Apple Watch and durability: How tough are Apple's finishes?

Most of us have seen how an iPhone (sans case) tends to look after a year of daily use - all of those dents, dings and scratches occur to a device that lives primarily in your pocket, in your hand, or on your desk. A watch leads a far less privileged life, swinging exposed on the wrist, open to a tremendous amount of incidental daily contact.

Greg Koenig is co-founder of Luma Labs. He hews atoms into objects you may find useful. In this capacity, he's gained expertise into manufacturing and materials, and has been gracious enough to share those with us in this overview of the Apple Watch and its potential durability. In the part, he covers the durability of Apple's aluminum, stainless steel, and gold cases. In part two, he covers the durability and tradeoffs between Apple's Ion-X and sapphire screens.— Ed

It's no surprise that questions are being raised about just how durable each variant of the Apple Watch will be, given that people are now considering putting down real money for them. The best way to answer such questions is to wait and see how the first wave of watches do in the hands of real people. Yet it's not unreasonable for potential early adopters to want at least some idea before they buy. Lucky for us, Apple is using materials and techniques that have been standard for wristwatches going back a few decades, so we can make some educated, experience-driven assumptions about how the watch variants will fair on our wrists soon.

The Edition

Apple Watch Edition is made from 18kt gold. While there were some pre-launch contentions that the Edition models would use some revolutionary tungsten-ceramic-matrix wizardry to improve hardness and durability, none of that came to pass. By definition, 18 karat gold is comprised of (at least) 75% pure gold by weight, while the remaining materials in the alloy exist to modify the color, increase the hardness and/or make the gold more workable. Apple claims to be using a "proprietary" alloy, but that is just marketing speak - every large manufacturer of gold has their own metallurgists on staff, alloying facilities and recipes. Consequently, every manufacturer of gold watches claims their alloy is more durable, resilient and lustrous than the competition, with very little quantifiable data or 3rd party testing to verify such claims.

Durability wise, gold is not the ideal material to manufacturer a watch with; it is soft and prone to being dented and damaged quite easily. On the other hand, repairing gold items is relatively straightforward, and any jeweler or watchmaker worth their salt can readily polish out the vast majority of accumulated daily scratches and ticks. Severe dents and gouges are also easily repaired simply by filling in the defect and polishing the area smooth - a process readily performed by a quality jeweler.

As to the clasps on the Edition models, it remains to be seen if they can be removed from the leather strap. Leather watch straps see tremendous wear and tear, most have a service life of 2-5 years, depending on how rigorous the owner is with them. Consequently, the metal hardware on leather straps is easily removed and transferable to a replacement strap, especially on modern watches where the design of the clasps may be closely related to the case of a watch (and therefor, difficult to replace once out of production). With the Edition models featuring solid gold clasps, it would be crazy to think replacing a worn leather strap would require the purchase of new clasps, but we are talking about Apple here, so who knows?

The Watch

The mainline stainless steel Apple Watch cases are made from the most common watch alloy in existence, 316L. While Rolex will claim their use of 904L stainless is superior to 316, the reality is that the differences are irrelevant in everyday use. 316 alloy is strong, durable, plenty corrosion resistant, and polishes to a beautiful luster.

In general, you can expect the Apple Watch models to wear about the same as any other high-quality stainless watch, with perhaps slight advantages afforded by both the smooth case profile (less edges to catch and ding) as well as the profiled forging process. Stainless is slightly softer than anodized 7000 series aluminum, but the polished surface and dense grain structure should help the occasional impact glance off the surface with little/no damage. It also helps that the Apple case is fully polished — the surface leaves little traction for an impacting object to hit, and the shine actually helps to make minor scratching more difficult to see.

This also brings us to the Link bracelet. There has been much debate about Apple's choice to use a brushed (small, directional micro scratches) surface on the bracelet, in contrast to the polished surface of the case. Every high-end link bracelet I've ever seen or owned has featured a brushed surface and this is (to me) vastly preferable. The faceted angles of a link bracelet will catch reflections from nearly any angle, causing the watch to be excessively bright. More importantly, bracelets receive the most wear and tear of any component on a watch, and brushed surfaces do a much better job of hiding the daily dings than polished ones.

