When smartphones have just emerged, grease or fingerprints would inevitably be left on the screen when fingers touch the phone. Now, if you buy a new phone, your touch feeling on the screen may become smoother, and it’s not easy to leave fingerprints. In fact, this is because the glass is treated with an oleophobic coating. The same is true for the mobile phone screen protector, especially the tempered glass film. The oleophobic coating on the screen or tempered glass repels water and oil, these hydrophobic (water-repelling) and oleophobic (oil-repelling) coatings are often called “self-cleaning” coatings because of how they shed water droplets and resist greasy fingerprints, meanwhile, it brings users a great touch experience.
However, people who are experienced in playing mobile phones should have found a phenomenon: Touch feeling might be different in different mobile phones, There is different touch feeling in different mobile phones, some feel very smooth while sliding across on screen, no fingerprints left on the screen, while the others tend to hang around longer. In fact, the difference feel is most probably caused by oleophobic coating. Although the basic function of the tempered glass film or screen glass is to prevent scratches, the touch feeling of a tempered glass film or screen is also important for the user, the effect of touch experience is actually decided by oleophobic coating, this is another factor to measure how the quality of a tempered glass screen protector is.
What is the hydrophobic and oleophobic coating on the screen protectors or glass?
The oleophobic coating is usually called “hydrophobic coating”, “lipophobic coating“, “anti-fingerprint coating” or “AF coating”, it is precisely because of the hydrophobic and oleophobic characteristics that repel water or oil, instead, it gives the user a smooth hand feel.
The oleophobic coating is a thin glaze of the fluorine-containing composite coating prepared from a fluorosilicone resin with a special structure. The oleophobic coating is water repellant, oil-proof, stain-proof, moisture-proof, insulation, acid resistance, anti-fingerprint, abrasion resistance, scratch resistance, adhesion as well as light transmittance. It is easy to clean and take care of. It is mainly used in the protection glass of high-end digital products such as mobile phones, cameras, touch computers, TVs, as well as the water-proof, anti-fouling, and anti-fingerprint treatment of high-end products such as ceramic sanitary ware and hardware sanitary ware.
How does oleophobic coating work?
Many people might know the self-cleaning properties of lotus leaf, dirt particles are picked up by water droplets due to the micro and nanoscopic architecture on the surface of lotus leaf, which minimizes the droplet’s adhesion to that surface. The oleophobic coating is the bionic representative of the lotus leaf effect.
Specifically, the oleophobic coating makes water with ultra-high surface tension (shown as water repellency), gathers the surrounding liquid to form water droplets with a higher water contact angle, and makes the oil shrink into small oil that is difficult to adhere to the surface. Even if there is a small amount of residual oil, it can be easily wiped off with a towel or paper towel.
The function of oleophobic coating on glass or screen protector
Oleophobic coating is an industrial coating. Nowadays, mobile phone screens or tempered films are treated with such a thin glaze of anti-fingerprint treatment before leaving the factory. Oleophobic coating is applied to the surface of the mobile phone display glass or tempered film through various processes. The function is to increase the hydrophobicity, oil drainage, and anti-fouling properties of the screen or tempered film and increase the touch’s smoothness, thereby improving the user’s touch experience.
The most important role of a screen glass or tempered film in adding oleophobic coating is that it is not easy to leave fingerprints, and it is more convenient to clean the glass. Since fingers tend to have grease and sweat, by contacting the screen, the fingerprints and grease will be left on the screen, which affects the beauty of the screen. The oleophobic coating makes users touch or operate more smoothly on mobile phones, improves touch experience, especially those who are fanatic enthusiasts of mobile phone games.
Manufacturing process of oleophobic coating
There are different spraying processes of oleophobic coating on screen glass or tempered glass film, different wear-resistant effects will be lead to by using different processes, thereby affecting the quality of tempered glass.
In the current market, the spraying process is available in manual spraying, machine spray, plasma spray, or vacuum metalizing.
The manual spray is to manually brush or spray the oleophobic coating on the screen or film. This method is poor and out of date, one reason is that it cannot be applied evenly, the other is that the oleophobic coating is unable to firmly adhere to the screen or film. It will be easily worn off as short as a few hours or a few days. It is a waste of money if the manufacturer tells you the oleophobic coating is treated with manual spray.
Replacing with manual spraying, oleophobic coating treated by machine is more evenly, but it is not durable either, some very cheap films are treated by machine.
The plasma coating process involves spraying a substrate with molten or semi-molten material to create a hard coating that protects against oxidation and corrosion wear caused by environmental and operating conditions.
Plasma coating is applied using a plasma arc to clean the glass before spraying the oleophobic coating to change the surface characteristics of the glass. With chemical treatment protect from smudge, water, and fingerprint. It can completely go deep into glass pores to offer excellent stain resistance. Plasma coatings are dense and strong, making them a favorable option for glass protection and refinishing. It has become the mainstream spraying method for oleophobic coatings on many 2.5 or 3D tempered glass films.
Vacuum metalizing / Vacuum deposition
Vacuum metalizing is applied by putting the glass and oleophobic coating in a vacuum environment. The sprayed oleophobic coating will be closely integrated with the glass in a high-temperature vacuum environment. This kind of coating is not only more evenly, high-density, but also very strong. Smartphone screens are usually coated with an oleophobic layer in this way.
How to check the quality of the oleophobic coating
The oleophobic coating affects not only how your smartphone looks but also how it feels. oleophobic coating with good quality makes your fingers easily glide across the screen at ease and there’s very minimal friction to slow you down. It is also extremely easy to wipe off fingerprints and grease on your mobile phones.
