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Everything you need to know about Corning Gorilla Glass

Headquartered in Corning, New York and founded in 1851 – yes, the company is over 160 years old – Corning Incorporated is one of the world's leading innovators in materials science. The Fortune 500 company operates in diverse market segments like Optical Communications, Display Technology, Specialty Materials, Life Sciences, and Environmental Technologies with expertise in specialty glass, ceramics, and optical physics.

However, the product that has brought them instant recognition in technology space has been Gorilla Glass, the damage-resistant cover glass used in thousands of mobile devices.

I visited the Sullivan Park research facility in Corning, NY earlier this year to find out more about glass strength, damage resistance, and of course, Gorilla Glass, and how it fares against other chemically strengthened glasses in the market. Asahi Glass Co.'s Dragontrail and Schott AG Xensation are the other players in the market that offer strengthened glass for smart devices.

Why Gorilla Glass?

As leaders in 'glass', Corning saw that the consumer electronics industry required a tough and durable cover glass driven by the use of touch. Of course, damage resistance and design capabilities are key product requirements. Such a product would help OEMs differentiate and enhance user experience offering thin and light displays with optical clarity offering flexibility in device design.

In less than ten years, Corning Gorilla Glass is now an industry standard with significant brand awareness. Many smartphone buyers look up the specifications sheet to spot 'Gorilla Glass' making it an important consideration when making a purchase decision. Gorilla has been designed into more than 1,800 models, and an excess of 4.5 billion devices have been released in the market with Gorilla Glass!

According to the company, over 40 OEMs have designed models with Gorilla Glass and many have used the Gorilla Glass brand as a key selling tool. These include major device brands like HTC, LG, Acer, HP, Asus, Dell, Samsung, Lenovo, Microsoft, and Motorola as well as Chinese giants like Meizu, ZTE, and Huawei, and Indian players like Micromax.

Recently, Ford Motor Company announced that it will be using the material for the windshield, the rear window, and bulkhead on its Ford GT supercar.

What is damage resistance?

During my visit to the Corning Labs (Corning has many other labs, including two research facilities - Corning Technology Center in Shizuoka, Japan and Corning Research Center Taiwan in Hsinchu, Taiwan) in freezing February this year, I spent some time with the researchers who work on materials science and Gorilla Glass.

Of course, the first step was to understand 'damage resistance' – the ability for a material to limit strength reduction due to flaws evaluated by measuring the retained strength of a material after damage has been introduced.

To understand damage resistance, we did tests on different types of Gorilla Glass compositions and traditional soda lime glass. Soda lime glass is similar in composition to the glass found in most windows today.

Abraded Ring-on-Ring (ARoR) test involved abrading the surface of the glass with silicon carbide particles to simulate in-field impact events, followed by a standard Ring-on-Ring (RoR) test to measure retained strength. Scratch Ring-on-Ring (SRoR) involved scratching a glass surface followed by a standard RoR test to measure retained strength.

While the theoretical strength of glass is very high, its strength is greatly reduced when a defect or flaw is introduced. Glass almost always breaks from a surface flaw that is subjected to tensile stress (pulling apart/stretching).

How is Gorilla Glass made?

Corning's proprietary fusion manufacturing process produces a thin sheet cover glass with pristine surface quality, outstanding optical clarity, and inherent dimensional stability. According to the company,

The process begins when raw materials are blended into a glass composition, which is melted and conditioned. The molten glass is fed into a trough called an "isopipe," overfilling until the glass flows evenly over both sides. It then re-joins, or fuses, at the bottom, where it is drawn down to form a continuous sheet of flat glass that is so thin it is measured in microns. The glass is untouched by human hands or anything else that will introduce flaws into the surface.

The composition of Gorilla Glass enables a deep layer of chemical strengthening through an ion-exchange process where individual glass parts are cut from the 'mother sheet' and undergo an ion-exchange process.

