It’s black, it’s shiny, and it’s … covered in your fingerprints. Out of the box, a jet black Apple’s iPhone 7 is super shiny. The company achieved this blinding finish using a proprietary nine-step process that includes powder-tumbling and particle-bathing. Whatever they did, it’s gorgeous, and everyone wants one. The waiting period to get one already stretches into November.

Most of those people will admire their super shiny phone exactly once, because, as reviewers have noted, that lust-worthy luster turns into a serious smudgefest within minutes. Like, way worse than the not-jet-black black. Turns out, the same properties that make for superior sheen also attract fingerprints faster than a season of CSI: Miami.

The likelihood that you’ll leave a fingerprint behind on any given object depends upon two variables: sweats and surfaces. Fingerprints typically are comprised of two kinds of sweat. The first, eccrine sweat, comes out of pores on your fingertips and mostly water and dissolved salts. The sebaceous sweat you pick up by touching your head or face contains sebum, an oily mixture of fatty acids and waxes. Together, the two sweats create a film that coats the unique swirls and whorls of your epidermal ridges. That’s what you leave behind in a fingerprint.

How much of each sweat you have matters. If the sweat on your fingertips is mostly water, the droplets you leave on a smooth surface will spread out more. The more oils and waxes you have, the more viscous and tacky the droplets. The surface tension in those droplets is higher, creating a so-called high contact angle (imagine a tight ball of sweat versus a loose, flat drop–the tight ball makes closer to a right-hand angle with the surface). This contact angle determines how easily you can visualize a fingerprint. High contact angle equals low visibility. Low contact angle equals print city. “Whether or not you can detect a fingerprint is more about how that droplet moves on the surface at the point of contact, as opposed to how likely it is to evaporate over time,” said Dr. John. W. Bond, a forensic chemist who worked for the Northamptonshire Police for 20 years before becoming a lecturer at Leicester University in the UK.

Now, to the iPhone. Contact angle also is determined by the properties of the surface material. Something like smooth glass–or the super-shiny new iPhone–creates a low contact angle because there isn’t anything for the sweat droplets to push against except the glass itself. But say you take a metal surface like an an anodized aluminum iPhone and roughen it up ever so slightly. The result is a matte texture: That molecular-level coarsening scatters light as it hits the surface. But the unevenness on the surface also is enough to stop the droplet from wanting to spread out. So that slightly dull appearance of the silver, gold, rose gold and regular black iPhone 7s is caused by the thousands of macroscopic edges on their surfaces. And that’s why they do a better job repelling fingerprints.

But no sweat. If you’re dead-set on on owning a jet black iPhone, here’s a trick for keeping it squeaky clean. High humidity causes the salt in fingerprints to attract water and swell, while high temperatures cause the sebum deposits to liquify. Both make them easier to wipe off. You’ve got to really crank the heat though–up to 95 degrees F. So maybe it’s time to invest in that sauna you’ve always wanted. Or you could move to Mumbai. They’re probably getting 5G LTE soon, right?

17 Comments

  1. Kind of a moot point when 99% of people put their phone in a case as soon as they buy it.

  2. Apple hate. It’s everywhere.

  3. Scarlet_Billows

    MFG, this is just lame.

  4. You said it man. Phones, car interiors, appliances, with glossy ‘piano’ black finishes have been around for decades. They are smudge-prone – we know – we kinda understand why – we don’t really care why. Why are we bothering with this? I really really really don’t give a shit. And to anyone who asks why I read the article – I expect Wired articles to be good and to learn something from the articles I read. This article was a waste of time.

  5. Bruce Gordon

    There are more important things than fingerprints, like the slipperiness of the finish that may make the difference between holding your phone and dropping it. Feel the two finishes side by side. Which one allows your finger to slide over it easier? Choose the other one.

  6. Now that “Honey they took away the earphone jack” saga is out of the way, anything’s good for click bait these days.
    Remember when there were real journalists and real news?

    But since we’re discussing this earth shattering subject, I wonder if a slight coating of automobile wax or polish will help avoid the smudges? It works on my shiny black car and there’s no bigger fingerprint and dust magnet than my car.

    The other answer is Steve Jobs’ famous line from the days when everyone lost contact from the outside world because of antenna-gate: “Don’t hold it that way”

  7. At least it isn’t going to explode in your hand.

  8. You are right, the difference between journalism and housewife gossips are lost to the folks at Wired.

  9. To see New Apple’s latest failed product.

  10. Now this is the New Apple, all show, and no go. Looks great in the box but in the real world just another over priced piece of s*it with lots of fingerprints on it. And it’s only $800 and will be outdated in a year. Go ahead Apple needs your money in its off shore accounts.

  11. Johnmichael Monteith

    Ignoring the question of whether this first-world disaster is news-worthy, did you seriously have an article about how bad something looks without including a single picture as an example?

  12. You are very kind.

    I, on the other hand, am amazed at the amount of non-content Wired is allowed to publish lately.

  13. Stone Edwards

    As I said above: why did you click on and read the article then?

  14. Stone Edwards

    Sooooo why did you read the article then? Personally I found it pretty interesting

  15. Drew Lakebrink

    Article Summery: people are dirty and that transfers over to things we touch.

    Also, who really cares.

  16. I’m sorry that I can give you only one up-vote.

  17. Why Finger Smudges Look So Much Worse on the Glossy Jet Black iPhone 7

    Who gives a shit

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