Podcast:99% Invisible Published On: Tue Sep 12 2017 Description: Coal miner stickers started out as little advertisements that the manufacturers of mining equipment handed out. Even before the late 1960s, when mining safety laws started requiring reflective materials underground, miners used those stickers to stay visible to each other in the dark mines. As time passed, the stickers evolved. They became more personal and started to tell miners’ stories. And the mine companies themselves started printing stickers for their workers. Stickers went from simple ads to signifying an identity. And as their role changed, stickers also came to serve as a kind of currency among miners. Coal Hogs Work Safe Subscribe to SiriusXM Podcasts+ on Apple Podcasts to listen to ad-free new episodes and get exclusive access to bonus content.