With more and more people using smart phones, in order to protect their love machine, mobile phone protection shell and mobile phone screen protection film makers made a lot of money. But life is inevitably accidental, accidentally, a scratch on the mobile phone screen, designated in the mobile phone screen body, pain in the mobile phone owner ah. In order to solve the screen scratch problem of love machine, the machine-friends tried their best, so all kinds of rumored. One of the most widely used repair methods is using toothpaste to repair scratches on mobile screens.
Why can toothpaste repair scratches? Our company Repairtechhas collected related statements from the Internet. The main basis is based on the following two (the principles of the two statements are different):
1. The silicon-containing material inside the toothpaste can fill the scratches;
2. The friction agent in toothpaste can smooth the slight scratches. Toothpaste is rich in abrasives that can repair the slight scratches on the screen of a mobile phone.
So are these two arguments based on? Let's look at what ingredients are in toothpaste:
Toothpaste is a complex mixture. It is usually composed of abrasives (such as calcium carbonate, calcium hydrogen phosphate, calcium pyrophosphate, silicon dioxide, aluminum hydroxide), moisturizers, surfactants, thickeners, sweeteners, preservatives, active additives, and A mixture of pigments, flavors, etc.
According to netizens, friction agents (about 20% to 50% of the toothpaste paste) can act as a “repair”. The so-called friction agent is a very fine particle contained in the toothpaste. According to the national standard, the particle size of the abrasive agent is about 10 μm-20 μm. Commonly used friction agents in toothpaste are: calcium carbonate (CaCO3), calcium hydrogen phosphate (calcium hydrogen phosphate dihydrate, CaHPO4 • 2H2O), silicon dioxide (SiO2), and aluminum hydroxide [A1(OH)3].
Different toothpaste formulations use different friction agents. For example, calcium hydrogen phosphate and silica are used as friction agents in the United States. In India, calcium carbonate is mostly used as a friction agent. Therefore, calcium carbonate is more likely to "fill in" the scratches.
OK, assuming that the abrasive agent in toothpaste is silicon dioxide, can it fill the scratches on the screen? By inquiring toothpaste friction agent, we know that the size of the friction agent particles in the toothpaste is generally about 10μm, generally not more than 20μm, and the particle size of some friction agents such as light calcium carbonate is generally 1μm-3μm, and the human eye The minimum size that can be seen is about 50 μm or so, that is, the scratches are much larger than the particles of the toothpaste friction material, and it is difficult for the particles to fill the scratches firmly with friction alone .
So, can you use a friction agent to polish small scratches on the screen? From the physical characteristics of the commonly used toothpaste fillers, the hardness of solid calcium carbonate and silica are all aboutWhich is equivalent to the hardness of the glass screen. In theory, these two substances may play a role in polishing the screen.
However, calcium carbonate and silicon dioxide, which act as toothpaste abrasives, are treated light calcium carbonate and low-hardness composite silica. This is so because the Mohs hardness of human enamel is about 5-6, so Toothpaste industry standards stipulate that the Mohs hardness of a substance that acts as a toothpaste abrasive should be less than 5. It is generally believed that the Mohs hardness of the toothpaste abrasive is about 4 or so, so the toothpaste cannot polish the glass screen with higher Mohs hardness.
Why would a net friend think so? This may be because of an advertisement for a toothpaste manufacturer: The experimenter observed a number of small scratches under the microscope after rubbing on an organic glass plate with other brand of toothpaste. However, for toothpaste manufacturers, they have a specialized device called a toothpaste hardness tester to measure the hardness of the friction agent. The test method is to use a 5g toothpaste to rub 100 times on the slide glass. If any trace is left, it indicates that it is unqualified. From this we can see that using advertising as evidence is not so reliable.
It is also worth noting that when sanding with toothpaste, if the environment or sanding tools (such as eyeglasses) have fine sand (Mohs hardness = 7) and other impurities, it will be easier to sand the screen.
As the saying goes: Practice is the sole criterion for testing truth. Although we have analyzed why toothpaste cannot repair screen scratches, in a rigorous manner, we still have to experiment. For the sake of shooting, we specifically opened the screen of an iPad; the black circle on the iPad is a scratch we found on the screen, and the black water pen will mark the position of the scratch on the back of the iPad screen. Up.
1. Take a mobile with scratched screen