For stainless steel watches, refinishing is a routine service often done during battery changes (quartz) or movement servicing (mechanical). The preferred method for refinishing a watch is to do so with disassembled components (especially on watches that feature both polished and brushed contrast surfaces), but a basic polishing can be performed on an assembled watch. Talking to a couple of watchmakers, they felt that the stainless watch could have daily scratches removed, but they would prefer to have access to special tools to protect the edges, crown, and buttons (lest polishing break the hard edges in these areas). The Link bracelet, on the other hand, should be relatively straightforward to touch up and remove daily wear marks.

Space Black Watch

Black watches do not have an illustrious history in the world of quality timepieces for two reasons.

  • The highly "technical" look contrasts with casual wear but is also too much for formal attire.
  • Plating technologies left a lot to be desired, and older blackened steel watches quickly looked worn after just a few high-contrast silver dings and scratches.

With the vast majority of "luxury" watch buyers only owning one or two timepieces, shoppers generally look for watches that can be used for a lifetime, and for a broad range of occasions. Black watches have had trouble offering that.

Enter two technologies: The Physical Vapor Deposition (PVD) plating process and Diamond Like Carbon (DLC) materials.

In the basic PVD process, a part is cleaned thoroughly and placed in a vacuum chamber, along with a consumable sample of plating material. Once the air is evacuated from the chamber, the material sample is vaporized by a heater and eventually condenses on the target part. PVD is a highly competitive, advancing technology with applications across many fields — anti-reflective, UV blocking, scratch resistant sunglass coatings? PVD — and the process is often heavily modified. The gist remains the same.

The PVD process is used to create a vast array of coatings, but the current gold standard for hardness and wear resistance is DLC. Essentially, a DLC coating is a 1-3 micron layer of carbon that self arranges into a structure similar to that found in a diamond, thus imparting some of a diamond's surface hardness properties. In fact, many of the attempts to create synthetic diamonds revolve around modifying the basic PVD DLC process in order to "grow" a stone. The term "DLC" itself isn't just one kind of coating, there are 7-8 different basic chemistries, and each manufacturer of equipment and service provider often creates their own proprietary recipe and processes. (Tungsten DLC, for example, deposits a layer of tungsten on the part before the DLC layer is applied, promoting better adhesion).

So just how tough is DLC? The best way to put it is that the watch industry is a second or third tier user of DLC coatings. The vast majority of research and application of DLCs goes into highly engineered components that depend on DLC's hardness, friction reduction, corrosion resistance, and tribology advantages. (That's the study of how one material interacts with another during contact and sliding.) You'll find DLC coatings on shock absorbers and engine pistons in F1 cars, across the leading edges of fan blades in jet engines, coating critical medical implants, and the cutting tools inside the CNC mills and lathes that made the Apple Watch itself. (DLC extends cutter tool life, improves cut quality and allows for dramatic feed/speed increases.)

How this all affects the Space Black Watch is entirely dependent on the quality of the DLC coating Apple is using. Like all things in manufacturing, there is a pretty broad range of quality you can wring out of a particular process. We've seen factory and aftermarket DLC watches that seem impervious to damage, while others have flaked off with minor use. It is a very safe bet that Apple's DLC is pinned at the better end of spectrum, and that would mean the Space Black Watches will be the most durable models of the watch in day-to-day use.

One downside of the DLC process, though, is that any damage to the surface of the Space Black watch will, for all practical purposes, be unrepairable. To re-coat the DLC, you would need to strip the watch to it's bare case and have the entire coating re-applied. While you probably have a PVD shop in your area with DLC capabilities, they would need to develop a strategy to coat your watch (how it is held in the machine to provide an even coat), as well as figure out the proper recipe. The costs to do this for a single watch would quickly exceed the price of simply replacing it.

