What is this mysterious blue powder that keeps collecting on the inside of our window and sill?
Our home was built in 1989 and all of the windows are original. We purchased the house in 2010 and it had the original builder grade trim on all the windows and sills. This window was a little cruddy on the inside when we bought the house, but we chalked it up to the fact that the house sat vacant for several months after foreclosure. But we had the trim replaced and it is a custom made casement. We're stumped as to the source and the identity of this mysterious blue powder. We've simply been vacuuming it up and wiping the window to remove it periodically.