How the price of paint is set in the hearts of dying stars
January 26, 2015 7:18 PM   Subscribe

The Smithsonian Magazine reminds us that "Barns are painted red because of the physics of dying stars", summing up a more detailed post by Google employee Yonatan Zunger on the nature of stars, the atmosphere, and cheap paint found on barns.
posted by mathowie (60 comments total) 25 users marked this as a favorite
 
That's pretty cool. I never thought much about where all the iron came from. I guess that means my very rusty well water is liquified stars. Cheers!
posted by Thorzdad at 7:27 PM on January 26, 2015 [2 favorites]


Well it also determines what the core of our planet is made of. Other factors could have easily prevailed in the matter of barn paint.
posted by localroger at 7:28 PM on January 26, 2015


My barn and I approve of this post. Now I can tell my daughter that it is secretly covered in stars!
posted by MonkeyToes at 7:29 PM on January 26, 2015 [3 favorites]


How much cheaper was the red paint vs. other colors MonkeyToes?
posted by mathowie at 7:31 PM on January 26, 2015


How much cheaper was the red paint vs. other colors MonkeyToes?

I'm not sure I can say, but that's partially because of the strange requirements of barn painting. A house painter, I could probably find. But the barn paint crew finds us. Every few years, a pickup truck rolls into the driveway, and the dog goes nuts, and tiny little fast-drawling Tommy hops out and in his Carolina quick-mumble, says "Ma'am, you're lookin' as lovely as evah, but your barn, your barn, now, well we may not be able to get back here for another few years, an' I got my crew here this week, and I'll just write you up a quote." And we haggle, and he promises to take me out dancing if I agree to let them paint the barn, and two days later, my barn is painted. His crew brings the paint -- I think they buy as they go, but I'd have to run out and check the label on the big can he left behind. That means they are looking for a paint that's widely available, and lower-cost to them, and red is all that they've ever offered as a barn color.

The doors in the picture, though, were added between visits (old ones were dangerously rotted) and I went the Sherwin-Williams best outdoor paint so I don't have to do this again for many years. I chose that shade to go with the barn as it had been painted. Eggplant purple or tangerine would not have been any more expensive, but I think the salesman might have refused to sell me another color, considering it a crime against barns.
posted by MonkeyToes at 7:44 PM on January 26, 2015 [26 favorites]


Oh cool. I was just looking at Google Shopping and it's tough to find the exact same paint for barns in red and white, but it looks like maybe white costs about 20% more ($78 for 5 gallons of red vs. $97 for white) but I also wonder if it's just social convention at this point since red barns look "right" to me and I couldn't imagine anyone painting theirs another color.
posted by mathowie at 7:47 PM on January 26, 2015 [2 favorites]


Lovely barn, MonkeyToes, but do you ever go dancing?
posted by BlueHorse at 7:57 PM on January 26, 2015 [4 favorites]


but do you ever go dancing?

No! Last time he rolled in I greeted him with a smile and "TOMMY FULL NAME, you promised to take me out dancing and never did! You broke my heart, you awful man!" just so we could get negotiations off on the right foot.
posted by MonkeyToes at 8:02 PM on January 26, 2015 [39 favorites]


I recall a comment, might even have been on metafilter, where someone talked about how their family repainted the barns. They'd drive up to the Iron Range, find a couple of nice boulders of iron oxide ore, bring them back home and put them in a grinder, and then mix with milk and a few other things to make paint. I suspect the extreme cheapness of red paint and the tradition of it being used on barns dates to such homemade paints such as that, not modern day paint pricing.
posted by tavella at 8:06 PM on January 26, 2015 [3 favorites]


The second more detailed post breaks the combo of nucleons out as, "And what has 56 nucleons in it and is stable? A mixture of 26 protons and 30 neutrons -- that is, iron."

OK, so if I know the atom has 56 nucleons in it, how I supposed to know that it's the above ratio? This is why I was glad my major only required two semesters (one year) of chem classes. The number of neutrons always seemed to have no rational basis, at least that I could discern.
posted by InsertNiftyNameHere at 8:06 PM on January 26, 2015


"...and I couldn't imagine anyone painting theirs another color."

O rly?
posted by joseph conrad is fully awesome at 8:07 PM on January 26, 2015 [1 favorite]


This is your monthly reminder that having super-smart people, nearly infinite resources and a very good product are still not sufficient to win in a competitive marketplace.