Ion exchange is a chemical strengthening process where large ions are "stuffed" into the glass surface, creating a state of compression. Gorilla Glass is specially designed to maximize this behavior. The glass is placed in a hot bath of molten salt at a temperature of approximately 400 degrees Celcius. Smaller sodium ions leave the glass, and larger potassium ions from the salt bath replace them. These large ions take up more room and are pressed together when the glass cools, producing a layer of compressive stress on the surface of the glass. Gorilla Glass' composition enables the potassium ions to diffuse far into the surface, creating high compressive stress deep into the glass. This layer of compression creates the surface that is more resistant to damage.

Evolution of Corning Gorilla Glass

Corning experimented with chemically strengthened glass in 1960, as part of a 'Project Muscle' initiative. Marketed as Chemcor, the 'muscled glass' was used until the early 1990s in commercial and industrial applications, notably in 1968 Dodge Dart and Plymouth Barracuda racing cars, where minimizing the vehicle's weight was essential.

In 2005, investigating whether the type of tough glass could be made thin enough for use in consumer electronics, Corning used this glass technology to invent a brand new glass composition, Gorilla Glass.

Corning Gorilla Glass was commercialized in 2007, and as I discovered myself in the lab tests, it outperforms plastic covers for scratch resistance as well as strengthened soda lime when damaged.

It was followed by Gorilla Glass 2 in 2012 that offered increased damage resistance or thickness reduction. Compared to the original Gorilla Glass, Corning Gorilla Glass 2 provided over 25% increase in damage resistance. OEM customers could choose to use the improved performance in one of two ways - higher retained strength at same thickness or up to 20% reduced thickness with equivalent retained strength.

In 2013, Corning Gorilla Glass 3 with Native Damage Resistance arrived. Compared to Gorilla Glass 2, Gorilla Glass 3 with NDR offered improved scratch resistance, reduced scratch visibility, and improved retained strength after scratch.

Gorilla Glass 4

According to Square Trade Inc., "You are 10x more likely to break your phone than lose it or get it stolen." Broken mobile devices are a common problem, and overwhelmingly the top issue consumers want improved in their displays.

Gorilla Glass 4 was formulated to address breakage and delivers the highest damage resistance to date, and has the capability to significantly improve device drop performance. The company claims that Gorilla Glass 4 withstood such drops up to two times better than competing glass designs. When it comes to drop performance on rough surfaces, while Gorilla Glass 4 survives up to 80% of the time, soda lime glass breaks nearly 100% of the time.

Advantages of Gorilla Glass

Of course, the primary advantage of Corning Gorilla Glass is damage resistance. Gorilla Glass is chemically strengthened through an ion-exchange process that creates a deep compression layer on the surface of the glass substrate. This layer acts as a sort of armor to reduce the introduction of flaws.

Also, the process produces glass with exceptionally clean, smooth, flat surfaces and outstanding optical clarity making it a great cover sheet for touch screens. It's tough enough to handle the surface pressures intrinsic to these devices, and exceptionally thin to enable more sensitive and accurate responses.

Gorilla Glass can be produced in thicknesses ranging from 0.4 mm to 2 mm, and even at 0.4 mm the company claims that the Gorilla Glass retains a performance advantage over many other cover materials.

