I purchased Ed Fred tile cleaner from a Ace hardware here in Mesa, AZ. a few years ago to clean the water stains from my cut glass goblets, but in doing so, I found the best scum remover ever!
At the store where I work we had some water sprinklers that were hitting some black tinted windows. Over time they were messy white encrusted windows baked in the AZ sun.
I took my bottle of Ed Fred where my manager sparingly used what was left in the bottle, and got them shiny black again.
