1 - Introduction
2 - Key Concepts
3 - Gorilla Glass vs Normal Glass vs Dragontrail vs Sapphire
4 - Which Tablets Have Gorilla Glass?
5 - Mythbusters
6 - Oleophobic Anti-Smudge Coatings
7 - Smoothness
8 - Screen Protectors - Do We Need 'Em?
9 - Vibrant Gorilla Glass
10 - Miscellaneous
11 - Summary
The aim of this article is to provide a comprehensive guide to the different types of glass available in tablet computers, without being overly technical. It will include a few videos that illustrate concepts and show exactly what the various types of glass can do. It also includes some information about screen protectors.
i. Glass Shatters.
Look at glass under a microscope and you will find countless tiny flaws and cracks. Every time your car key bangs into one of those cracks, it gets slightly bigger. And so on, and so on, until finally you drop it from all of 2 feet and it frikkin EXPLODES. There are ways to mitigate this in the manufacturing process (e.g. Gorilla Glass) and by buying a screen protector.
ii. Glass Can Be Scratched.
An exploding screen isn't that bad, really, as long as you didn't lose an eye when it happened. After all, you really have no choice but to get a new screen. The REAL point of stress for most people is having that one crack across a part of the screen. It isn't bad enough to warrant getting a replacement screen, and you can actually still use the tablet (or phablet, or phone), but it drives you crazy and makes your life miserable. Scratch-resistance is such a huge topic than Corning's share price went from $1.33 on October 4th, 2002 to $25 on Feb 13th, 2015. Kaching!
iii. Glass is Sexy.
When we discuss plastic alternatives for screens and screen protectors, we have to keep in mind that it just doesn't feel as good. However, this is somewhat subjective and one person's 'plastic screen of crap' is another person's 'this screen is so soft and responsive'. Nothing beats actually holding it in your own two hands.
iv. Fingerprints Are the Worst.
When you're using your tablet, you want to focus your attention on the cat video you're watching, the angry tweet you're writing to a celebrity you disagree with, or the pig you're trying to splat with a bird. The last thing you want is to see your grubby chicken-wing stained fingerprints all over the screen. Some screens are better than others at not looking like an FBI booking sheet.
v. Glass Should be as Transparent as Possible; Unless You Need Some Privacy.
A privacy screen protector reduces the viewing angles where you can see the screen. If you normally set your tablet up in the kitchen and walk around preparing a meal while watching your stories, you shouldn't get a privacy filter. If you often use your device on the train or you have confidential information on your screen, look into the best option for your device.
Gorilla Glass vs Normal Glass
Gorilla Glass is the brand name for a type of strengthened glass manufactured by Corning. It isn't unique to that company, but they definitely made it famous. It is an alkali-aluminosilicate sheet immersed in a hot potassium salt-exchange bath, which sounds like the kind of thing my girlfriend does to herself at the spa, and the main factories are in Kentucky and Asia.
It is more scratch-resistant than normal glass, making it ideal for smartphones - by 2012 it had been used in over one billion handsets.
Gorilla Glass 2 vs 3
On the Mohs Hardness scale (the one where diamond=10), GG2 gets a 6, while GG3 rates 6.7.
In various engineering tests measuring brittleness, toughness and so on, Gorilla Glass 3 was found to be fractionally harder but more brittle. That made it more scratch resistant but more likely to crack under tension after some use. Hence it's recommended to get a screen protector.
Gorilla Glass 3 vs Gorilla Glass 4
In various technical terms like Poisson's Ratio, Shear Modulus and so on, there's not all that much difference between the two. The real improvement in GG4 is the Young's Modulus, which means the glass should be more flexible. It's certainly the case in this video (the black case is GG3; white case is GG4):
As you'll have seen in the video, GG4 should be much more resistant to cracks and scratches and the flexibility is genuinely impressive.
So it's a step forward but drop a phone on its 'face' and it's still likely to shatter - screen protectors help by distributing the impact across the whole area.
Dragontrail vs Gorilla Glass
Dragontrail is a product out of Japan, said to be six times stronger than normal glass. Tests indicate it is better than Gorilla Glass 2 in terms of scratch resistance, but breaks more easily than Gorilla Glass 3.
Sapphire vs Gorilla
Synthetic sapphire is heat-treated to imprive its structure and is highly transparent, which is obviously an advantage when producing a screen. It's also VERY hard. Sapphire glass is rated at between 8 and 9 on the Mohs hardness scale. It has been used by high-quality watches for many years, but watch glass is quite a lot thicker than on a tablet. Generally, it shatters more easily than other types of glass.
One big drawback of Sapphire Glass is that it's very expensive - between 5 and 10 times the cost of Gorilla Glass. It's also two-thirds heavier, and to make it thinner would make it weaker. Given screens of the same thickness, Gorilla Glass is less brittle.
Corning have a list here.
Yes, there is! It's pretty great. Part 1 is probably the most visually interesting nine minutes of information about glass you'll ever see, but it's more of history lesson. Part 2 (shown here) goes into the durability of Corning glass vs other types of glass (like soda lime glass, used in bottles and jars) so it's more useful in the context of this article.
The 'oleo' in oleophobic comes from the word 'oil' - so it's literally a substance that 'fears' oil. Guess what is oily? Your fingerprints. Screens or screen protectors that have oleophobic coatings will provide some protection against smudges - it won't allow all the grease to transfer from you to the screen.
The first oleophobic coating came on the iPhone 3GS.
