What are those blue dots on coin cell batteries?
Yesterday a redditor named joshcam posted a photo of a coin cell battery with purple colored dots arranged in three concentric semicircles. They posted:
To the naked eye, these dots are an iridescent, deep purple, the kind of purple you see when you look at a black light.
There are three rows of dots run…
Keep reading with a 7-day free trial
Subscribe to Boing Boing to keep reading this post and get 7 days of free access to the full post archives.