The Sport

Aluminum is, generally speaking, about the least suitable metal for creating a watch. Not only is standard aluminum quite soft, but it must be plated to avoid oxidization, leading to many of the same problems as older plating technologies for black steel watches. Apple is acutely aware of this and also has more experience selling and servicing aluminum products than any other company. That's why they appear to have taken some interesting strategies with the Sport variants.

First, Apple has chosen to use a harder aluminum alloy — 7000 series. While the standard 6000 series aluminum is plenty strong for a watch, 7000 series aluminum offers roughly double the hardness and twice the tensile strength, approaching figures typically seen in mild steel. This means the anodized surface will have a much harder underlying structure to resist scratches and dents.

More importantly, Apple has deployed some advanced anodizing technologies. Anodizing is an electrochemical process that "grows" a uniform layer of aluminum oxide across the surface of the part, and there are a number of different methods for making this happen. In anodizing, the raw aluminum part is placed on a metal rack and (after a quick acid bath to clean the surface), is dipped into a tank of sulfuric acid. While in this tank, a positive electrical current is passed through the metal rack and the anodizing parts, while the negative end of the circuit is located in a metal plate inside the tank. This current causes oxygen molecules in the sulfuric acid to bond to the outer layer of the aluminum, creating a skin of aluminum oxide - a ceramic material that is far harder than the underlying aluminum.

There are many specifications for anodizing aluminum that lay out the exact chemicals to be used and the thickness/density of the anodize to be applied to a part. The vast majority of aluminum products you see are Type II anodized — low currents are applied, near room-temperature sulfuric acid is used, and the anodizing layer is typically only 0.0005" thick. (That's about 1/8th the thickness of a sheet of copy paper.) Type II anodizing is quick, requires little power, and provides sufficient protection while still allowing the aluminum to be dyed in a variety of colors.

In looking over some current Apple products with anodizing process experts, we've noticed a substantial durability increase, starting with the introduction of Space Gray with the iPhone 5s. Normally, this would be attributed to Apple switching to a process known as Type III anodizing, where higher current and near-freezing sulfuric acid is used to grow a layer of anodization well over 0.001". Type III anodize is very (very!) durable, but that thick layer tends to actually grow parts out of dimensional tolerance, haze over any polished surfaces and soften edges. However, we see none of the typical signs of Type III anodizing in Apple's current products. More interestingly, using calibrated anodization layer thickness measuring tools (ones currently certified for aircraft component production processing) we could not measure the thickness of my Space Gray iPhone 6 anodizing.... How?

The best theory that we've developed is that Apple is using a combination of tricks to achieve anodizing superior to the typical processes everyone else employs, combined with post-anodizing processing. Most likely, Apple uses the high currents and chilled baths of Type III anodizing to produce a dense, thin layer. Before sealing, this layer gets stuffed with dyes, optical brighteners, and hardening elements to further enhance the surface properties (hence Space Gray's almost silver appearance, the bronze undertones of the Space Gray Sport, and the clear silver on the standard Sport).

Whatever Apple is doing, I found myself impressed. I was prepared to write this piece with the conclusion that the Sport watches would be "essentially disposable" in the wear and tear department, but I made a field trip to all 3 Apple Stores in the Portland area. With the Watch Try On tables empty, the employees were happy to show me all 32 Space Gray Sport watches Apple has in the Portland area, and they were all still flawless. It's important to remember, these watches have been on-duty now for 10 days, being handled by literally hundreds of people. Even without rough handling, I would expect the anodizing to just start showing signs of wear on the edges, but every watch I inspected still had a flawless finish.

Still, as impressed as my field trip made me, the fact is, Apple Watch Sport will likely be the most delicate of the models when it comes to overall durability, especially the Space Gray models (like the one I ordered). Even without dents and dings, anodizing tends to be extremely thin at sharp edges. I fear the Digital Crown's grippy, laser cut serrations will show signs of use fairly rapidly. Apple could prove me wrong here — they clearly have some very smart anodizing experts on staff, lots of experience with the process and the resources to push the science forward.