40 Comments
  • Scratch resistant? Posted via the Android Central App (V10 or 5x)
  • I think making it more Crack resistant is better. Isn't scratch resistant a specialty of Sapphire Glass.
  • I love the article.but I'm still going to use a glass screen protector. Posted via the Android Central App
  • You're not alone
  • That was a great article. I'd like to get a tour of the Corning lab myself. Posted via my Moto X Pure Edition using the Android Central App
  • I wonder if Corning is working on shatterproof display technology like Motorola used in the Droid Turbo 2. It would be great to get that technology on phones that appeal a wider range of people.
  • Do we know for sure that Corning didn't manufacture that glass for them? It's best to assume I'm being sarcastic. if I'm ever serious I'll type "/s" to make it clear.
  • It's branded as Moto Shattershield and as far as I can tell, it was developed in house by Motorola.
  • Developing such a glass for use on a wide range of devices offered by Apple, Samsung, HTC, LG would place a dent in case/screen protector accessory sales and insurance or repair plans. Imagine devices stopped having screens shattered and there was really no reason to get them repaired other than a manufacturer defect?
  • Moto uses plastic
  • Good article, thanks. I'm going to visit them myself next time I can. Should be fascinating. Posted via the Android Central App
  • Wiping the phone clean with your shirt while grains of sand are present on the screen or your shirt or dropping the phone so that it lands face down while simultaneously impacting nearer the edge of the screen are the mortal enemies of GG3 and GG4.
  • Not a single scratch on mine in nine months. Galaxy S6 Edge +
  • My grandma's S6 Edge+ is super super scratched. How odd. AT&T Galaxy S7 Onyx Black with Unlimited Data
  • Does your grandma have a cat? Just curious.
  • No, she has a shih tzu and a tea cup maltese, these two rat dogs. I wish she had a cat or 7. AT&T Galaxy S7 Onyx Black with Unlimited Data
  • Does your grandma wear diamond earrings? If I'm not careful, I get tiny, fine scratches on my phone display from the small diamond stud earrings I wear.
  • Hate to say it but this article is basically product placement with a huge amount of text, photos and graphics that looks like it was taken directly from a Corning marketing brochure.
  • Didn't work on a 3" drop from my pocket onto a concrete seat.
  • Alternatively, you put 6 post screws through the case with some rubber gaskets and replace the screen when it breaks using a simple screwdriver. I don't understand why no one is angry at companies who design products which doesn't allow customers to repair their own products. 6 screws and a proper gasket will not add much thicknesses, still look cool, and allow to replace the screen and case at will. Posted via the Android Central App
  • Except the glass is usually fused to the display itself, so you wouldn't just be replacing the glass. Posted from someone's Note 4
  • How much would it cost to replace such a display/screen component? Even if it is over $100, I still think it is worth it.
  • Because then there would be no incentive to buy a new phone. The whole reason that batteries and screens are no longer user replaceable is because broken phones are what drive device sales.
  • Corningware, where it all started. Who remembers this oven safe AND stove top friendly cookware? Hard to find now, but the classic cookware has a "flame" in the middle of the logo. From freezer to flame was their motto. With their Gorilla Glass, I expect nothing less. I have had me original Samsung Galaxy Gear, without a screen protector, for almost, what 3 years now? Not a scratch. Oh, yeah, I also work in retail, at a major department store where it gets banged up each day. Posted via the Android Central App
  • Well 9 years after it was first introduced, I would have expected such improvements as to make GG virtually indestructible, but that's hardly the case. Phones are still shattering and scratching like crazy. Look at some easy tests done with the S7 edge. I've been lucky so far because I treat it like a baby, but on my first accident, I'll be very scared.
  • As if it is soooooo easy to make a thin glass indestructible. smh ..... Maybe you should apply for CEO. They obviously aren't doing as well as they could.
  • The glass *is* getting comparatively stronger, but instead of using that increased strength to improve durability, they're using it to shed weight. The manufacturers want to make the thinnest, lightest device they can, and that includes using paper-thin glass, metal, plastic, and other materials. It increases profit margins, and drives sales with those consumers who want the newest, coolest gadgets. It's an added bonus that the ultra-thin and ultra-light materials aren't any more durable in the long run, because broken devices are the other big driver of sales - especially among the consumer group who will use a particular device until it is beyond repair, completely obsolete, or both.
  • So a glass protector is an accessories or a must-have? Hmmmm Posted via the Android Central App
  • This is a placement ad IMO. Plus it's honestly disappointing that after this long, we still have to use cases and screen protectors to protect this fragile glad on MOBILE devices. Why not start with durable plastic and work towards greater thinness and clarity? Moto?
