Based on the experience of some people on Reddit, anyone opting for an Apple Watch with an aluminium case should perhaps bear one thing in mind: Your body chemistry can affect the durability of the watch’s case.
On r/AppleWatch, Spirited-Ad-5977 posted a picture of their 6-year-old Apple Watch. The case and its holes look like Swiss cheese. Other photos show elongated gullies. The case looks damaged, but the original poster doesn’t provide any details besides the photos, asking simply, “What is happening to the body?”
It appears that the Apple Watch in question is experiencing a type of corrosion called pitting corrosion. Most responders on Reddit suspect it is due to the chemistry of the sweat of the original poster. The aluminium coating on the Apple Watch could be reacting with the chloride ions from sodium, which reach the skin via the sweat.
The chloride ion reacts with the oxidized layer of the aluminium casing and displaces the oxygen from the compound. This breaks through the oxidized layer. The metal underneath reacts with further chloride ions that reach the area. This creates a localized acidic environment that continues to eat its way inwards, creating the pits on the Apple Watch. Some responders wonder if some lotions or creams have an effect on the case.
This seems to be an isolated incident between the Reddit poster and their Apple Watch. Everyone sweats differently in terms of quantity, intensity, and chemistry. It’s not common to hear about this problem, but it’s not a new one to watch makers in general. The Swiss watch industry has a dedicated standard that specifies the case’s resistance to external chemical influences. Some laboratories immerse watches and their straps in artificial sweat to determine whether the watch is resistant to it.
Apple doesn’t appear to have any support documentation addressing the specific issue of sweat and the Apple Watch. But Apple does have a detail document on how to clean your Apple Watch, which you should do regularly. The document also has tips to avoid skin irritation, or if you have allergies or skin sensitivities.