Greg Koenig

Co-founder of Luma Labs. he hews atoms into objects you may find useful. Follow him on Twitter at @gak_pdx

  • I'm glad I'll be getting AppleCare+. . . . Please, Sport Watch, take a licking and keep on ticking.
  • I doubt AppleCare will cover cosmetic damage. Sent from the iMore App
  • applecare+ covers 2 cases of damage but the deductible will be high enough that people won't be returning it for nicks and scratches.
  • That's pretty much what I'm figuring. I have Apple Care+ on my Stainless Steel Apple Watch but I'll only be using Paying that Apple Care + deductible in dire situations. I'll embrace the nicks & scratches; it gives the watch character. Sent from the iMore App
  • "Damage" yes, but cosmetic? I don't think so either. If you can buy a Space Black watch and just turn it in for a new one the first two times it gets scratched that would just be insane. You can't get a new MacBook if you scratch your current one, Apple Care or not.
  • Yep. I'm pretty sure they mean cracked screen, broken crown or button, but not normal wear n tear. If I scuffed my 6 plus and tried to get a new one they would laught and tell me to gtfo. Sent from the iMore App
  • That is not insane. That is just good customer service. You have to remember they have a really high margin on these products, and the Space Black watch will not have that many scratching events to begin with. If only a small percentage of people even need to replace one case it makes sense for Apple (from a customer experience standpoint) to do this even for cosmetic only damage... Not to mention that Apple Store employees always seem to have leeway to replace a product for any reason.
  • Very interesting read. Much thanks, Mr. Koenig (even your name sounds so engineer-like).
    I had a motorcycle that came with DLC coating in the front forks. Interesting to see it being used here as well. Here's to a titanium nitride coated Inconel smartwatch in the future =P
  • I don't understand these statements: "Stainless is slightly softer than anodized 7000 series aluminum..." Following this he writes, "7000 series aluminum offers roughly double the hardness and twice the tensile strength, approaching figures typically seen in mild steel." So it sounds like the aluminum is harder than stainless steel but both are softer than mild steel. With that, the conclusion doesn't make sense to me. How is the aluminum series less durable than the Stainless Steel series when the basic 7000 aluminum is harder? Here's another amazing piece that seems to indicate the Aluminum is the best material for the watches!
  • I'm guessing you already realized that the Atomic Delights piece was written by the same author as this one?
  • Whoops! I didn't realize that! Don't know whether to be embarrassed or flabbergasted. I read that one a bit back and was feeling a bit of Deja Vu.. It's funny how I concluded different opinions from the same guy however!
  • Umm, so the confusion is on me and not you! I'm a bit of a ham fisted writer! Here are some raw numbers (off a few points because this is from the top of my head). Vickers is the scale used to measure hardness of metal. 6061 Aluminum = 82 Vickers 7075 Aluminum = 172 Vickers 316L Stainless = 154 Vickers All of those are the raw, unhardened material. Anodizing is way high on the vickers scale (depending on how thick, dense the layer actually is), but it is such a thin layer that any vickers test tends to bust through the anodize and damage the underlying aluminum, so it isn't a 1:1 test. Also, we don't know if Apple is hardening the 316L or how the forging improves the hardness in this particular application. I was trying to convey that 7000 is definitely WAY harder than standard 6000 series most aluminum stuff is made out of.
  • If I'm understanding this correctly, the 7000 series aluminum, on its own without anodization, is about as strong as mild steel. When anodized, however, it gets closer in hardness to that of stainless steel, due to its oxidized outer layer. Sent from the iMore App
  • I found the wording confusing as well. My guess is that an anodized aluminum product is more likely to show wear, especially at the edges as explained in the article. I have a steel watch I've worn daily for many years and you have to look at it closely to notice the wear. Additionally, a steel watch can be easily buffed back to a like-new finish while anodized aluminum is not cost effective to refinish.
  • After reading this I feel reassured that my Apple Watch purchase should be durable enough for my rough and tumble lifestyle. At least it will be better than all the other watches I have owned. I still dislike the idea of needing Applecare + for a watch though. I may get it, just because I often accidentally submerge my devices in water.
  • It would probably survive an accidental submersion because its water resistant enough to take a shower with.
