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Tempered glass screen protectors - understand and beware! Answered

I recently had the joy of needing a new screen protector for my mobile after being dumb enough to drop it on gravel.
The hard cover took all the impact but the film protector on the screen was scratched badly.
Was old and partially worn anyway so I decided to upgrade to a Tempered Glass screen protector.
Being somewhere rural I had no chance to get one in a shop so I ordered online.
With no intention of advertising for some sellers, I collected a few links so you can check what I am talking about:

So, what is my concern with these? They all can be found on amazon and other online services as well as on local markets...
As I said I ordered a glass screen protector.
If you check these listings and even some of the packing you will notice they all have a thing in common - being shatter proof and of 9H hardness.
I also love this video showing how to remove and fix a glass screen protector!
The last time I checked glass had one very distinct feature: It is hard and before it really bends it breaks - unless you use fibre optics of fibre glass cloth...

What is my concern and warning here?
Pretty simple: Stay away from expensive scams!
Some claim their screen protector is only 0.25mm thick, even the 0.2mm one I measured was over 0.5mm with the glue...
The hardness of 9H refers to the so called Moh's hardness - look it up on Wikipedia if you like.
That means these tempered glass protectors would have a similr hardness than a diamond, or at least close to it.
Problem is that they are made from plastic to start with and not glass at all.
They claims that the screen protector is flexible because it is so thin - again a fake!
Even the thinnest tempered glass will shatter if you bend it enough, not so these plastic ones.
If you think I am making all this up try to use a really sharp knife or deburring tool and cut the thin sides of one of these protectors.
All the ones I tested could be cut quite easy - and I though glass can't be cut with a kinfe...
A nice website showing that the scratch resistance is far from the claims can be found here.
And a video showing how a real glass screen protector sounds and breaks can be found here.

So is it really all bad and should I avoid getting one?
Not really if it is only for the added protection.
To be clear here, and without the intention to blame any of the above sellers, some protectors actually do have a top layer made from glass and you can hear it as in the above video - it sound solid and not like plastic if you tap it with something hard.
Another factor is the simple fact that plastic absorbs impact much better than glass.
So where a real glass screen protector might shatter and crack like in the above video, the fake ones might one get a nasty dint or scratch.
But you should be aware and clear about what you get and what to expect from it.
These glass imitations are made from a strong polycarbonate plastic, similar to the stuff used for bullet and explosion proof "glas" windows - if you every watched the Mythbusters you have seen the big sheets I mean.
The top layer of these things is specially treated to repell water, oil and dirt, it also gives the surface the good scratch resistance.
The technique is nothing new, camera lenses, plastic sheets and the clear covers you see over the timetable at your bus stop all use it.
The new thing is to intentionally mislable a product to make the consumer think it is glass ;)

What is the real difference for the user?
Check this video.
Here a guy performs a drop test with a real glass screen protector.
Thing is once the protector breaks the screen itself is broken too but until then it was not too bad.
Here it is demonstrated how a real glass screen protector reacts to certain types of abuse - one of the reason I decided on glass.
Compared to the plastic counterfeits just the sound on the glass is worth it, but I think the hacksaw was best.
Another video from XDA gives a bit more info on how the glass is made - if you can't seeing a phone being abused then don't watch the drop tests at the end ;)
Glass with these hardness levels and types of surface protection will give the user a long and worry free use of the phone.
The plastic fakes will perform at a similar level for some time but will show signs of wear long before even the top coat of the glass one fails.
Both types have their uses and if the fakes would be labeled correctly the user would actually benefit from that.
On bigger screens like a tablet I would actually prefer the plastic ones to prevent damage once it needs replacing.
On a mobile used in less than perfect conditions I would also go for plastic as it usually is a bit thinner and will fit better within quality hard covers.
But when it comes to real abuse like using with dirty fingers most of the time or mostly outdoors where a lot of dust and fine sand can be involved I always go for glass.
If you paid attention to the surface treatment then you already realised that the plastic and the glass are in the same region, making them quite scratch resistant.
Still fine sand or metal dust will scratch it....
The difference is in the hardness of the actual material that was covered with the oleophobic film.
Glass will not give in any way, where plastic is much softer - so not to be confused with the surface hardness!
This mean that sharp and point object will easier penetrate the plastic than the glass, something to be considered if you often ecounter harsh use.
In terms of actual protection we need to differenciate between surface quality and actual screen damage.
After all when badly scratched we can replace the protector but if the display got damaged we are back to square one.
The surface hardness was already covered so let's move on to the screen itself.
In some of the above videos you can see the abuse a screen might see in normal conditions, and if we would not drop our phones so often repair shops would not be at every corner LOL
I have done quite a few screen repairs, mostly for friends and work mates that did not want to pay the hefty extras in a repair shop.
From there I got the stories on how it happened and in almost all cases the screen cracked when the phone landed on the corners.
In one case the screen and glass protector failed, including the actual display when the phone was dropped out of a 4WD and landed screen first onto a rock.
A glass protector will spread the (direct onto the face) impact force onto a much larger area, where a plastic one will produce a dint onto the actual screen much sooner.
So again glass wins in terms of actually protecting your expensive screen.
But be aware that all this is useless if the phone lands on the corners!!
Let me explain:
Both the top glass on your screen and the screen protector have a thin layer of "glue".
This acts like a shock absorber, so unless an impact goes deep enough so the pressure on the actual screen is too much only the protector should fail.
But the screen itself is a tight fit into the frame of the phone, so all side and corner impacts go directly into the glass.
As the rest of the glass has no way to give or go the stresses will crack the screen.

