These cute sunscreen stickers have taken social media by storm. But how do they work? What are they for?
UV stickers are designed to indicate when your sunscreen needs to be reapplied. You stick one on an exposed area of skin and apply sunscreen normally, applying to the sticker as well. When the sunscreen breaks down and needs to be reapplied, the sticker changes colour.
These stickers are made with photochromic ink. Just like transition lenses in glasses, they start off clear but then darken in the sun. This is because the ink contains molecules that change their structure when exposed to UV light, resulting in a darkened appearance. The top layer of these stickers mimics the skin and absorbs sunscreen in a similar way.
When you apply the sunscreen to the top layer, it protects the bottom from UV rays. As the sunscreen breaks down, the bottom layer becomes exposed to UV rays, causing the ink to darken. This is how sunscreen stickers tell you when you need to reapply.
A study done on UV detection stickers found that people with sunscreen stickers were more likely to reapply sunscreen. However, those who acknowledged they needed reminders were the ones who got the most benefit out of using the stickers. With that said, sunscreen stickers are a good idea if you spend extended hours in the sun and want reminders to reapply your sunscreen.