Builders clean - a couple panes have brown metal burnt into the glass, likely from the builders using angle grinder to slice some scaffold to allow access. It's lots of brown small metallic spots embedded in the glass - i tried bronze wool with rubout, also tried scraper it takes the raised part of it off a little bit but leaves a 1-2mm mark behind - the glass is covered in this and paint spots so i have advised the building firm it needs replacing as its so embedded in the glass. They said do what you can and don't worry about results on these ones. Just wondered if there is anyway of improving these panes ? thanks