Hey Pinfan
I just use my old favorite Windex and either paper towel or a really soft cloth
window can be a bit abrasive - Believe it or not, try NOVUS 2 ! Yep I didn't believe it either, until Pinfan gave me the tip that it works wonders !
Ahh NINO, you blew my cards !
Yep NOVUS 2 ! Best by far.
I keep well away from any flaking or peeling. But if you have a good clean glass. It comes up a treat.
pic 1 is BG lit up dirty.
pic 2 is bg being cleaned with novus 2.
pic 3 is bg lit up clean.