Also, barns.
posted by GuyZero at 8:18 PM on January 26, 2015 [3 favorites]


Quilt barns. One day....
posted by MonkeyToes at 8:18 PM on January 26, 2015 [3 favorites]


At farmpaint.com we get 55 gallon drums for (approximate, I'm on a phone):
- black $270
- grey $415
- red $415
-brown $430
- green $495
- white $700

You can doubtless stretch a bit cheaper, but if you assume that the pigment in black is maybe $20 of the cost (basically free - waste carbon is not hard to find), then the binder is $250 and ocre is $165, while titanium dioxide (white) is $450ish. I'll bet the difference is a bit bigger in fact because black is a better pigment than white.
posted by wotsac at 8:20 PM on January 26, 2015 [3 favorites]


O rly?

green barns!
posted by BlueHorse at 8:24 PM on January 26, 2015 [1 favorite]


Skim milk, lime, and red.clay mix, coated with linseed oil, made from flax. It is a paint they made.
posted by Oyéah at 8:29 PM on January 26, 2015 [1 favorite]


Green barns, red barns, what's the difference?
posted by spaceman_spiff at 8:31 PM on January 26, 2015 [2 favorites]


I like those yellow barns but I think the one I'm most used to passing near home are boring brown. But they're also falling down, so they may have been red once.
posted by maryr at 8:59 PM on January 26, 2015


O rly?

Pamela Barnes

I love the color blue, but those blue barns just look wrong. There's just something about a warm red barn that looks so nice. (Although this cobalt blue one looks nice--it has the warmth that those lighter blues lack.
posted by blueberry at 9:04 PM on January 26, 2015 [2 favorites]


I heard this on the radio once, and the scientist had an interesting way of looking at it. He said that the commonality of iron explains not only why our barns are red, but that the barns of any alien civilizations we encounter are likely to be red too.
posted by eye of newt at 9:07 PM on January 26, 2015 [14 favorites]


barns of any alien civilizations we encounter are likely to be red too.

That assumes that cheapness is the primary virtue.

There are lots of other food or livestock storage structures that aren't red usually because they don't get painted at all. I mean, why do we even paint barns? Because a) they're made of wood, which is the cheapest construction material available in northern europe and north america and b) because untreated wood tends to rot and needs to be protected from rain by having its surface sealed.

Maybe aliens will have stone barns. Or they'll have a lot more rot-resistant trees like cedar or redwood. Etc.
posted by GuyZero at 9:38 PM on January 26, 2015


Apropos of nothing: what is the significance of specifying "Google employee" in the FPP description? To explain why it's on G+?
posted by We had a deal, Kyle at 9:38 PM on January 26, 2015 [4 favorites]


InsertNiftyNameHere: OK, so if I know the atom has 56 nucleons in it, how I supposed to know that it's the above ratio? This is why I was glad my major only required two semesters (one year) of chem classes. The number of neutrons always seemed to have no rational basis, at least that I could discern.

It's not my area but I've heard some things: if you took introductory chemistry you probably learned about orbitals, right? How their neat blobby shapes and sizes come from the quantum wave nature of how electrons orbit the nucleus, and you can use that to calculate all the possible energy levels of the electrons?

Ok so nucleons have orbitals too. And for any combination of protons and neutrons you can calculate all the energy levels the nucleus can have. And if there's a way for a nucleus to reach a lower-energy state by some decay it will. Those are the calculations that predict the lowest-energy nucleus with 56 nucleons has the 26/30 combination.

I couldn't tell you how to actually do them, though, they're mad complicated. That's because the nuclear forces themselves are more complicated. Also it's good to remember the nuclear orbitals, like electron orbitals, are just approximations and reality is even weirder and harder to calculate. Intuitively I think I'm remembering these rules of thumb right:

All nucleons attract each other through the strong force. They also repel just the same type through Pauli exclusion. Together those two rules tend to make a 50:50 mix the most stable, because any other ratio would increase the Pauli repulsion without changing the strong attraction. But protons also have a repulsion from their electric charges, so as that number grows the most-stable ratio shifts toward having more neutrons. Lastly both nucleons like to pair up with their own type (just like electrons do, if you remember) so nuclei that have even numbers of one or both will tend to be more stable.
posted by traveler_ at 10:04 PM on January 26, 2015 [1 favorite]


We had a deal, Kyle: "Apropos of nothing: what is the significance of specifying "Google employee" in the FPP description? To explain why it's on G+?"