As regular users, it is relatively hard to judge how good the oleophobic coating is in a professional way. The simplest way is to drip a water drop on the tempered film/display, by observing the water droplets and the contact angle of the screen, generally say, as long as dripping water becomes a droplet (simply check if the droplet on the surface of the screen is round), the contact angle of the droplet and the screen is greater than 90 degrees, it indicates that oleophobic coating is effective.
When you need to detect whether the oleophobic coating is sprayed fully or evenly on the screen, just shake the phone at will. If the water drops can “dance” on the screen without any hindrance, congratulations, the tempered glass has been treated with an oleophobic coating.
The other simple way is to write on the display with a marker pen and try to clean it with a cloth, check if markers can be easily wiped off.
We have a video to show you:
But not enough, the oleophobic coating with a bad spraying process will be worn away in a short time.
As a purchaser, you need to care about the processing technology of the oleophobic coating. For example, oleophobic coating with plasma spraying or vacuum metalizing process will be good products. Therefore, it is worth buying if the specification of a tempered glass film is shown as a treatment of plasma or vacuum metalizing option.
As a professional manufacturer of tempered glass films, the oleophobic coating quality is strictly measured by professional test instruments such as a goniometer and abrasion resistance tester.
A goniometer or tensiometer measures the contact angle between a droplet and a surface, this is to test if the oleophobic coating is well treated.
The contact angle measurement is a method to measure the spraying quality & durability of oleophobic coating on the glass. Drop a liquid on the glass, and measure the contact angle between the tempered glass (with oleophobic coating) and the droplet. The more the contact angle is, the better quality oleophobic coating will be. The contact angle of glass with a well-treated oleophobic coating is typically between 105-120°.
The abrasion resistance test is implemented by an abrasion tester which is a machine that measures material wear due to sliding contact. Put the test sample under a specific load on the machine, using rubber, alcohol cotton cloth, or steel wool to rub the surface in specific friction cycles, and then measure the contact angle again by a goniometer.
The abrasion resistance test is usually combined with the contact angle parameter to judge the quality of the oleophobic coating, the durability of oleophobic spray is comprehensively judged by the comparison of the contact angle before and after the abrasion resistance test.
According to the mobile phone tempered film industry standard, when the initial contact angle is greater than or equal to 110°, it is considered a qualified mobile phone tempered film, the contact angle with 100-110° after abrasion resistance test will be considered a qualified product according to different friction cycles, load or materials used for rub.
Will the oleophobic coating wear off?
Unfortunately, oleophobic coatings on either tempered glass films or mobile phone displays will gradually wear off after a period of use, as screens are touched every day by fingers other objects, the oleophobic coatings are being rubbed and worn away.
A qualified tempered glass film can naturally maintain its oleophobicity for a longer period, while a low-quality oleophobic coating will last a very short time.
When the mobile phone is plated with oil-based coating, a higher concentration AF coating can be maintained within 1 year, and if the concentration is low, it will
Generally speaking, a tempered glass film with a higher concentration of oleophobic coating can last more than 6 to 12 months, while the lifetime of the one with low concentration will be shortened accordingly, for example, some low-quality ones might last only several days.
How to protect the oleophobic coating from being ruined?
The oleophobic coating is “easy consumables”, which will gradually wear off with frequent use, and hydrophobic or oleophobic features will gradually weaken. There are still some tips to try to protect the oleophobic coating from being worn off in a short time.
The main ingredient of the oleophobic treatment is nano-silicon dioxide, and the method of cleaning this kind of chemical is cleaner such as washing powder, so please do not clean the screen or tempered glass film with cleaners such as Windex or other window cleaner, crème cleansers, detergents, washing powder or dishwashing liquid, bleach or other bleach-based cleaning agents, the Oleophobic coating also “scare” polishes or abrasive cleaning agents, they might remove the oleophobic coatings completely. All of these will definitely ruin the oleophobic coatings.
It is enough to use a soft, lint-free cloth to clean your screen, moisten it with water and wipe off any visible grime and dirt.
How to restore/refresh oleophobic coating
The oleophobic coatings cannot be restored. If your mobile phone does not have a protective film or the oleophobicity becomes poor, you can easily apply a mobile phone screen protector to solve the problem, at present, almost all mobile phone films, especially tempered glass films, have an oleophobic coating on the surface, it’s just a matter of good or bad quality.
The oleophobic coating application kit may be the other solution to refresh the oleophobic effect for your mobile phone screen. Oleophobic coating kit is a kind of liquid contained in a small bottle, drop the liquid on the mobile phone display, and then apply it evenly on the entire screen, wait for it to dry and cure completely.
Oleophobic coating kit is declared to be able to restore and improve the anti-fingerprint oleophobic properties of the glass surface, normally it has similar ingredients as the original oleophobic coating on the screen or tempered glass film, but we do not recommend that consumers use an oleophobic coating kit to refresh oleophobicity. Readers may understand from this article now that the spray process of oleophobic coating on glass screen or tempered glass film does matter the effect and lifespan of oleophobicity. The oleophobic coating can be hardly applied firmly on the glass surface by the process of manual spray, it usually wears off in a very short time, it is not reliable and durable, so you can imagine how long the oleophobic coating will last by applying with oleophobic coating kit manually. Although oleophobic coating kits are sold at an inexpensive price, they are still not a cost-effective way, that’s also why the ratings of these kinds of products are not very low.