The covers included in the boxes of the mobile devices from manufacturers such as Xiaomi, Oppo or Samsung have a problem, and that is that they always have a cream or yellow tone. This change in color, even if it is attempted, unfortunately cannot be avoided due to the material used in its manufacture: TPU (Thermoplastic Polyurethane).
This polymer has many characteristics that make it ideal for manufacturing the first cases for smartphones. Its degradation, however, is what causes the gradual transition of the hue of the material.
The covers have a simple function: that of protect devices of possible blows or falls and, additionally, modify its external appearance. The transparent polymer does not meet the latter, but it is a favorable material due to its resistance to heat, its great damping capacity and its resistance to fats or oils.
In addition, for the most eco-friendly users, TPU is recyclable and can be applied in elastic textile fibers, 3D printing, car components, shoe soles, among other industrial uses.
These advantages and the low cost of their production is what makes it possible for transparent cases to be included in the set of initial smartphone accessories.
The main problem with these covers, as mentioned before, is that when they degrade, their hue changes and returns to the original state of the polymer, which is yellowish. This process is produced by the contact of the casing with sunlight, which causes changes in the material at the molecular level thanks to the heat it produces.
Buy another cover is better
Cases, both TPU and silicone, degrade due to exposure to the sun and outside heat. That is why the question about whether there is any method to prevent this from happening or to reverse the process is natural. However, this is not possible no matter how many chemicals are used in the casing.
“Tricks” such as using soap and water, cleaning the cover with isopropyl alcohol, or dipping it in bleach are not effective and are a waste of time if you want to return the material to a transparent state. What they do do is disinfect and clean the casing but, as mentioned before, the color change is due to the degradation of the polymer and not to dirt accumulated on it as a result of its constant use.
If you take into account that the material is recyclable, then the ideal for those people who are bothered by the yellowish tone of the cover is to buy a new one after a while.
In addition, the degradation period of the polymer of the covers is not fast, but it takes several months to reach the yellow color, so that in a period of between 2 and 3 years of useful life of the devices, it is estimated that in that time Only a couple of them will be used.