That seems redundant. Only Google employees ever use G+.
posted by Joakim Ziegler at 10:11 PM on January 26, 2015 [2 favorites]


....or pink.
posted by pjern at 10:12 PM on January 26, 2015 [2 favorites]


That is so interesting and showed me a new way of looking at things. Thank you!
posted by Lynsey at 10:14 PM on January 26, 2015


We live on a big chunk of silicon and iron. It's not surprising that iron lasts a long time, because if it didn't, it would be gone after 4 billion years.

The reason barns are painted with an a paint based on Fe2O3 isn't that we have lots of it. It's that we have lots of it and it forms a long lasting paint. There are lots of compounds we have that don't last. We don't use them in outside paint.

For those wondering about blue barns, look at copper, for those wondering about white barns, look at titanium or lead.

Amazing what oxidation will do for you. See how old Volvos look like old blue Barns.
posted by eriko at 10:28 PM on January 26, 2015 [1 favorite]


We had a deal, Kyle: Yonatan often posts publicly about his work, and when he does, it's just shy of being an official statement from Google, because he was the lead engineer in charge of developing Google+. He also posts a ton of cool stuff that's not related to his work, but his job is definitely a major part of his online persona, so IMHO it's a reasonable way to introduce him.
posted by shponglespore at 10:40 PM on January 26, 2015 [3 favorites]


what is the significance of specifying "Google employee" in the FPP description?

I only mentioned it as opposed to say, an actual astronomer or physicist or something. It was a great story, and I was wondering if the scientists on MeFi could back it up or instead find fault with it. The hypothesis about cheap iron equaling red color sounds legit though.
posted by mathowie at 10:45 PM on January 26, 2015 [4 favorites]


OK, so if I know the atom has 56 nucleons in it, how I supposed to know that it's the above ratio?

You are me. You are studying for your physics graduate qual exam. You see this type of question in an old exam booklet. Since it hasn't showed up in recent years, you figure there's a low chance of it rearing its ugly head, so you don't bother studying that material. Guess what shows up on the exam?

Short answer is, I dunno.
posted by Standard Orange at 12:25 AM on January 27, 2015 [4 favorites]


What do you mean "barns"? All wooden houses should be painted in a proper red colour, unless you're some kind of bourgeois city snob who's just trying to show off.

(see also: Hell on earth, falukorv and little red cottages)
posted by effbot at 12:42 AM on January 27, 2015 [3 favorites]


the barns of any alien civilizations we encounter are likely to be red too

They're not even red in Europe, dude.
posted by Segundus at 1:37 AM on January 27, 2015


Just about exactly a year ago, I wrote a detailed comment describing the sequence of events preceding a supernova -- the main elements and nucleosynthesis involved, relative quantities, and time scales.
posted by Ivan Fyodorovich at 1:48 AM on January 27, 2015 [4 favorites]


Incidentally I rather doubt that the price of red paint has anything much to do with the price of iron. If red paint actually is cheaper, it's most likely because it gets produced in larger quantities: and it probably gets produced in larger quantities partly because you all paint your barns the same colour.

Which is a matter of inscrutable local culture, the same thing that presumably explains why you've got retro wooden barns that need constant repainting in the first place.
posted by Segundus at 1:57 AM on January 27, 2015 [1 favorite]


As far as I know, in car paint, red is one of the most expensive basic colors. But I suspect that's because the pigment is not iron-based, though I doubt it's cadmium-based these days.
posted by maxwelton at 2:12 AM on January 27, 2015


"Incidentally I rather doubt that the price of red paint has anything much to do with the price of iron."

It's not iron but iron oxides, which is an important difference with regard to the economics.
posted by Ivan Fyodorovich at 2:22 AM on January 27, 2015 [3 favorites]


White paint is expensive because of the titanium dioxide. The better the opacity, the more TiO2 it contains, which is why any white undercoat worth the trouble costs a fair bit more than the fancy-coloured paint that goes on top.
posted by pipeski at 2:59 AM on January 27, 2015


As far as I know, in car paint, red is one of the most expensive basic colors.

