In an updated support document, Apple has acknowledged what some new Apple Watch owners quickly discovered over the last week: the Watch may not work properly for those with tattoos. The Watch's heart-rate monitor works by shining infrared or green light through the skin, but tattoos can interfere with that and prevent the Watch from getting a reading. "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."
Apple's description is vague about what type of tattoos will and won't pose a problem, perhaps because it doesn't precisely know....
Apple confirms that tattoos are a problem for the Apple Watch
