The issue, now dubbed "Tattoogate," stems from the interference of the ink pigmentation with the sensor's ability to read your heart rate. The high-end watch needs this sensor to assess if the user is wearing the watch; according to Apple, the Watch's green and infrared light is either absorbed or reflected through your skin, allowing it to read your heart rate.
"So I thought my shiny new 42mm SS watch had a bad wrist detector sensor," wrote Reddit user guinne55fan on Tuesday, receiving over 700 upvotes and 300 comments. "The watch would lock up every time the screen went dark and prompted me for my password. I wouldn't receive notifications. I couldn't figure out why especially since the watch was definitely not losing contact with my skin."
With a full sleeve tattoo on his left arm, he tried holding the Watch against his hand and it began to work. However, once he put it back on the area that is tattooed with black ink, the watch automatically locked.
YouTube user Michael Lovell also experienced similar issues, which he demonstrated on both his tattooed and non-tattooed arms.
The Apple blog iMore followed up with a report confirming the issue, and after conducting their own series of tests, they found that dark, solid colors are responsible for the most heart rate misreadings (196 BPM before failing to read entirely). Lighter tattoo colors produced slightly elevated heart rate misreads but did not appear to interfere with the Watch's ability to register skin contact.
For those with issues with the Watch's sensors, you can turn off the Wrist Detection on the Apple Watch app to avoid auto-locking, although this will also disable Apple Pay.
It is important to note that the Apple Watch works fine with dark-colored skin and scars, and Apple offers a 14-day return policy.