  • Apple Watch is IPX7 rated, so technically you can submerge it for up to 30 min in 1 m of water, although Apple doesn't recommend it for some mysterious reason.
  • Great piece, Greg! Im guessing the editors stuck you with that lead sentence. Watches? Most abuse? Really? Not linesman pliers, Leatherman, or Barlow lockback? EDC is a "different strokes, different folks" kinda term, I guess.
  • I'll confess, that was all me and not the editors. The way I figure it, we're talking daily, unintentional wear and tear here. My Leatherman and my Microtechs take a harder beating, but that wear and tear happens because I'm specifically using them as hand tools (or abusing them, most of the time). I won't be using my Watch to deliver impact blows on the cheater bar to get a collet off a milling tool! Otherwise, my Microtech lives in my pocket 95% of the time, while the watch is swinging around town on my wrist, hitting door jambs, bumping on tables, getting squeezed against hard surfaces every time I type. So in daily dents and dings, I think watches do take more abuse than most EDC gear for most people.
  • Just want to add - Aluminum sold me on its weight - not its cost. The only way I'd pay for a better alloy is if it were as light or lighter than aluminum (Liquid Metal?) From that perspective, gold is by far the worst material for watches. If I was an alien, didn't know the value of materials, and was given a choice of a free Apple Watch of choice - I'd choose the lighter-weight metal with the "less-blinding" and more natural looking silver satin finish along with the comfy and color-matched black rubber band. Yup - silver sport with a black band. A twilight-zone episode I suppose ;)
  • I agree with you on the satin finish. I love the way it looks. I wonder if apple will make a brushed steel watch or some other non-shiny material in the future.
  • Brushed stainless steel is beautiful. It has an understated quality to it. I feel like Apple chose polished because it bounces light at every angle and demands the eyes attention. Great for getting attention. I'd personally rather have people focusing on my eyes rather than my watch. The polished look also has a sort of plastic-like look to me.
  • I, also prefer brushed stainless steel. I don't believe I've ever owned anything made from polished stainless steel, but it definitely looks better than aluminum! Sent from the iMore App
  • Agree that a brushed case is nicer than polished.... but I work in manufacturing and can tell you that getting a consistent brushed finish on a product, over and over, is difficult and will result in more scrap parts. It is far easier for mass production to mechanically polish the hell out of the metal. The reason is that you can polish out any minor surface nicks/scratches during the manufacturing process, but you can't hide those by brushing. So I don't believe Apple chose polish over brushed for Bling purposes, no.... it's for more efficient manufacturing. Plus, the Sport will outsell the Steel by 2 to 1 so if Bling was the reason, you'd think they'd Bling up the Sport model more.
  • One problem with brushed finishes on a watch case is that the profile of the case (being all curvy and with minute details) is very hard to refinish. The Link bracelet is pretty easy to get under a 3M Scotchbrite wheel and re-brush because the surfaces are flat and easy to access. The watch case? Not so much. Watchmakers during refinishing usually have to resort to all sorts of crazy intricate masking and delicate finishing operations to get the job done (Rolex and Omega both have brushed sections of the case to help lead into the transition to the brushed bracelet).
  • i don't mind normal wear on a watch, i can't wait to see how well it wears. i'll find out in june.
  • Good article. Especially the part that says "One downside of the DLC process, though, is that any damage to the surface of the Space Black watch will, for all practical purposes, be unrepairable". This is good info to have when considering the watch finish since AppleCare+ only gives you coverage for two incidents. Sent from the iMore App
  • Great info! I love these articles with lots of actual information. The info about the anodising and the coatings is spot on as far as I can see and over my head anyway, but the bit at the beginning about the consistency of the gold gives me pause and I wish the author could elucidate. He says that the gold is not "some revolutionary tungsten-ceramic-matrix wizardry," but every other review of the watch has said that the gold does use ceramic in a matrix. Are we to understand that this is not true? Or that it's true they are using ceramic, but that it's not "wizardry"? Secondly, he states that the gold is "75% pure gold" which is actually different from what everyone else is saying which is "75% pure gold by weight." In the absence of the "by weight" qualification, the default definition would be by *volume* which is a different thing altogether.
