Picked up a builders clean this week and went to do it this afternoon external glass first cos no one was there,went up to the upstairs bedroom window on me ladder and sprayed it first with a pump action 2 litre spray bottle just to try to loosen any dirt and stuff then looked for anything gritty and removed it then ran me applicator top to bottom and sqeegied top to bottom.As soon as I finished I saw three horizontal scratches to the left edge of the pane midway down,no way was it me but the scratch was there,you couldnt see it pre sqeegee cos the glass was that dirty.Went on to the big downstairs window and did that ok but there was a lot of tiny spots of cement which had to be carefully scraped and once loosened taken off the glass..
Went to look at the conservatory which was hacky and had one pane with cement sprayed across,looking very closely I could see at least 2 scratches already there.Small but there.
On a lot of the glass its that dirty you could miss more,stepped back had a think and thought sod it so packed me gear up and came home.
Am due to meet the builder at 4 to do the insides but I am telling him I dont want the job. Me gut instinct had been leave it,but having started it it was more hassle than I realised and going to take an age to do plus in 40 minutes was stressed out over the worry about scratches.