How should I treat my phone with the new screen protector?
Exactly the same way you would without it of course.
But if you don't have a proper cover that offers protection of the corners you should invest in one.
Having a quality protector and a good case does not mean your phone can be used as a football, see it as an added insurance in case something does go wrong.
For obvious reason it can also pay off to have a spare at hand, if something bad happens that requires replacement of the protector you won't be left with an unprotected screen ;)
Last but not least, double it up:
For people that already know their screen will see a fair bit of abuse in term of scratches it is a good idea to put an extra film protector onto the glass one.
Once it is too scratched you peel it off and replace it, while the glass protector gives you the actual protection for your screen.

Corning Willow glass
As time of wrinting Corning Willow glass is the only "flexible" glass on the market, unless stated with your flexible screen protector you can assume it will be just plastic.
I did not list it above as this high tech material is mainly reserved for displays and at least to my knowledge is not available for screen protectors, although I will stand corrected as I have to assume some big players use it for their protectors.
The material is actually a sandwich where an ultra thin sheet of glass stis bewteen two layers of durable coating, read it up on their website it is quite interesting.
It won't reach the strength of their famous Gorilla glass so without an outer plastic that has the additional oleophobic coating it won't provide the strenght of real tempered glass protectors.
Some phones like the Galaxy Round and the fleixble HTC phones use it for example.


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1 year ago

I bought a panzer glass for my new phone Huawei p20 lite, and after three days my panzer glass started cracking and it is still continuing


1 year ago

Hi, I was reading this article because for some reason my last tempered glass protectors quality is poor as minimum. My actual phone is now around one year and a half old and I have already had to change the tempered glass once, and it is again in a very poor condition. Some good day a crack just showed up and the fake cristal is just starting to peel, it is already making top left icons hard to see. My previous phone had a protective tempered glass protector for its two whole years of life and never had a scratch, but the ones for the new just cracked in the pocket and look like having survived a car crash or something. I'm a bit pissed off with this so I want to know if there's a way to know if the protectors are good quality ones or this self-detructive trash.


Reply 1 year ago

That's weird. I buy the cheapest ones I can find on eBay, but I do replace them every several (many) months. But I use my phone a lot. I've never had any serious issues but the thin glass does crack fairly easily...


1 year ago

Some good information, though it appears to be more of your opinion versus factual. Please spellcheck your article(s) before you post. Find it hard to really believe the information with typos.


Reply 1 year ago

So you registered just to post a reply on a 2 year old topic?
Not only did things change a bit since then but:
If you find a typo in my text then you can use it freely and to your liking.
But if you use my typos o make money I would like to see a small percentage from the earnings ;)


2 years ago

I so value the few thinking, independent,and explorative persons who take the time to further educate themselves and others in this manner.Thank you


3 years ago

Hey I work for an electronics company that makes screen protectors. The Moh's hardness scale does not apply to 9H hardness although many sites online are claiming this. It's actually referring to the strength of a "pencil test." The scale of at what pressure will a pencil scratch the surface. Its extremely misleading, just wanted you to know that even if the companies are blowing the quality out of proportion, they don't really mean it's almost as hard as a diamond. peace.


Reply 3 years ago

Well, it still comes down to misleading info from the manufacturer.
They are all happy to put 9H and other claims directly on the packing without specifying that they use a "fake" test that happens to use the same values as standardised test.
I do admit the quality over the past few years has greatly improved but the facts still stand.
If you use words for product features that will make everyone think it is far superior without specifying that your words have no meaning than it is misleading advertising ;)
There is a reason why noone clearly states: We use our own tests with a pencil and do not conform to the standard ROHS hardness test.
So peace once the manufactures claims actually meet the reality without trying to fool the customer ;)


Reply 3 years ago

I absolutely agree haha, its a typical sales move like most cheap China stuff out there. Also, they're not fully tempered glass, they're mixed with a cheap plastic or else it wouldn't bend like it does. Good post though, people need to be more educated on the products they buy without reading into the hype.


4 years ago


I saw the things you point out on ebay with hammer and all on the pictures, I laughed at it but thanks for the detailled article you made about that, very interesting to read (I don't have a phone that needs one but still)