  • In every Apple document I have read, they always use the term "gold alloy", e.g.: " entirely new alloy...". The term "alloy", I believe, refers strictly to metal mixtures, excluding the use of ceramic materials. I think that the "gold-ceramic wizardry" was an unconfirmed rumor started by the uncovering of an Apple patent regarding such a material; presumably, Apple has decided not to use it for the Edition gold.
    Regarding the weight/volume discussion, Apple always uses the "karat" term (e.g.: "A more solid 18 karats."), which is strictly a w/w unit. So, when the author says "18 karat gold is comprised of (at least) 75% pure gold", one would presume that he too refers to w/w units.
    However, I'm curious: why, in absence of other specifications, "%" is "vol%" and not "wt%"? Due to everyday use for alcoholic beverages and other solutions?
  • Pre-Watch event, we had some conjecture from an Apple patent filing that they were (perhaps) going to use some crazy ceramic matrix gold technology. This also squared with something we've seen other watchmakers using (Hublot's Magic Gold). None of the Apple marketing material has indicated they did this however. Watching the craftsmanship videos, the gold process Ive narrates is actually pretty bog-standard stuff; the ceramic matrix patents all require complex sintering and compression processes with powdered metals to build the components. Also, added the "by weight" to the 75% pure gold. Having said that, the karat standard is intrinsically measured by weight and not volume - that is how the ceramic gold advances can get away with saying they are still "18kt."
  • I would hope it is as strong as any other watch. Back in the day when I did wear a watch I never had an issue with it breaking. The battery would die if anything.
  • What about the displays? What's keeping them from being a scratched up mess?
  • Not rubbing it with Sand paper. ;-). Think of the watches you owned before. Has that happened? Not for me. Even when I was a crazy kids and never took it off and did everything with my watch.
  • Keep the glass one under your sleeve as much as possible. I suppose the Sapphire one can also function as a hammer though!
  • Actually sapphire, while super scratch resistant, is actually fairly brittle. Use it as a hammer and it will shatter. Sent from the iMore App
  • I was never good with jokes...
  • Yes, the watches I have owned have ended up at some point with a scratched display...
  • What's all this talk about advanced manufacturing processes and material science? I thought Apple did nothing but take off the shelf everything and make fancy commercials!
  • Not sure why the /s. That's pretty much what they did. lol. Is it quality materials? For sure. Did they invent new material? Absolutely not. Sent from the iMore App
  • The /s is needed if you understood what Apple does.
    They invent new manufacturing processes all the time and that involves a lot of material science with regards to coatings. Read a book about it. I've read several about Apple and their industrial design division, very interesting. Also, there isn't a single "off the shelf" item on the Apple Watch, not one. Everything was custom designed in house by Apple, so......not sure why you're not sure about the /s.
  • Greg - in this video interview Ive says they didn't just buy a gold off the shelf, that they developed their own and that it's harder than traditional gold. begins at 6 min:
  • quote: "Severe dents and gouges are also easily repaired simply by filling in the defect and polishing the area smooth - a process readily performed by a quality jeweler." Agreed. However, is anyone going to want to risk an ooopsie from a jeweler and have the whole watched gauged?
  • I have a 38mm sport (small wrists) and i have all ready scratched the glass twice and have quite a few dings in the aluminum. Nothing terrible but it really bugs me that it is THIS fragile. I have purchased a defense edge case but after wearing it for a couple days I still like the look of a naked apple watch much more.
  • This has been a dilemma for me from the beginning. I changed the space grey for the light grey and then upgraded to the silver. The silver was 150.00 more because when I bought the light grey sports< i needed to buy a black band as it came in white. I have a stainless steel now with a spigen tough armor case on it but after reading this I am still not sure. I have a week left to change back to sports....
  • I bought an Apple Watch Series 2 Sport, space black. I got it in the mail 8 days ago. It already has a crack in it and I have no memory of hitting it on anything. They're not durable. Also get AppleCare+. Pic: