Apple blog iMore performed some tests in response to the complaints and determined the Apple Watch indeed has a problem with tattoos. The blog said some tattoos interfere with the ability of the flashing lights to be reflected or absorbed by the wearer's red blood cells and the device then reacts as if it is not being worn.
"We tested the watch's sensors against tattooed and non-tattooed sections on both the wrist and elsewhere on the body. On non-tattooed non-wrist sections, the sensors gave identical readings as when also tested on the wrist; on tattooed sections, sensor readings varied wildly depending on colors and shading," the blog said.
The iMore testers said the watch has the most trouble with red and black solid-color tattoos, while lighter colors of ink could also cause problems including heart rate misreads.
Users said they were able to use the watch without it locking when they turned off the "Wrist Detection" feature, but that setting disables Apple Pay and the watch's ability answer phone calls.