That's mostly licensing fees, right? :-)
posted by effbot at 3:25 AM on January 27, 2015


This is one of those James Burkian Connections types insights that are smart, interesting, slightly unobvious, offer a great answer to a question many people have asked themselves which is almost certainly completely wrong, isn't it? All the answers in this chain of reasoning might be correct, but the conclusion may still be false.
posted by MartinWisse at 4:35 AM on January 27, 2015 [6 favorites]


They're not even red in Europe, dude.

Yes, but, socialism!!!!
posted by Thorzdad at 4:44 AM on January 27, 2015


OK, so if I know the atom has 56 nucleons in it, how I supposed to know that it's the above ratio?

You don't. It's kind of weird to think about elements having N nucleons and then deciding their apportionment between protons and neutrons, since that's kind of orthogonal to the way that nuclei are built up. The original author is talking in numbers of nucleons because he's thinking about the curve of binding energy vs nucleon number rather than the actual nucleosynthetic process (silicon burning in the case of iron). In general though the issue of proton vs neutron number is wrapped up in the so-called "valley of beta-stability", which I'm hoping is googleable because I would get it all wrong if I tried to write it out.
posted by kiltedtaco at 6:31 AM on January 27, 2015 [1 favorite]


I should add that nucleosynthesis is an incredibly fascinating subject that has way more depth to it than just stars make iron, supernovae make heavy elements, and that while we've had the basic ideas figured out for the past 60 years there is still tons we don't know about the subject. This is partially because to do nucleosynthesis right you have to do supernovae right (and we can't), and you need to do nuclear physics right (which we can often only constrain with the results of nucleosynthesis), and the only observations we have are of stars, but to understand those you really need to know the history of galactic chemical evolution (which we definitely do not know, and which depends on the nucleosynthetic yields). It's a really crazy challenge that doesn't get as much popular press as I think it deserves.
posted by kiltedtaco at 6:43 AM on January 27, 2015 [2 favorites]


I knew there had been discussion of red barns here -- from the man of twists and turns, this previously: "the all-time most popular FAQ at The Barn Journal."
posted by MonkeyToes at 6:44 AM on January 27, 2015 [1 favorite]


"So, to sum up: many barns are painted red because paint protects the wood against weathering; because the pigment that went into red (or, more accurately, “Spanish Brown”) paint was the cheapest available two centuries ago, due to the abundance of iron oxide in the soil (due to nuclear physics and blue-green algae) and its ease of preparation for use; and because, despite the fact that green is as cheap as red today, humans tend to display a preference for the familiar."
-Dead Star Barn, ediblegeography.com
posted by jammy at 6:47 AM on January 27, 2015 [3 favorites]


GuyZero: Maybe aliens will have stone barns. Or they'll have a lot more rot-resistant trees like cedar or redwood. Etc.
Cedar and redwood alien barns would still be quasi-red. However, that red is due to tannic acid, which is pretty much just H&O combinations, so... no iron. It's just ironic that you've picked reddish woods as an example of how to avoid using reddish paints.
posted by IAmBroom at 9:02 AM on January 27, 2015


eriko: It's not surprising that iron lasts a long time, because if it didn't, it would be gone after 4 billion years.
Gone where, exactly? Oxygen doesn't last a long time; it's highly reactive; it's still here. I think you're confusing chemical stability with ... I dunno what.

Iron oxide resists low-energy "attacks", like water ionic charges (dissolving), and medium-energy "attacks", like UV-light (sunlight bleaching), because it forms a non-ionic, highly stable compound.

Because oxygen is highly reactive, iron is usually found (on the surface) bound to it, in its lowest-energy compound: FeO2 (there are a few iron oxides; not all are red - such as traditional steel bluing, but most of the non-red ones aren't as stable).

Not coincidentally, silicon on the surface is often bound up as silicon dioxide, or quartz (common sand, and also in the exoskeletons of some ancient plant species) - but silicon dioxide is SO FREAKING STABLE because its lower energy transitions are all filled, so it's colorless. Colorless makes for a really bad pigment, of course, so while the paint would protect the wood from water, it would do nothing for UV attack.

