Has YOUR transparent phone case turned an unsightly yellow? Here’s the science behind why plastic changes color – and how to clean it

Smartphone users who opted for a transparent case to show off the tech design may have noticed the clear plastic has turned a dingy yellow.

While the change might be annoying, the truth is that the plastic used to make these covers is actually yellow – but manufacturers add a blue tint that makes them see-through.

The tint wears off exposing the original color when the case is exposed to ultraviolet (UV) light, natural oils, and sweat from the human body.

However, the off-putting tint can be transformed back to the transparent cover – and experts have shared ways to make them look as good as new.

Why does a clear smartphone case turn yellow?

Most clear smartphone covers are designed using silicone, acrylic or thermoplastic polyurethane (TPU).

All three are durable and capable of withstanding high temperatures – which can increase with smartphone use.

However, Ecmco Industrial Plastics states that ‘American-made acrylic does yellow in the sunlight.’

Polycarbonate is a type of TPU that is more shatter resistant than acrylic, which is likely the go-to material for manufacturers.

This material, acrylic and silicon all yellow due to an oxidation reaction triggered when exposed to UV light.

And a similar reaction occurs with sweat and oils.

How to clean a yellow smartphone case?

ESR, a company specializing in cases for tablets, smartphones and other devices, has shared what it calls ‘the simplest and most affordable solution.’

Mix a few drops of dish soap with warm water and gently scrub the case with a toothbrush.

And make sure to get in all the tiny cutouts and notches on the interior and exterior.

‘Finally, rinse the case and dry it with a soft cloth. You can leave it to air dry for an hour or so. If possible, repeat this process once or twice a week,’ ESR shared.

You can also use backing soda, but apply the powder dry to the case.

The grab a wet toothbrush and scrub away.

Once done, rinse the case and dry it with a soft cloth. Let it aid dry before using it on your phone.

And the final method from ESR is scrubbing alcohol.

‘Pour the alcohol into a spray bottle, using the bottle to spray the alcohol on the case. Alternatively, you can use a cloth soaked in alcohol,’ ESR’s blog post.

With the exterior and interior coated, take a soft dry cloth to remove the alcohol. Once done, let it air dry for about an hour. 

‘This will ensure it is dry enough to use on your phone.’

Another online tip, dubbed ‘Grandma’s recipe,’ calls for a mixture of baking soda, lemon juice and vinegar.

First mix the backing soda and lemon juice into a paste and apply it to the case with a toothbrush, then in a bowl with vinegar.

Let it sit for about one hour, and then rinse.