PET, TPU, or Tempered Glass – all you need to know to choose a screen protector

A bit of a disappointment in the past, today's screen protectors are easier to install, cheaper, and better than ever in every aspect. There are three varieties — PET film, TPU (polyurethane), and our undisputed favorite — tempered glass. And then there are two methods to get them on your display — dry and wet. So here's more about how screen protectors work and what they offer.

PET Film screen protectors

Obviously, PET doesn't stand for a dog or a cat. It means "polyethylene terephthalate" — a type of plastic that's available in many variations depending on specific applications. In the manufacturing industry, it's used for mundane stuff like liquid and food containers. But this doesn't mean that PET film protectors are glorified water bottle plastic. They consist of polyester film with a scratch resistant matte coating on one side and a silicone adhesive on the other. 

Quality ones are quite clear and add a functional anti-scratch layer to your screen, but have no impact protection. Their scratch-resistance isn't as good as that of the latest Gorilla Glass implementations but will they'll take the hit in case something abrasive gets in contact with your screen. 

They are cheap, and usually come in packs of three or more. Their downside is that plastic is the easiest to discolor from sun rays and oil buildup from your fingers, and it doesn't feel as nice as glass does to the touch.

If you have a cheaper or older phone, or you're fine with the most basic and affordable screen protection, get a PET protector. The manufacturer doesn't really matter, but if you have a soft spot for a particular brand, there's no reason not to go with theirs. Chances are that protectors from established brands will be better cut-out for your device and won't leave loose edges that can catch on to your clothes and peel the protector away (it has happened before).

TPU screen protectors

TPU (thermoplastic polyreuthane) is next in the screen protector food chain. This is chemically-enhanced plastic whose properties include scratch resistance, elasticity, oil and grease resistance, and increased toughness. Since the material is elastic, it has limited "self-healing" abilities. This means that its slight softness gives it the power to absorb non-extreme impact, such as most drops and lighter scratches, while retaining all or most of its original composition. For example, lighter scratches usually leave just a small dent in the soft plastic, which slowly returns to normal.

The "military-grade" tag most TPU protectors proudly carry is worthy of an explanation. One manufacturer says that this material is used "to protect jetfighters". And what do you know, it's true! Skim through this Aerospace Surface Protection brochure — it's full of polyurethane protective tapes used for "aircraft and windmill leading edge protection". However, getting a TPU case or screen protector doesn't guarantee it's made of the same quality of material. But your smartphone also isn't a fighter jet, right?

If you are willing to pay a slightly higher price, a TPU protector is, logically, better choice than PET film. At the very least, it's going to provide better impact protection (although you shouldn't be pushing your chances). It's also nicer to the touch, although it isn't glass-smooth. Arguably, the best part is that you'll get to explain to your friends and acquaintances how your phone has "fighter jet protection". Pretty cool, huh?

Tempered glass screen protectors

Protection with a temper! Tempered glass (TG) screen protectors are the absolute best you can buy. Material-wise, a high-quality TG protector is multi-layered, usually starting with shock absorbent silicon on the bottom layer, followed by PET film, and an optically clear adhesive to 'sandwich' the previous two layers with the next two, which are tempered glass and oleophobic coating. 

All of this scratch, oil, and shock protecting goodness is compressed into a <0.4mm-thick sheet that's no harder to apply than a PET or TPU protector, and none heavier or otherwise obnoxious.

A glass protector is superior to its alternatives in every way. It has better light transmittance, making for a clearer display. It's anti-reflective and glare reducing. It has oleophobic coating, which heavily reduces fingerprints. It has the smooth feel of actual glass under your fingertips. It can even resists sand scratches, making it the only viable option for beach-goers. 

And let's talk about shock protection. T-glass protectors boast a material hardness rating of 8H to 9H, meaning they are hard enough to resist scratches from anything that's not topaz or corundum (extremely hard aluminum oxide). Yet, they aren't completely shatter-proof. 

Since this is toughened glass we're talking about, in the event of a fatal drop, the protector will absorb all the damage and break into tiny shards. Chances are pretty good that your display will end up unscathed underneath. Thus, instead of having to replace the entire screen, you'll only have to get a new protector. Which is easier on both your soul and your wallet.

As you probably expected, tempered glass protectors are the most expensive kind. Still, thanks to their popularity and fierce competition among manufacturers, the prices have come down drastically. 

Dry vs wet screen protector installation

There are two methods for installing a screen protector - dry and wet. The method is usually specified on the box. Installing a screen protector can be a tedious and finicky job and many people are hesitant to do it, some even opting to pay a "specialist" to install one for them. In reality, protector manufacturers know that and every reputable brand goes to great lengths to provide all the necessary tools and instructions so anyone can do it.

Dry installation

The dry method keeps the protector glued to the screen with static electricity. There's no adhesive involved, and the application is very straightforward. The exact steps will be explained on the packaging, but here's a rundown with a few tips.

Wet installation

Wet installation might sound scary but in practice it's not much more difficult than the dry one. The process is very similar to the one described above. 

However, before putting the protector to the display, you first need to apply some liquid adhesive to it. There are different ways to do that depending on what brand you've chosen. 

Some provide tiny spray bottles with the solution inside. You spray the display or the protector (or both, it varies) and then have to adjust the protector by slightly moving it around until you're happy with the fit. After that, you use the provided squeegee to remove any bubbles and excess liquid between the display and the protector. A final wipe on the top should leave you with a nice, clean look.

Other brands provide a better method for application but it will cost a bit extra. With the protector comes a special contraption that holds your phone. It not only helps spread the liquid evenly, but also makes sure the protector is aligned and applied perfectly with almost no effort on your part.

And then there are companies that sell wet-mount protectors using adhesives that require UV-light curing. Of course, they come with the UV light in the box, but the price for one can be quite high (still cheaper than a new display, though).

Fingerprint sensors tucked under the display are now commonplace but with the futuristic technology that powers them came a problem. Screen protectors add a variable to the fingerprint-scanning process which the phones sometimes can't account for. This can result in either a worse chance of getting a correct read or a complete lack of compatibility between some sensors and protectors. 

Even worse, a screen protector can compromise the security of your phone. The ultrasonic fingerprint reader of the Samsung Galaxy S10 had issues with some protectors, allowing devices to be unlocked with unregistered fingers. While that issue has been fixed, it's best to make sure which protectors are recommended(or supported) by the manufacturer of your smartphone.

A common question coming from people that obviously aren't using screen protectors is if applying one can hide existing display scratches. And the answer is: it depends. Shocking, right?

First, it depends on the severity of the scratches. Obviously, the deeper the scratch the smaller the chance it will disappear under the protector. But mostly, it depends on what protector you're applying. If hiding scratches is your goal, your best bet is a protector with liquid adhesive. The liquid will fill the minuscule void left by the scratch and once the protector is on, it could disappear completely. 

For very tiny scratches, even a regular dry-mount protector could be good enough to mask them.

Wrap-up

With so many options available, and at very fair prices, getting a screen protector for your device has become a no-brainer. PET film products are the best choice for basic screen protection. TPU protectors can be a bit rare, but they have the best ratio of affordability and toughness. 

Finally, Tempered Glass protectors offer the ultimate in protection and feel, but they are the priciest of the bunch. Still, even the most expensive ones make sense for flagship smartphones and tablets. Unlike cases, they do little to change the appearance of your expensive device but can save you hundreds of dollars.