[windowwashers]

quite a few of my punters have used one of these sprayable fence treatments near cons ,the result is black/ brown spraydrift on the plastic and glass
                           
could it be this ??

defo not this.


Fosters cheers.

all that are replying thank you, please keep the replys coming, I will be highly armed when I go back to this job (it will costs me money) but will work wonders on this road I want to crack,

Ian

[windowwashers]

bump, any more ideas

[frames to panes]

Ian, i'm a bit stumped over this "mirror finish" is it a special coating or something or mirrored glass? I'm wondering if it's breaking down much in the same way as a normal mirror does with black spots?

[steve.ternent]

  Seems like the customer needs a new roof/conservatory...
Tell her that  :
Tell her you have wasted enough time on it already! 

Offer to demolish it for her!     

[Nathanael Jones]

Try products for killing algae/moss.

"mossgo" is a good one, and "chloras" is a multi-purpose chlorine based steriliser that I find helps with black spots on footpaths when I'm powerwashing (its cheap too, €16 for 5 gallons!)