A video on TikTok went viral after the user tested these color-changing dots that tell you when to reapply sunscreen.
The SpotMyUV Detection Stickers are supposed to warn you when you need more SPF.
Our editor tested the SPF-detection dots to see if they really work.
During an afternoon TikTok scroll, I came across a video by user @skinbyhelen where she slathered sunscreen over a purple dot on her skin that she claimed could "let you know when to reapply," for full protection against UV rays. In the video, Helen said that after putting on the SpotMyUV Detection Sticker ($8-$26), it turned clear in about 30 seconds. Then, it turned back to purple whenever it was time for her to reapply sunscreen. Curious about what the sticker was and whether or not it would leave a mark on my deeper skin complexion, I reached out to the SpotMyUV team and was sent a few packs to try.
Waiting for the stickers to arrive, I hopped over to the SpotMyUV website to figure out how they work. Turns out, each purple sticker has three layers: the top layer detects the amount of SPF, the middle layer has what the site calls a "non-toxic ink" that senses UV light, and the last layer is an adhesive that the site claims is resistant to sweat. Once SpotMyUV arrived, I read the instructions on the back of the package that mirrored what Helen said in her video. I also read that the dots are supposed to turn clear in direct sunlight, so I took my laptop outdoors for a few hours to put the stickers to the test.
To get SpotMyUV onto my forearm, I peeled it from the package using the perforated triangle (pictured above), then gently laid it onto my skin and gave it a firm press, so I knew it wouldn't fly off. I then grabbed my portable Sport Sunscreen Spray SPF 30 ($3) from Target and sprayed a generous layer of sunscreen over the purple dot. (The sunscreen's directions say to reapply every two hours, FYI.) Within a minute the sticker went from purple to clear, just like it did in the TikTok video. However, my results were a bit different.
Over the course of four hours, I worked in the sun yet my SpotMyUV dot stayed clear, despite light hitting my skin the entire time. Curious as to why my purple dot wasn't turning purple again, I went into the shade and turned to SpotMyUV's FAQ section to find the answer. Per the sticker-maker's site, the color-changing abilities of the purple dots are affected by the current UV index, amount of time spent in the sun, type and amount of SPF used, and activities done while wearing the purple dots. Because I was just sitting under the sun, it could've been a low UV day - or my sunscreen was putting in work.
While I am impressed by the SpotMyUV stickers' ability to detect the sunscreen on my skin, stay on my arm for hours, and not leave an awkward circular tan line in its place, I definitely want to give it another test on a stronger UV day before I give SpotMyUV a full five-star rating.