Roof of new Vikings stadium is self-cleaning

The Vikings’ new stadium has a large glass roof.  Which raises a fair question. Who will clean the bird droppings and stuff that could land on the roof? “The [ethylene tetrafluoroethylene] product is self-cleaning,” Vikings V.P. of public affairs/stadium development Lester Bagley recently told Bob Sansavere of the St. Paul Pioneer Press.  “It’s the largest…