Apple admits tattoos can screw with the Apple Watch's sensors

Apple has confirmed that tattoos can screw with the Apple Watch's sensors, updating a section of its website detailing how the watch's heart rate sensor works to recognize the issue.

"Permanent or temporary changes to your skin, such as some tattoos, can also impact heart rate sensor performance," Apple writes. "The ink, pattern, and saturation of some tattoos can block light from the sensor, making it difficult to get reliable readings."

As a workaround, Apple suggests that you "connect your Apple Watch wirelessly to external heart rate monitors such as Bluetooth chest straps." 

Apple's recognition of the issue follows a week of reports from disgruntled Apple Watch customers with wrist tattoos, many of whom took to social media sites like Reddit and YouTube to document their troubles. Some even called the malfunction "Tattoo-gate."

Those with dark, blocky tattoos on their wrist noticed that the Apple Watch would fail to recognize that the device was being worn, with the dark ink of their tattoos making it difficult for the watch's infared sensor to detect the user's wrist. Since the Apple Watch uses wrist detection to recognize users and allow them to put on the device without inputting a password, some ended up disabling wrist detection and the password requirement altogether, sacrificing device security for convenience.

Because the Apple Watch uses a set of green LEDs and photodiode sensors to measure your blood flow by detecting the light absorption, it turns out the dark ink of tattoos can mess with the LED's light absorption measurements. Without the ability to measure light absorbtion accurately, those Apple Watch users were left with a watch unable to measure their heartbeat.

Tests conducted by tech blog iMore concluded that the issue "varied wildly" on a case-to-case basis depending on the "colours and shading" of the wrist tattoo.

Now that we have Apple's confirmation of the issue, if you're someone with a tattoo on the same wrist as you'd like to wear the Apple Watch, it might be time to consider trying it out on your other wrist or booking an appointment at an Apple Store so you can test how your tattoos will affect the sensors before you buy.