cases, this is probably just a benefit in terms of keeping the cabin slightly cooler. In the case of 'plastic' airplanes (those built with composite construction), some airframes require the use of white paint on upper surfaces to keep some elements within limits. Early Diamond Aircraft designs had a 38° C outside air temperature limit, past which the main spar is not considered structurally sound.

As a result, Diamond would only manufacture aircraft with predominantly white upper surfaces, as darker surfaces could result in significant heat gain.

DA-20 55C overtemp indicator

Avweb has an article on the DA-20 that shows the bright red over-temp indicator that raises the maximum temperature to 55° C, added as a Service Bulletin.

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I read some time ago that supersonic aircraft like Concorde also required almost all-white livery due to thermal issues –  orique Mar 18 at 7:13
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It's worth noting that I doubt this is the definitive answer, even though it's been accepted. The structural temperature issues are only really relevant for the newest composite designs. There's no place on earth that's likely to be hot enough to cause issues with an aluminum airframe. –  egid Mar 18 at 23:43
    
...except maybe a volcano. –  egid Mar 20 at 16:29
    
@egid: How about at 80,000 feet and Mach 3.2? The SR-71 Blackbird was built out of titanium because the high temp "enjoyed" at cruise speed would melt aluminum easily. –  Skip Miller Aug 14 at 13:42
    
Also, the SR-71 was black. It was heated by friction with the atmosphere, not by solar heating. Diamonds as noted above are white to avoid getting solar heat, the SR-71 was black to efficiently radiate the heat of friction away. –  Skip Miller Aug 14 at 13:51

The green coating is a primer (historically zinc chromate, these days zinc phosphate is used as it's less of an environmental hazard) - While you could theoretically fly around like that it is a rather ugly shade of green, so most folks (and airlines) tend to paint their aircraft some other color.

So why white?
White has a few advantages, but the two biggest ones I can think of are these:

  • White is a nice, neutral base color.
    Artists typically start out with a white canvas, or white paper - it's a color associated with "blank" and "clean" (the latter moreso if you actually wash the aircraft, of course...). Starting with a white base coat allows the airline's marketing department to paint whatever livery they want on their flying billboards.

  • White doesn't fade.
    Or perhaps it's more accurate to say "you don't really notice when white fades.". An average airliner will have several paint jobs during its service life, but the longer you can go between having to reprint the plane the better, and if you don't have to worry about the paint fading and looking old for a good long while you cans stretch the time between paint jobs without having your passengers start making snide comments about your fleet of flying hoopties.
    All colored paints will eventually fade from exposure to sun and the elements, particularly exposure to the sun at 30,000 feet, where substantially more UV radiation is hitting the paint and accelerating the fading process.


Of course there's nothing that says the base coat HAS to be white: Southwest has a very attractive blue/red/orange livery, and American Airlines has traditionally incorporated polished aluminum in their livery (which also affords a substantial weight savings, by not priming & painting the entire body of the aircraft).

Current Southwest livery American Airlines old livery (MD-80)

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You say "a substantial weight savings" - Do you have a reference for how much the paint weighs for a given plane? –  Richard Miskin Mar 17 at 6:08
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@RichardMiskin It obviously varies depending on how much surface needs to be covered, and to a lesser extent on the type of paint used (urethane paints are pretty much the standard in aviation these days). This Daily Apple article has a table from Boeing, which puts the weight of a full paint scheme on a 747 at 555lbs (versus 55lbs for polished skin & a logo). –  voretaq7 Mar 17 at 6:25
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@vortaq7 There was an article in the seat pocket magazine years ago on an American Airlines flight. Their former livery - polished aluminum accented by a stripe of multicolored paint - saved 200 pounds. that is from memory and applies to the MD-80 series. So they save the weight of one passenger on each flight. I wish I could remember the fuel savings they claimed, but it was substantial on an annual basis. –  Skip Miller Mar 17 at 13:09
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"Ugly shade of green"... you do realize it's St Patricks Day, and you've just antagonized everyone of Irish descent? ;) I seem to remember a story about interned B-29s that landed in Russia during WWII due to battle damage over Japan, and the Russians copied them exactly, down to the exposed green primer in the aft portion (the factory had run out of interior white paint, or something). –  Phil Perry Mar 17 at 18:48
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@RichardMiskin Check out this YouTube clip from Megafactories, with Boeing painting a new 747. This would concur with voretaq7. –  Danny Beckett Mar 17 at 23:52

Of course, in certain situations a plane has to be painted white...or another colour.

