[Feen]

Tried to find answer here but haven't managed. Lots of modern builds (i.e. 15 years old) have stains that I can't remove. Look like water dried on glass, some below a drip. No amount of rubbing, MDR etc removes them.
In contrast, cleaned house today where glass must be 150 year old and its beautiful. Modern glass is inferior, but any ideas here?

[Dave Willis]

I wrote a snotty note to one of my customers today. For some reason someone in her household sprays the whole of the conservatory and lower windows round the back with a hosepipe with tds around 300. I'm sick of scrubbing limescale off - her windows are in effect ruined. Told her to stick it.

[James Bulton]

Its calcium oxide coming of the brickwork and also new rendering.It will not come of with a scraper and hen wet its looks as if its gone only to reappear wet dry.
I use doctor power as white paste you apply on wet glass and rub in small circles over the hole sheet of glass its not easy to get off.I used a small sanding pad that fits on a battery drill with a mop head. I have seen them on e bay to repair headlights scratches.Its not really window cleaning but restoring. I charge 10 /20 quid for  sheet of glass if its on a house.If you do not get it off it ill get worse and you ill have to replace the unit these few words make 20 quid sound like a bargain. After the buffing ash the glass and feel for gritty spots and if its clean clean as you normally do.I have found it bad on these new builds with french doors with a glass sheet in front of the doors to form a balcony.Good luck. Ps I make a few bucks cleaning shower doors the same way.

[Rob Knapman]

Yes I agree, new glass dont seem to be as 'tough' as the old stuff, it stains far more easier, I have a few where waterproofer has been sprayed over walls and windows = ruined glass!!!!!

[sf]

try unger rub out

[Feen]

Thanks all for your advice. Will try your ideas and see how I get on

[paulben]

Try CIF works for me