Early adopters of the Apple Watch, Apple Inc.’s first new product in five years, are complaining that a number of its key functions are disrupted by their tattoos.

Owners of Apple Watch – including this reporter, who bought a 42mm version with stainless steel case and black classic buckle for €736 – have found that their inked skin confuses the sensors on the underside of the device.

Users of the watch, which went on sale last week, took to social media yesterday under the hashtag #tattoogate to air their frustration with the flaw from Apple’s renowned design house.

One anonymous user on Reddit, an entertainment, social networking, and user-generated news website, said the device’s locking mechanism, which should disengage when the watch detects it is being worn, failed to work on decorated skin.

“My hand isn’t tattooed and the Watch stayed unlocked. Once I put it back on the area that is tattooed with black ink, the watch would automatically lock again,” the user wrote.

An Apple support article says the watch uses green LED lights paired with light-sensitive photodiodes to detect the amount of blood flowing through the wrist and calculate the frequency of heart beats.

A website support page from the company says tattoos can interfere with readings from the heart rate monitor, but does not mention interference with other functions.

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