Concorde had to be finished in a special, highly reflective white paint to mitigate the extreme heating effects that friction caused at mach 2.

[It] reaches 127° C at the nose and trailing edge, but the special ‘high-reflectivity’ white paint helps reflect and radiate heat. Its reflectivity is 80 out of 100, compared to the rating of normal white paint of 45-50 out of 100, Concorde is re-painted every three years.

Conversely, the SR-71 Blackbird was painted matte black for almost exactly the same reason, plus some radar signature reduction.

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That Concorde-link gives a 403. :-( –  Martin Schröder Mar 18 at 20:59
    
@MartinSchröder It seems to be working now, but you can always view it at web.archive.org/web/20130713084122/http://… –  Danny Beckett Mar 20 at 22:03
    
Reflective paint makes the plane a poor radiator of heat. –  David Richerby Mar 31 at 0:15

Two reasons for white I've been told many times are:

  • white paint is cheaper than other colours (either because it costs less and/or weighs less)
  • white makes it easier to apply names and logos of other companies when leasing your aircraft to someone else. Saves a trip to the paint shop, instead you just apply stickers.

Both make sense, but whether they're the main reason I don't know.

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Do they really use stickers for names and logos? I would think it likely they would come off too easily. –  Phil Perry Mar 17 at 18:54
    
@PhilPerry yes, they do. And yes, they do sometimes come off when not properly applied. But it's quite possible to use stickers that require special chemicals to get off. –  jwenting Mar 18 at 7:43
    
Why couldn't you place a sticker on an airplane with some other color? –  Speldosa Apr 1 at 14:01
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@Speldosa you can. White is however nicely neutral. If you put KLM stickers on a US Airways aircraft... Now put them on an Air France aircraft... In both cases after removing the original titles and logos of course. And that's how rental/short term lease companies work. –  jwenting Apr 2 at 7:03

White makes it easier to spot another plane in the air, since white shows up well against the ground. This is why many early planes were colored on the bottom half and white/silver for the rest.

Of course, this matters much less with modern IFR equipment and doesn't matter really at all with high-altitude jets, but old habits die hard, I guess.

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is this also the reason why military planes are not white? –  user13107 Mar 17 at 7:01
    
@user13107 That's probably more to do with stealth/camo: Dark spot under cockpit on A-10s –  Danny Beckett Mar 17 at 7:39
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I'm not so sure about white being easy to spot - at least in my personal experience. The most visible plane I've ever seen was painted an utterly hideous shade of yellow-green (about the same color they paint the ARFF trucks) - I saw that thing buzzing away in the pattern when I was about 8 miles from the airport and never lost sight of it! –  voretaq7 Mar 17 at 16:09
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@user13107 White is actually pretty hard to spot when looking up at it, particularly if there are clouds. This is why some airplanes have white tops (easier to spot with the ground as a backdrop) and dark colored bottoms which stand out from the sky. –  Lnafziger Mar 17 at 18:39
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And consider that a lot of birds and especially fish do it the other way around, lighter underneath ;-) –  Steve Jessop Mar 17 at 19:24

I work for a printing company.

Think of this - why everything is printed mostly in black ink? why not navy blue, or dark hunter green?

Because black is a stock color.

The manufacturer stocks it, and uses it left and right. Most other colors have to be a special order - this comes with increased costs, lead times and paint expiration. If you did not use all of it, paint does expire.

To the printer-happy community let me remind you that painting a jet is not like printing a page where three base inks are used to create a perception of color. Paint of any color has to be manufactured separately.

So I think that from a manufacturing standpoint it is just so much cheaper to use stock white paint.

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Apart from technical reasons, I am not really aware of, let me put it this way: Would you fly in a black plane? Probably not.

You associate colours with objects, feelings, situations etc.

White can be trivially associated with sky, just like blue. I believe most airlines stick to these colours, since it helps associating the brand with sky. But the colours can have deeper meaning which is often used for marketing purposes. White is often associated with trust and perfection. Blue is associated with quality, security, trust or business. Notice many company logos are blue and white - Facebook, IBM, GE, Samsung, Hilton.

