Glass Screen Durability Test: A Lesson on the Mohs Hardness Scale

Browsing around the forums I see a few people purchasing screen protectors for their MP3 players that have glass screens. Some might say better safe than sorry but these screens are much more durable than one would think. Below I put a few of these glass screen players though some rather harsh scratch tests, well beyond what the vast majority of users might experience.

screen durability main Glass Screen Durability Test: A Lesson on the Mohs Hardness Scale

The basic reason why one object scratches another object is due to the scientific property know as hardness- intuitively a harder object will scratch a softer object. There are various methods and scales to measure hardness such as the Vickers Hardness Test, the Rockwell Scale, and there is even one recent commercially developed one to measure hardwood flooring.

The one we’ll use here though is the Mohs scale since it’s the easiest one to understand and it doesn’t require expensive specialized testing equipment. You may even remember some of this from elementary or highschool science.

The basic unit of measurement for the Mohs scale is relative hardness. This scale goes from 1 to 10 and is based off of 10 readily available minerals each given a specific number. (wiki)

  • 1- Talc
  • 2- Gypsum
  • 3- Calcite
  • 4- Fluorite
  • 5- Apatite
  • 6- Feldspar
  • 7- Quartz
  • 8- Topaz
  • 9- Corundum
  • 10- Diamond

To figure out where a material fits in on the hardness scale you use these 10 minerals to try to scratch the material being tested. So for instance if you where to test a pure copper penny you will find that Calcite does not scratch the penny but Fluorite will so the pure copper penny will have a relative hardness of around 3.5. Though do realize that this is only relative; Flourite is not twice as hard as Gypsum (it’s actually 7 times harder). The Mohs scale only can state that one material is harder than another- it’s the least scientific but for our purposes it will work just fine.

Heads Up: The videos below contain commentary from myself that may not be 100% scientifically accurate. This article and videos are meant to be a quick and dirty education for the average person. Equate it to Mythbusters, very informative, but could easily picked apart from someone who practices pure science.

The first video I dig into the Samsung P3.

After making the P3 video I realized that the kitchen knife I used was actually hardened or sometimes referred to as carbonized steel, making it harder than the razor blade and harder than typical glass. Regular steel can vary between 4 and 5 on the relative scale and hardened steel is 7 to 8. Glass on the other hand can vastly vary from as low as 5.5 all the way to 7+ all depending on the chemical composition. Like I mention in this next Zune test, this leads me to believe that all of the devices tested have a higher content of harder minerals such as quarts in order to make the glass more scratch resistant.

The last glass composite screen tested is the Cowon S9. There are various types and brands of glass composites, but we do know that the particular brand used on the S9 is made by Corning and is branded Gorilla Glass. There may be other comparable brands of glass on other devices or for all we know Corning makes the glass for other S9 competitors but has not made a press statement like Cowon/Corning did with the S9. Some companies may not want to divulge the materials used for competitive purposes. Though perceptively, I haven’t experienced one brand to be better than the other.

Lastly I wanted to show a hard plastic screen by contrast. This is a rather gratuitous test putting it though the same tests as the glass screen but it’s important to see how the plastic holds up and reacts comparatively. Many times in the MP3 player reviews I talk about how resistant the plastic screen is to scratches. These screens including the one on the Creative Zen X-Fi are among the harder and more resistant plastic screens. You will note in this test the screen on the Zen X-Fi reacts counter intuitively to what we have learned above about hardness. You will notice that steel keys will not scratch the player but the steel razor blade will. Additionally off camera the blunt end of the razor blade will not scratch the screen either. The reason for this has to do with additional hardness properties beyond the simple Mohs scale that have to do with deformation, visco-placticity, and other stuff that goes beyond the scope of this article.

In the end the point this article was to show you that you don’t need to waste your money or trash up your nice device with an ugly plastic screen protector on glass composite screened devices. It also showed that hard plastic does hold up very well to most objects your players’ screen might come in contact with during every day use.

For the younger readers I hope you have been enlightened and can drop some science on your teacher when you get that chapter on the Mohs Hardness scale.


daniel1703 on April 21, 2009 6:10 PM

reminds me of my material science course in Year 1.Cheers, say no to screen protectors.