Oleophobic layers tend to feel slightly slippery, allowing our finger to glide easily across the screen. This is also helpful in terms of scratch resistance - sharp objects will meet less friction and therefore glide along doing less damage.
Sadly, these coatings tend to wear out over time. That's less of a hassle on a smartphone with a 2-year life cycle, but people tend to keep their tablets a while longer. The life of the oleophobic coating also varies from person to person - some of us are a bit more oily than others...
Gorilla Glass comes with an oleophobic coating, as do the more expensive screen protectors.
Checking your screen's grease-resistance
The test is easy - just drop a single blob of water onto the screen. If it stays in a ball shape, your coating is working fine. If it spreads out like melted cheese on a pizza, your coating has worn off.
Caring for an oleophobic screen
Do not use an alcohol-based cleaner (special touchscreen cleaners are available). You could use a water-based solvent. Apply it to a soft, cotton rag (not directly to the screen) and clean it gently.
Glass is smooth.
If your tablet's screen feels rough it is likely for one of these reasons:
* There are lots of scratches
* You have added a polyurethane screen protector
* You have added a plastic screen protector
* A low quality part was used when repairing the screen
* You are imagining it. Seriously. My girlfriend has a plastic screen protector and to me it feels like sandpaper. She thinks I'm a madman - to her it's perfectly smooth. On one forum thread, I found a gentleman complaining that using his screen with his right hand felt rough and harsh, but was perfectly fine in his left hand.
The problem might be the natural oils on your fingers. Clean your tablet's screen, then wash and dry your hands. That will minimise the amount of oil and maximise the apparent smoothness of the touchscreen. Don't use your tablet while eating pizza (who am I kidding? You and me both are never going to stop doing that!)
Personally I don't have a screen protector because the last one I bought ruined the gorgeous tactile responsiveness of the screen. Having said that, I did buy the cheapest possible one. Lesson learned. Next time, I'll pay a bit extra for a top-of-the-line Zagg Invisishield.
Should you get a screen protector? Generally, the answer is yes. It will strengthen your screen. That's pretty much fact. You have to take care when putting it on (many people don't follow instructions and end up with loads of air bubbles) and you might find the screen is less smooth.
Should you get a tempered glass screen protector?
Clear Coat, an American-based company providing screen protection products, created something of a buzz when it announced it would not follow the trend in making tempered glass protectors. Most tempered glass is made in China, which goes against the company's ethos of manufacturing in the US. But more than that, they believe protecting things with glass 'generally doesn't make sense'.
They give the example of 'you wouldn't make a car door out of glass'. Tempered glass is certainly stronger than normal glass, but glass is still relatively weak. [Glass rates a 5 on the Mohs hardness scale, while tempered glass screen protectors are labeled at 9H. Diamond is 10. But wait! That's some clever/deceptive marketing fluff. The 9H ACTUALLY refers to 'pencil hardness' and would actually rate between 5 and 6 on the Mohs scale.]
So why do companies make smartphones and tablets with 'weak' glass screens? Because the user experience is fantastic - not because glass is strong.
In fact, tempered glass is hardened through compression. So when it does fail (the engineer's word for shatter), it fails 'catastophically' - meaning quickly and explosively. Shards of glass will fly out for up to a minute.
This video -
Has no sound, but you can see little bits of glass falling way after the initial impact. Maybe we should all wear goggles when we're using our tablets! Certainly I'm going to stop using mine as part of a Rube Goldberg Machine.
Clear Coat also offer lifetime warranties on all their products - something that would be insane (in their opinion) with a glass screen protector.
On the other hand...
Number of Reported Cases of Tempered Glass Screens Shattering and Blinding Their Owners
So if you want the extra durability of a glass screen protector, go ahead and buy one - just pay a bit more the best quality.
Vibrant Gorilla Glass is a new offer from Corning. It isn't the next generation of Gorilla Glass. It isn't intended to be used as a screen covering. Instead, its intended function is on the backs of smartphones and tablets. Manufacturers will be able to offer customised devices. Imagine a Leicester City-branded smartphone, but with super-high quality, built into the phone itself, and not some cheap knock-off cover.
If you're interested, the best article on the subject is this one.
OGS - One Glass Solution
This is a technique that reduces the thickness of capacitive touch panels by removing the 'air gap' and combining two layers (protective glass and the actual touch screen) into one. There are different ways to do it - the 'sensor on lens' approach or the 'on-cell' solution.
Either way, while it's still a fairly new tecnnique, the advantages are clear - thinner LCD modules; increased efficiency; better optics due to having fewer layers to obstruct light; lower manufacturing costs; better multi-touch gestures.
Hydrophobic Spray/ Superhydrophobic Spray and Coating
These resist water - they're suitable for spraying on a jacket to help keep the water out, or a car. But don't spray them on your tablet.
For all glass lovers out there, there's no better way to spend a day than at the Corning Museum of Glass in New York. Cancel that trip up the Empire State Building - the CMOG has an ATM machine, a cafe, and ample parking.
Gorilla Glass Scratch Remover - Warning
There are some websites recommending '3M 06070 Perfect-It 3000 Trizact Spot Finishing Material' as a solution to scratches on Gorillaglass. While it may have worked in the case of one guy, for others it doesn't remove any scratches and leaves the screen looking duller.
Gorilla Glass 4 gives the best screens on the market today.
Buy a top quality plastic or glass screen protector, never a cheap one.
Buy a privacy protector if needed (they're available in plastic or glass).