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Actually this black plane looks pretty slick: i.stack.imgur.com/5oUfl.jpg –  Danny Beckett Mar 17 at 23:36
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I must say this really surprises me and I was not aware of that. –  Petr Mar 17 at 23:46
    
To be fair, this has special meaning in New Zealand. Their national rugby team is named the All-Blacks, and Air New Zealand as a part of their sponsorship of the team has adopted the black livery for a few of their planes. –  Xander Mar 19 at 0:02
    
Though personally, I'm quite a big fan of this black plane: upload.wikimedia.org/wikipedia/commons/4/47/… –  Xander Mar 19 at 0:04
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The reasons for the colors to be used is just my opinion, however the color associations are not made by myself, you can see for instance joehallock.com/edu/COM498/associations.html. I just corrected few inaccuracies. –  Petr Mar 19 at 1:47

Most of the above reasons are valid. I worked at Eastern airlines and we switched from the white/blue livery to polished aluminum because the weight/drag reduction vs. increased manpower cost still was overall cost effective. Remember a 747 uses around 90 gallons of paint weighing in the vicinity of 550 pounds.

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Another minor reason is that white color protects from adverse radiation better.

In regards to nuclear bombers this is called 'anti flash white', though regular planes flying at high altitudes supposedly benefit from this as well.

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(Please note that am not at all familiar with civil nor military aviation, I'm only putting it here from memory.) –  mafu Mar 30 at 15:13
    
Interesting reference. Sounds like an extreme example of reflecting heat well. –  fooot Mar 30 at 16:57

Your all right to a point / close:

Here are the main factors in order of importance:

a. White paint is both cheap and easy to apply.

b. White paint on most of the aircraft allows for quick and easy resale (the new airline simply puts new tail art on it)

c. White paint shows any anomalies quickly - hydraulic/fuel leaks, dirt, damage.

d. White paint has the best thermal reflective properties for both radiation from the sun - and reflected radiation from the tarmac (although in northern climates / winter this is reversed)!

People don't generally choose their airline because of it livery - they generally choose the cheapest fair. therefor white paint is the colour of choice - It all boils down to money folks…. :)

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could you substantiate your claims? what makes white paint cheap/easier to apply (!) than a color paint? Also, please consider polishing language and spelling. –  Federico Aug 14 at 13:16

It's quite simple actually: White paint is both cheaper and lighter than paint with colorant added to it. Both of these are important when trying to reduce cost at an airline!

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I'm led to believe cost isn't the only reason... Something about white reflecting heat? airliners.net answers.yahoo.com –  Danny Beckett Mar 17 at 3:25
    
I'm not sure what the weight differential is - when I go in for my paint job I'll have to pick some brains on that. I imagine the difference isn't too substantial, but on the scale of an airliner an ounce or two per gallon would add up to quite a bit of weight :-) –  voretaq7 Mar 17 at 3:29
    
@DannyBeckett, Surfaces that appear white appear so because they reflect all wavelengths of light. Surfaces that appear black appear so because they absorb all wavelengths of light. Other colors are in between. When a material absorbs light energy, it gets transferred into heat energy. I'm not sure that this is the primary reason it's commonly used on aircraft, but I'm sure it does help. –  reirab Mar 17 at 16:53
    
Are you sure white is lighter? Coloured paint is not white paint with a colour added: white paint is typically itself coloured with titanium dioxide. –  David Richerby Mar 19 at 1:34

White paint won't absorb as much heat as black or another color, imagine walking on bare blacktop vs. the white painted line. I found this article to save me the explanation. The black paint absorbs the entire spectrum of photons, whereas the white reflects most of the photons. When a photon is absorbed, its energy is absorbed (a photon is energy) and the heat of the plane increases.

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As stated before, White is cheaper. There is no thermal benefit for subsonic planes at cruising altitudes. Windchill and ambient temperature at flight levels are below freezing.

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I think a white has some significant thermal advantages over color also another colour will be mixture of two or more colours as orange red+yellow that mean more weight more costs .

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the idea that the mix of two colours is heavier is quite a stretch. Any data to support it? –  Federico Aug 28 at 8:39
    
It's indeed wrong. Using red,yellow,cyan,black makes sense for painters and printers which need to produce any possible color by mixing. And those paints are far from pure; they already mix a bunch of pigments to get the right shade. But if you produce paint in larger batches, you're not going to produce that by mixing what are already mixes of pigments. You'll create a custom mix of the raw pigments. (Which may very well contain titanium dioxide to make the paint brighter) –  MSalters Aug 29 at 16:25

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