Zhalfim on April 21, 2009 6:11 PM

this was nicely done, good job grahm!

lawrence on April 21, 2009 6:16 PM

you should have used rocks!Stones always seem to scratch things!

lawrence on April 21, 2009 6:19 PM

And if you say stones normally aren’t in pockets, well some people buy screen protectors in case they drop their players on the street

sumx4182 on April 21, 2009 6:51 PM

I should probably know the answer to this but:Why does my friends Ipod Touch, with a glass screen have a ton of scratches on it when he’s never dropped it? There’s tons of swirls and shit. Wierd…

TedJ on April 21, 2009 7:59 PM

Was I the only person to see the poster image for this article and think “Battery Replacement for Dummies”?

electron on April 21, 2009 9:14 PM

haha… Im cringing… alas, my poor P2 is plastic and is more scratched that you could imagine.. -.- oh well… I will be getting a new one within the year hopefully… :) (nice job Enzo :) )

walker on April 22, 2009 12:06 AM

that was awesome

MMerengue on April 22, 2009 12:30 AM

This page is filled with screen protector advertisements. Oh, the irony.

Joey on April 22, 2009 1:02 AM

Maybe you should have done one of an iPod since I’ve seen a lotin my time and quite a lot of them are scratched. I’d like to see how these screens hold up against iPod ones.

Confispect on April 22, 2009 11:18 AM

This information is great I always wanted to roll over my player with my grandpa’s dumptruck. Hope it can survive.

fox on April 22, 2009 3:49 PM

I know first hand that the ipod nano 1st generation definitely needed a screen protector…but maybe not the new ones out ther e now.

ronin on April 22, 2009 6:31 PM

good work!.. except that my s9 got scratches (though small) from just being in my pocket a few times..screen protector => NOT a waste for me.

Shortly on April 22, 2009 10:15 PM

Graham, it looks like the Kitchen Aid knife is going to draw blood on your right hand!Glad to see this article. I have a screen protector on my O2… Would you recommend that I get rid of it? Won’t it at least provide some layer of protection? I would think that some extra is better than nothing??I’d like to see the O2 tested like this, too. I would imagine it is really susceptible to the razor blade and the carbon steel knife… How about adding one more player to the review?

Mp3 Players on April 23, 2009 12:15 AM

That test was something unthinkable…we think of delicate handling when it comes to advanced gadgets such as these.And it’s amazing to see that it passed the test.

Glymbol on April 23, 2009 5:26 AM

This site is remeber? So there’s no iPod in the test :) .

Chris on April 23, 2009 10:01 AM

This site rocks

Yvonne Carts-Powell on April 23, 2009 9:02 PM

Hi, I’d write a newsletter about displays (see URL). I’d like to link to this story for the next issue (comes out in May).May I include a thumbnail-sized version of your first photo in the newsletter?

Grahm on April 23, 2009 10:25 PM

@yvonneyes you may, thank you for asking =)please email me when its up, i would like to see the newsletter. contact info in the footer.

Andy on April 24, 2009 11:04 AM

The test to the zenxfi almost made my cry… and i also own an ipod touch (my favorite player in my collection due to the amount of extras, certainly not because of it sound quality), and I’ve done similar tests to it, and it remains perfect. That is not the case with the backside… it’ll scratch if you run your fingers against it.

Dan on April 24, 2009 7:29 PM

I dont see how you didnt scratch the S9′s screen, all I did was drop a glass about 2 inches onto it and it took a huge chip out of my screen :[

Aaron on April 25, 2009 2:35 PM

there is this product called applesauce. it got rid of all my scratches

Brett on April 25, 2009 6:59 PM

I realize that I don’t need a screen protector on my Zune to keep the screen from being scratched, but wouldn’t it help (if only marginally) from impact resistance? While glass it hard, it can shatter easier than plastic – I figure a screen protector would help the screen the same way laminated glass is able to stop bullets (i.e. bullet-proof glass). Am I off base on this one?Additionally, for touch screen devices, there are matte screen protectors which help with the fingerprint problem. Just thought I’d throw it out there.

