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.
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.