Gorilla Glass 5 and Shattered Expectations: Revisiting Old Solutions to Current Problems
Update: There was an issue with JerryRigEverything’s initial scratch test which has since been corrected. The Note 7 is scratching at a Mohs of 6 like Corning stated, however that still is lower than the Mohs hardness of 7 that is recommended for watches and jewelry, meaning that the point of this article still stands.
The recent scratch tests of the Samsung Galaxy Note 7 have brought back into the limelight a rough truth; scratch resistance and drop resistance are often two opposing traits. The better the scratch resistance, the easier it is for the material to shatter.
As you go down the Mohs scale, materials become progressively softer and more malleable, and as a result are able to flex further without breaking, but this also makes it easier to scratch them. On the other hand, as you go higher up the Mohs scale, they become harder and more brittle, allowing them to resist scratches, but causing them to shatter instead of bending.
While Corning is doing everything they can to improve the performance of their Gorilla Glass, they are in essence playing a giant balancing act, trying to find how much they can improve their shatter-proofing, without losing too much scratch resistance. We might be asking too much of them. In fact, it may not be possible at all for them to give us what we’re looking for with one single or traditional material.
Corning was very clear in their response to Zack’s scratch test video that glass should be somewhere between a 5 and a 6 on the Mohs scale. Unfortunately, that’s just not quite good enough. Jewelry is often recommended to use stones with a Mohs hardness of 7 or higher, because anything less than that will be scratched up by dust. The sand that makes up a substantial portion of household dust is quartz, with a Mohs hardness of 7, which will certainly scratch anything with a Mohs hardness of 6 or less. This means that any jewelry with a Mohs hardness of less than 7 will lose its shine quickly and become scratched, even just from cleaning it, and that applies equally to screen protectors and the screens themselves. Now, a 5 or a 6 is great for protecting against soft metals like what you’ll find in keys, which range between a Mohs hardness of 2.5 to 4, but isn’t going to do anything against sand or dust, let alone something like a diamond ring or other jewelry.
“With its shatterproof protection, the Moto X Force raised the question, “why does it have to be one layer?””
By adding more glass, in places where there used to be metal or plastic, we’re reducing the chances that a phone will hit its frame when dropped, and increasing the risks of it striking glass (and potentially shattering).
Corning has risen to the occasion by improving their drop resistance for both Gorilla Glass 4 and Gorilla Glass 5, but it has definitely come at a cost in terms of scratch resistance. We were already seeing reports of the Samsung Galaxy S7 scratching relatively easily (sadly, my S7 was scratched more at the end of my first day of use than any phone I have had prior or since), and from what we’ve seen so far, it’s only gotten worse with the Note 7.
We don’t need to be trying to force one material to do both. All we’re doing is making trade-offs and trying to find an acceptable balance.
Motorola had an interesting idea recently, although their implementation could still use some work. Their idea essentially boiled down to; “Why does it have to be one layer?” With the Droid Turbo 2 (also known as the Moto X Force) and the Moto Z Force, they unveiled a 5-layer screen. An Aluminium chassis, the AMOLED display, two digitizers (so that if one breaks when dropped, the touchscreen will continue to work), a pane with a low Mohs hardness to protect against shattering, and an exterior pane that is designed to be replaceable, and which is supposed to protect the internal layer from scratches.
Unfortunately, in their attempt to make the exterior layer as cheap to replace as possible, they used plastic, like many basic screen protectors have, which scratches at a Mohs hardness of just 3 (or around a 2H on the Pencil Hardness scale that screen protectors are often measured with).
But what if they hadn’t? What if instead they used a tempered glass (or even a future version of Gorilla Glass) screen protector. Yes, it would bump the replacement costs of the screen protector up slightly, but it would also drastically reduce how often it would need to be replaced, and would do a much better job of protecting the screen. And yes, the external layer would be more likely to shatter than the one they’re currently using, but that’s the job of the internal layer (which is bonded to the display assembly). The external layer is there to protect against scratches, not drops. It’s the same reason many of the best phone cases have two layers, a soft internal layer to protect against drops, and a hard external shell to spread the shock and protect against scratches.
Millions of users already opt for screen protectors — Why not make it a feature, and work to minimize the trade-offs?
Despite their wide availability and consumption, people typically aren’t huge fans of screen protectors due to difficulties with placing them correctly, trouble finding them in the right size, how they look sitting on top of the glass, some issues with reaching the edges of the screen with certain screen protectors on, and difficulties they can cause with certain phone cases. If the issues with finding the right one and fitting it properly weren’t enough, then you also have the rainbowing and possible touch input issues that we often see as well. All of these issues are sacrifices that millions of consumers trade for the security of a more-protected device. Thankfully, a phone designed to have a screen protector can help mitigate many of these issues. Motorola’s “shatterproof” phones have a raised lip around the outside edge (so that the screen protector will sit flush with the face of the display), and have raised speakers to help guide the placement of the protector. More importantly, cases are designed with the screen protector in mind, instead of it just being an afterthought.
Now, this idea isn’t without its own drawbacks. Having an extra layer makes the phone slightly thicker and it can result in slightly worse performance in daylight due to the gap between the layers. Many people will not realize that there is a second layer, and as a result won’t think about replacing the scratch protection layer if it shatters — informing customers is thus key. Also, if you make the top layer as scratch resistant as possible, then it will shatter if you drop it. It will shatter more easily than any other phone on the market. But the layer that is actually fused to the display won’t. The shatter resistant layer will survive, and then it’s just a matter of replacing what is essentially a screen protector.
Maybe what we need isn’t glass construction. Maybe what we need is a return to phone bodies made of metal and premium plastics, with a bit more foresight about screen protectors.
The backs of our phones don’t need to prevent every little scratch, they just need to survive when we accidentally drop them. A scratch on the back of our phone, while annoying, doesn’t do much to harm our actual user experience. On the other hand, a scratch or crack on the screen can have major negative effects on usability. Different materials work better for different needs, and we should be making the most of them. We don’t need to have just one material. OEMs can use as many as we want, they can use the best materials for drop protection for the backs of our phones. They can make sure that the pane of glass fused to the digitizer won’t shatter. Proper scratch protection can be built in, with phones designed to accommodate screen protectors better than before. We have a wide selection of materials available that are suited for different uses and we can use more than one material for our phones’ fronts, they don’t have to be just glass. They can be a mix of materials, as the Moto X Force proved. In times like this, maybe that’s an idea worth revisiting.
Do you use screen protectors on your devices? Do you worry about the scratches from daily life? Let us know!