Bo Henriksen on April 27, 2009 5:22 AM

Great test, but I think i would be interesting to see the same test carried out on the Sansa Fuze.I’m the happy new owner of the Fuze, but now, after only a couple of days in use, the device have got the first scratches. A rather negative thing about this otherwise great device!

ramune on April 27, 2009 7:59 PM

with an invisible shield ad at the bottom of the page :p

Scott on April 28, 2009 12:19 AM

I’ve owned a Sandisk Sansa e260 for nearly three years now, and it’s plastic screen has no scratches on it. I keep it in the crappy 50c felt pocket that came as an accessory.On the other hand, my girlfriend’s e260 is covered with scratches. She doesn’t keep it in the crappy 50c felt pocket.It all comes down to how you treat your player.I have one comment to make: Why is there an advertisement for “touchlite for ipod touch” on this page?I thought this was anything BUT ipod!

nithin Thomas on May 11, 2009 5:07 AM

Oh, come on….Its a very simple principle… a substance cannot scratch anything thats harder than itself… Which is why metal can’t scratch glass but diamond can……..I wouldn’t say a screen protector is absolutely unnecessary. Coz, my friend’s ,dare i say it, iPod touch which has a glass screen got scratched when he took it out of his pocket. Apparently there were a few grains of sand in his pocket.Now, he’s regretting the fact that he didn’t use a screen guard.I say a screen guard is necessary….(Forgive me if what i’ve said is already mentioned in the article/videos. I haven’t checked the entire thing out yet)

NWO on May 11, 2009 9:31 AM

My s9 did scratch.. and i hate myself for not buying a shield immediately after i got the s9

NMSX on May 24, 2009 11:52 AM

Hi guys, i want to ask you something…I bought some time ago a creative zen 16 GB, it were a good video player, and still been a good music player, but since the screen was scratched, the video quality was reduced a lot, and are annoying seeing videos with some lines in the screen…The question is, where can i buy a front cover for creative zen??I ask only for the front piece,for the outer part of the MP3 player, the plastic or whatever part… the internal screen are untouched…A image here… a lot, i will wait your help : )Sorry for my craply “engrish” , I’m spanish and im not very good at english xDGreetings, NMSX.

megan on June 3, 2009 9:42 PM

Does anyone know what will remove scratches from a Sandisk Sansa Fuze?

Joshua on June 23, 2009 10:12 PM

alright thanks for the info. now when my friend shows off by scratching his keys against the invisible shield on his ipod touch i can do the same thing on my unprotected zune and show him that he wasted his money, HAHAHA!!!

GMNightmare on June 29, 2009 11:00 PM

Sorry, this is inaccurate. A material that is softer can scratch a harder material.It’s called kinetic energy, E=1/2mv^2. Using kinetic energy, softer metals can indeed scratch harder. Drop those examples from just a small height, and welcome your new scratch.And that’s the whole thing. I, use a whole nice case. It absorbs the damage. My player then stays like new, no scratches. Overtime, those covers and screens will get all scratched up, I simply replace and WHAM, new again.Recently, my new phone has a plastic case that only covers the ends. It’s a few centimeters above the phone… It doesn’t actually cover much so you can still press the buttons and even the screen doesn’t have any. It does the job very well by stopping things from touching the screen, and providing a very functioning buffer.Moral? Don’t be a dimwit and stupid. Buy a cheap cover to protect your expensive purchase.

Scott on July 10, 2009 2:55 AM

Megan, regarding a method for fixing the scratces on your Sansa Fuze, a guy above mentioned a product called applesauce. It looks interesting:

bub on July 31, 2009 7:52 PM

Who take a chef’s knife to there screen dude?

jenghan on August 20, 2009 10:01 PM

Wonder if my K800i create scratches on my Samsung P3…

David on September 9, 2009 8:14 PM

Steel and sand (quartz) are probably the two major concerns.It’s good to know that steel isn’t a problem, but quartz? That is extremely common.It really comes down to your player. Standard window glass is 5.5 on the Mohs scale, while quartz comes in at 7.The S9 is probably safe from nearly everything short of some jewelry, as it is chemically similar to topaz, coming in at around 8 on the Mohs scale.YMMV, I recommend looking into it for specific players.

nsk on September 26, 2009 3:21 AM

so my zune hd does not need a screen protector???