Ergo, rust-colored paint.
posted by IAmBroom at 9:11 AM on January 27, 2015 [1 favorite]


kiltedtaco: The original author is talking in numbers of nucleons because he's thinking about the curve of binding energy vs nucleon number rather than the actual nucleosynthetic process (silicon burning in the case of iron).
This phrase bothered me A LOT, so I googled it. Turns out "silicon burning" is a nuclear fusion process unrelated to "burning" burning. TIL...
posted by IAmBroom at 9:17 AM on January 27, 2015


The fusing of light elements releases energy, and the fission of heavy elements releases energy. Iron and nickel are too heavy too undergo fusion but too light to undergo fission--either process would require more energy than would be released. So once a star runs out of lighter elements to fuse, it's stuck at a point of net energy loss. Fe and Ni are at the peak of the nuclear binding energy curve, with 56Fe being the third most tightly bound nuclei.
posted by dephlogisticated at 9:48 AM on January 27, 2015


They're not even red in Europe, dude.

He says, just after someone posted a link about how red barns and cottages are considered a national symbol in at least two European countries :-)

... despite the fact that green is as cheap as red today, humans tend to display a preference for the familiar.

Painting your barns green sounds like a lousy idea. Wouldn't that make them a lot harder to find?
posted by effbot at 9:57 AM on January 27, 2015 [1 favorite]


The dying star painted my barn red. Fine. We are supplied with enough to last us until time winds down and barns turn back into their constituent atoms.

But I know why firemen wear red suspenders.
posted by mule98J at 10:36 AM on January 27, 2015 [2 favorites]


Unfortunately for the person who wrote this whole involved story, red paint is not cheaper. Red and white barn paint cost the same.
posted by w0mbat at 10:59 AM on January 27, 2015


Pfft, that's Home Depot. I'll place my trust in prices from Farmpaint.com
posted by filthy light thief at 11:34 AM on January 27, 2015 [2 favorites]


Curiously, a barn is also a unit of measurement used to measure the cross-sectional area of nuclei.

COINCIDENCE?

(and, famously, a barn-megaparsec is a unit of volume roughly equivalent to 2/3rds of a teaspoon, and thus not very helpful when specifying enough paint for a farm barn. And an autobahn is a seminal song in the history of electronic music, which might help you enjoy the action of painting a barn, and a barn is a pretty good place to put on a party where you can play such music at an acceptably loud volume.Especially in Sweden, where you can enjoy Forest Star moonshine vodka in, say,five barn-megaparsec shots.)

James Burke, I've got your back.
posted by Devonian at 11:43 AM on January 27, 2015 [5 favorites]


This reminds me of
posted by rifflesby at 12:22 PM on January 27, 2015


The engineers who designed the SRBs might have preferred to make them a bit fatter, but the SRBs had to be shipped by train from the factory to the launch site.

This (the railroad loading gauge) shows up in so many odd places it's amazing.

The 737 comes immediately to mind, but it's fuselage width was derived from 707, and I can't tell if 707/KC-135 fuselages were designed to be shipped by rail. So that case is unclear.
posted by kiltedtaco at 12:55 PM on January 27, 2015


w0mbat: Unfortunately for the person who wrote this whole involved story, red paint is not cheaper. Red and white barn paint cost the same.
Yes, and they're both exactly the same price as gold, per troy ounce. If you agree to pay my prices.

However, if you pay for the cheapest paint available throughout the 19th and 20th centuries, there's quite a price differential.
posted by IAmBroom at 1:17 PM on January 27, 2015




This phrase bothered me A LOT, so I googled it. Turns out "silicon burning" is a nuclear fusion process unrelated to "burning" burning. TIL...

For more weird language, ask a stellar astronomer what a 'metal' is.
posted by vibratory manner of working at 3:30 PM on January 27, 2015 [2 favorites]


In fairness to astronomers the very next element past helium actually is a metal in normal usage, and in astronomical terms it's a useful contraction for "everything else." But yeah, oceans and atmospheres are mostly metal to astronomers. But I guess rocky planets are heavy metal.
posted by localroger at 5:31 PM on January 27, 2015


just after someone posted a link about how red barns and cottages are considered a national symbol in at least two European countries

Dammit, my one fatal weakness - overlooking Sweden! Count Wallenstein had similar problems.

Actually I wonder if Swedish batchelor farmers (as it were) could be the real ultimate reason for barns being red in the US?
posted by Segundus at 3:31 AM on January 28, 2015 [1 favorite]


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