  • Informative article, but I still use 9h glass screen protector on my 6p.
  • Yeah, keep giving your money away for screen protectors. Two years of Gorilla Glass on 4 phones and never a single scratch on any of them. Babied phones? Not at all. I simply "use" them. GG has made screen protectors the equivalent of snake oil, but then it's always been purchased by someone.
  • I've used Galaxy phones for years and never got a single scratch on my screens. When I got my GS6 EDGE + last year, T-Mobile (store)sneakily put one on and charged me for it. It was crazy expensive and I noticed it every time I saw it. I resisted tearing it off for about a week before I couldn't take it anymore. I ripped off that piece of snake oil and enjoyed a pristine screen until I upgraded to my GS7. I paid attention and made sure they didn't put that crap on my new phone. I have a lot of confidence in gorilla glass, I feel that it really has made screen protectors obsolete. Heck I have had a Samsung Gear 2 Neo ever since it was released last year. I am a janitor where I work so believe me it gets banged around a lot. Not a single scratch on the screen! Yes I've hit that screen extremely hard at times and the screen is as pristine today as the day I bought it. One more thing I want to mention. Before I took the janitor job I was in manufacturing where they use air powered tools. I had incidentally bumped my screen into the bit in the overhead air gun causing the bit to spin right on top of my Neo's screen. If that's not a testament of the strength of gorilla glass, I don't know what is! Posted via the Android Central App
  • Whatever, everybody likes to put a tempered glass on their phones! Posted via the Android Central App
  • Speaking of gorillas, why they have to kill Herembe!
  • IF Gorilla Glass is the bee's knees, then why are some many manufacturers and carriers offering accidental damage coverage from drops? I bet if you look at repair statistics, the #1 cause for repair is shattered screen. The most expensive component on the phone is the screen w/ lcd that's fused together. My screen cracked on my S6 Active 1 month after I got it and Samsung wanted to charge me $317 (including tax) to repair it. It took several days of complaining about the device durability and negotiating with the service center and I ended up paying $77 out of pocket.
  • Very informative article. I was familiar with the manufacturing process, but not some of the history. I don't get the comments about a placement ad, as pretty much every flagship uses GG anyway. Raise your hand if you go into a phone store and say "I have to have a phone with Gorilla Glass!". I've never asked for it by name, but GG is always a plus. I'm a two phone person, with an iPhone in my left pocket and an M8 in my right. Comb and paper money with the iPhone, coins and keys in with the M8... and the iPhone gets scratched up. Go figure! Now shatter resistance is another aspect, and the ultimate resistance to that requires malleability. Unfortunately, a material's ability to be deformed and recover does not go together with very high surface hardness. This is why shatterproof screens are usually plastic, and must be used with a screen protector to prevent scratching. Glass is glass for now, and every phone with a glass screen will break if dropped face down onto a concrete surface.
    And yes, logic usually would dictate that harder screens are more likely to shatter, but you also have strength playing a part. Drop an iPhone 5c and an HTC M9, and the 5c will break a MUCH lower impacts then the M9. The biggest reason for this is that the 5c glass is in the middle of the road: not hard enough to resist scratching, not strong enough to resist flex, and not soft enough to take an impact without breaking.
  • I'm fascinated by the article but it really does look like a big ad. On a side note, it's still just glass at the end of the day, so continue to take care of your phones and use screen protectors when possible.
  • It's all just commercial talk, marketing talk to be honest! If you watch JerryRigEverything, you'll know that all tempered glass all relatively have the same hardness, around 7 on the Mohr scale. The difference is, Corning has more money for advertising compare to other manufacturers.
  • If you're still thinking that Gorilla Glass can't be scratched with day to day use you obviously haven't taken a closer look at your screen in direct sunlight. All of my devices until now have had minor scratches from really careful day to day use and all of those phones had Gorilla Glass. Now, the scratches are only visible in direct sunlight when held at the right angle, but the scratches are still there. Once you notice a scratch you're going to keep noticing it. Posted via the Android Central App
  • The only improvement in phone screen technology worth talking about is when it is shatterproof. Thank Motorola for this advancement . Although their screen on the Droid Turbo 2 / Moto X Force is guaranteed not to crack or shatter, it still may scratch. In this case a screen protector is helpful. I took the drop test at one of the Motorola stores in Chicago and I couldn't break it. If GG4 can do the same, then it would be worth talking about.