bob on October 28, 2009 12:16 AM

GMNightmare:What you are describing is NOT a scratch. that is a chip.a like comparison to yours would be something like this:Linoleum and Chip-board (what some kitchen floors are made of) can break a glass if dropped on it… but linoleum’s Mohs hardness is lower.. therefore the Mohs scale is wrong…(yes this is a little bit to the extreme, it’s just to clarify the point.)in fact, your point is actually part proof of the Mohs scale.In most cases (no, not all), the Harder something is… the more brittle it is.think about this…if you were to Take a tempered steel rod and a Diamond rod of the same diameter and bend them… the diamond would take more FORCE to break, but would snap (or shatter) before you could even tell it had bent. the steel rod on the other would bend quite a lot before it would break.I know what you are saying (and that’s why some companys decide to use a plastic cover instead of glass). It’s just your comparing impact damage to scratches… it’s like apples to pineapples.-Bob

Ryan on November 11, 2009 1:30 AM

Kitchenaid? Why not use a butter knife, i guarantee my Global Knife will leave a mark on those screens, in fact it might cut the players in half.

Kelly on November 17, 2009 6:17 AM

My Creative Zen was ruined for me by my dog thinking it was a toy and cracked the screen, player still works but I cannot see the menus properly. Nightmare. Would it be worth it to get the screen replaced I wonder? My daughter also has one that got wet in her bag and will not work at all. We are not a lucky family!!

shiny on November 27, 2009 2:47 AM

For those with scratched screens, there is a product available for scratched eyeglasses. It is applied onto very clean glass or plastic and allowed to dry. It will form an optical quality film that fills in the scratches, it is water soluble to an extent, so it is advised to put a plastic film type screen cover over it to avoid having to retreat the screen so often. I have used it on my sansas and it is like night and day. I don’t know the brand I’ve used, its at home and I am traveling for the next few weeks.

jc on December 29, 2009 10:44 PM

The info about steel and glass hardness is not entirely correct. I have scratched a plain glass mirror before scrubbing paint off with an SOS (steel wool) pad, meaning the steel wool was clearly harder than the glass.

Mark Gailmor on January 9, 2010 4:13 AM

This is why I always have used an invisible shield on every device I’ve owned except my first mp3 player, which is an iriver. My two samsung’s had an invisible shield and my mobile phone has a full body invisible shield. While all of these so-called scratch proof devices passed the test shown here all of my friends devices are badly scratched from putting them in their pockets with keys, change etc. My last two devices, including my psp are scratch-free and looked amazing up until they “died”. Go invisible shield. This is the same stuff that they put on the wings of commercial planes folks.

BattleBrat on January 11, 2010 5:35 PM

I use Invisible shields on all my players EXCEPT on the screens, I use Martin fields screen ( protectors on the screens, they are crystal clear and hard as hell. But they don’t bend because they are like paper thin sheets of plexiglass, so I wouldn’t use one on for instance, a blackberry storm. There is another brand I’m looking into Durasec ( I have yet to get my hands on one, I plan on putting one on my Zen X-fi 2

Juste on February 5, 2010 9:36 AM

Hello! i have a ‘silly’ question… I have a Samsung Q2 And i don’t know… should i buy a screen protector, it’s hard to deside becouse i don’t know from what (plastic or glass)screen is made of. Can you help me? (thanks)

Sam on March 4, 2010 3:59 PM

Thanks for the post! You put my mind at ease! Although my Zune HD does have one extremely fine scratch at the top >.>@ JCThe screens on MP3 players (or PMP’s) are made of composite glass which is harder than regular glass.

GG on March 25, 2010 8:57 PM

A friend of mine got fine dirt between the protector and the screen. It ended up sanding down the screen. Once the dirt gets in the sanding mechanism is happening all the time, whereas incidental dirt will be wiped off.

James on March 31, 2010 9:27 AM

im going to admit that was pretty nerve racking to watch.but im really confused as to how i managed to scratch my cowon s9 screen even though i take good care of it.

Jaigoda on May 24, 2010 11:24 AM

The most important thing to note is that while coins and keys and other metal objects won’t scratch a glass screen, sand, dirt, and other minerals often can. If your pockets have a few pieces of sand in them and you put your glass touchscreen player in there, there’s a chance it will get scratched. That’s why if you really want to keep your player looking like new you’ll get a screen protector. However, it’s not all that necessary and you’re definitely not going to be getting scratches just because your keys are in the same pocket as your PMP.

Mennevought on May 29, 2010 12:12 AM

What about walkman x1000?

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