[Asus ZenFone 3 Accessories] shade0723:
Ok so you bought a zenfone 3. Beautiful little piece of hardware isn't it ? The glass and metal design looks premium alright but it would be a pity if you got the screen all scratched or shattered. Remember that gorilla glass 3 is scratch resistant not scratch proof and it can be scratched quite easily by dust particles and sand. Also it can be easily shattered like any glass. Only sapphire glass can be called scratch proof but you won't see sapphire glass mass produced for smartphones screens any time soon because it's too expensive and very difficult to produce for larger surfaces.

So the best way to protect your precious screen is by applying a sheet of tempered glass. It has a higher scratch resistance than gorilla glass and it is designed to shatter on impact to dissipate the shock energy that would otherwise destroy the screen glass. It is very easy to apply on smartphones with flat screen surface but there's a catch. There is a new design that's being implemented on smartphones screens for a while now with curved margins and all which is generically called 2.5d glass. Zenfone 3 features such a screen. So what's the problem you may ask ?

Well long story short this means you can't apply a flat tempered glass on a screen with rounded margins without the manufacturer being forced to reduce its dimensions to only cover the flat surface, unless you can find a manufacturer that produces tempered glass with curved margins. So far I could only find such screen protectors for the Galaxy Edge series. They are nowhere to be found for our beloved asus zenfone 3 for example.

So yeah there are plenty of flat screen protectors for the zenfone 3. I myself got one from Nillkin. It is carefully dimensioned to only cover the lcd on the left and right margins. Problem is that the curvature of the screen starts somewhere from 1-2mm from the inner side of the lcd depending on the manufacturing tolerances. This means that even if you perfectly position the tempered glass there will still be 1-2mm on the margins that will hang in midair because it can't stick to the curvature. From what I could find this issue is commonly referred to as the "halo effect". And it's ugly as f*ck.

So there's good news and bad news. Good news is that I've found a way to properly apply the tempered glass even on the margins. Bad news is that you need some tools you won't find in the original package, namely a VISE (yes, that thing on the WinZIP icon) and SILICONE OIL or VASELINE (both have to be perfectly clear with absolutely no colour and make sure they don't change colour in time).

I only did this once with a Nillkin tempered glass for my ze520kl but it should work for any curved screen.

Ready ? Ok so go ahead and perform the steps as indicated on the original packaging (clean the screen with the alcohol wipe, dry the screen with the dry wipe, dedust the screen with the anti-static sticker, perfectly align the screen protector and apply it). Obviously it won't stick to the margins so here comes the hard part.

This is going to take a lot of patience but not much effort. The key to sticking to the margins is a lot of constant pressure and if that fails this is where the silicone oil comes in handy to fill the gap between the screen and screen protector.

So this is what I did to get a perfectly applied tempered glass on my zenfone 3.

-First I tried to fill the gap on the margins with a drop of silicon oil and then I applied pressure on the margin intermittently with my thumb to help the silicon oil to get inside the gap easier then I wiped the excess. The purpose of the silicone oil is to create a clear visco-elastic medium, a bridge if you like, for the light to travel between the screen and the screen protector without changing path (without too much refraction). Problem is that it can't fill the whole void and you still get a bit of halo here and there as there is still some air trapped within the adhesive.

-This is the part where the vise comes in handy. I strongly recommend you use a vise with rubber protection on the jaws (or whatever they're called). You could in theory do this with your thumbs but it is very hard and tiring and you can't apply constant pressure for a long time.

So I fitted a margin of the screen in the vise and tightened the jaws hardly enough to forcefully compress the adhesive and remove the air bubbles trapped inside but soft enough not to actually crack or damage the touchscreen. Then I left it in there for about 1 hour on each of the 4 sides. If there was still some air trapped in the adhesive I would apply some pressure with my thumb to stir it a little and then I put it back in the vise and leave it for a while longer until there would be no air left.

After 4-5 hours I got a perfectly applied screen protector on my zenfone 3 with no halo effect on the margins.

Since I've never done this before I have no idea how long this will last and if the problem will ever occur again. But if it does then all you need to do is just apply some more silicon oil periodically and you're done. There won't be the need for the vise anymore.

Good luck and I hope this bit of information will help someone in the long run to develop and perfect the method. I doubt the average user has a vise installed on his/her desk so this tutorial is mostly intended for the more savvy people. Don't blame me if it doesn't work for you or if you damaged your phone.

Also, I suspect that on various models of smartphones there won't be the need for the silicone oil and all you need is just some good constant pressure.