Do you have a question for Touch Guy?

Send him an e-mail at [email protected].

Every phone I have, I drop, and the screen breaks. Why don’t they make plastic touch screens? Sincerely, Tired of breaking my iPhone coverglass.

Yo! I am tired of breaking mine too (thank goodness I have my own touch screen factory to make a new one)

Touch Guy has long said that he believes all projected capacitive (pcap) touch screens below 32 inch will be eventually be all plastic. As you may know from reading these responses, pcap has three major advantages over other touch technologies. 1) 10+ finger multi-touch, 2) provides the best display image, and 3) lasts forever. Well, touch guy has played fast and loose with the last advantage, because, while p-cap will never wear out on its own, the cover glass can, and does, break.

So why haven’t we switched to all plastic touchscreens? Simply put plastic scratches more easily than glass. In choosing whether to have a cover that breaks versus one that scratches, mobile device manufacturers picked the let-it-break route. They know you’re going to buy another phone. Complicating the matter of which material to use is that glass does scratch too, just not as easily. Even the exotic AAS glass (see my white paper) like Gorilla Glass, do not have much improvement over regular glass when it comes to scratches.

Now, getting into the details, there are three relevant measures; hardness, scratch resistance, and taber abrasion. All of these are related. Hardness is generally measured by using Mohs scale of mineral hardness (talc is 1 and diamond is 10), and then the material we are evaluating is compared to a similar material. Some glass is about as hard as quartz, so it has a hardness of about 7. Scratch resistance is measured by using pencils with tips made of increasingly hard materials. The pencils are drawn across the material we are evaluating until a pencil (1-10) scratches the surface, the scratch resistance is given as the number of the last pencil that did not scratch the product. Taber abrasion is a little more qualitative and measures rubbing and erosion of the surface. A taber abrasion tester uses steel wool to rub the surface until a noticeable haze occurs.

About the only transparent surface that will not scratch and is really hard to break is sapphire glass, which is a crystal made of aluminum oxide. Because of its outstanding scratch-resistant properties, you’ll commonly find this glass-like material on bar code scanners and other lenses, as well as high-end watch faces. At one point Apple made a move to “corner the market” in sapphire glass production facilities. The effort was abandoned on the next generation of phones. Now there is so much sapphire production capacity left that you can buy protective cover glass at a small premium over other inferior glass options.

Oh, yeah, we were supposed to be talking about plastic. The Japanese to the rescue! They have invented coatings for plastic that yield glass-like hardness and scratch resistance. Now there is no stopping the plastic juggernaut…except maybe cost. While plastic is easier to fabricate, that is its last cost advantage over glass. Glass is a lot cheaper (made of sand) than plastic (made from petroleum), the coatings (see another white paper on coatings) are very expensive, there can be binding primers which are high ticket items, and then there is the curing process. Oh, and Touch International just spent a bundle for the magic machines to apply these in a super-clean (class 1000) clean room.

So in a nutshell, get ready for your next touch screen to be plastic….

We can bend it, twist it, try to burn it, form it into a dome, dye it, draw on it, and of course…drop it. With plastic pcap, you can keep on touchin’ on.


I currently work in a warehouse where I come in contact with both Resistive and PCAP touch panels. I have heard that touch panels spread a lot of germs because they are used frequently and are not cleaned very often. I was just wondering, what would be the best solution to clean a touch panel? Can I use the same solution for both? Can I damage the screen by cleaning it or mess up the resolution? All I want is to be clean and germ free!

Dear Germaphobe,

First off, everything will be ok! Being exposed to germs can be a good thing for keeping your immune system strong and healthy. With that being said, there are a number of ways to go about cleaning and disinfecting touch panels with very minor, if any repercussions.

Resistive has one of the best reputations for durability and requires very little maintenance to keep in good shape. When building Resistive touch panels, they go through a series of processes, two of which consist of a hot hydrochloric acid bath, followed by a hot lye bath. If the screen is able to withstand opposite ends of the PH balance before it even gets into your hands then you must know it’s resilient.

PCAP is even more durable, thanks to the vast majority built with glass covers.GermaphobeCover glass has countless advantages including clearer resolutions and scratch resistance while matched with an incredible lifespan. Speaking from a chemical stand point, glass is virtually indestructible; there are very little chemicals that would harm the glass that wouldn’t harm a human. So, don’t worry as much about damaging the screen, we built them to be tough!

The most commonly used solution for Resistive and PCAP is just a simple isopropyl alcohol sprayed on a dry or soft cloth. Try to avoid using organic solvents and for dirt or residue use a neutral detergent or ethanol for clearing the touch panel.

A little known fact that might calm your nerves is every person has more germs on them and inside them than cells in the body. So go ahead and disinfect your workspace but don’t feel the need to constantly clean; it may do more harm than good!

Keep Calm and Touch On,
Touch Guy

It’s me PRINCE. I just wanna know the difference between the gorilla glass and soda lime glass. Tell me which one is suitable for touch mobile phone’s smart shield?

Hey Prince:

And I thought everyone in the touch screen business had read my white paper on glass! Let me summarize the salient points, even though none of us are worldly enough to know what a “smart shield” is.

First, if your purpose is to protect the touch screen, glass is a better and more long lasting option than plastic. Touch performance is better through glass, and its non-scratch characteristics exceed all but the most exotic (read expensive) plastics….it is also clearer and thus easier to read information on the display.

But you are asking Touch Guy to enter the battle of which is best…Gorilla (Corning’s trade name for AAS glass [read the white paper]) or soda-lime glass in this application. In the beginning, shattered-glass-there were a lot of problems with the touch panels breaking when the smart phone was dropped (good business for Touch Guy), so the top layer, called cover glass or cover lens, was chemically strengthened, which helped reduce breaking. Chemically strengthened glass is made by exchanging sodium ions for potassium ions, the latter being bigger. After this process the top surface is compressed and the glass under surface remains under tension, which makes the glass much more difficult to break. Gorilla glass and plain-old-soda lime glass have pretty much the same break resistance after the chemically strengthening process.

However, AAS glass is more porous, so when it is chemically strengthened, the potassium ions go deeper into the surface of the glass. If your habit is to put your smartphone in your pocket with your keys and spare change, and if your active life-style causes the keys to scratch the glass, the surface compression ions will be compromised first in soda lime because they are not as deep.

The person with the pocketful of keys and smartphones will need a lot more 10,000-step-days before his Gorilla cover glass will break when dropped (her smart phone is probably not in her pocket, so you may need a “his” and “her” version of whatever smart shield is).

Now, in the more than you wanted to know about the matter category…all glass is vulnerable to cracking when it gets hit on the edge…and the most vulnerable is glass that is not seamed (smooth edge) before it is chemically strengthened. In the purely rumor category, the iPhone 5 was the first to use Gorilla glass, and initial comments were that it was breaking more than the-plain-old-soda-lime touch panels. The purely rumor explanation was that the initial phone design had more access to the edge of the cover glass, so it was easier to whack and therefore break….welcome the law of unintended consequences. So you will want to step in your smart shield a little to protect its edge.

So there you have it. Quite possibly, after all that you may have still not got the answer you were looking for even though I hope you learned something. I can definitely appreciate the repair market for smartphones. Of course, Touch Guy’s new all plastic molded touch screens will not break or scratch – so perhaps many devices will not need this “smart shield” in the future.

Keep Calm and Touch On,
Touch Guy.