[martin hulstone]

I have an industrial clean on a block of flats and some of the windows have really bad water staining, a couple look like they are frosted glass as they are so badly stained!
Can anybody recommend anything that will clean them up,if possible?
Many thanks

[martin hulstone]

does anyone know if oxylic acid would remove hard water staining?

[andyM]

I would first try a limescale remover, I use Viakal (available in supermarkets).
Spray on and leave for a couple of minutes and use a cloth to rub off.
If that doesn't work you may need a stronger mineral deposit remover.
Viakal is usually quite good in my experience.

[Smudger]

Winsol or white vinegar, may need to apply a couple of times

Darran

[sunshine windows]

I'll second winsol 550, great at lead/lime scale stains

[martin hulstone]

Thanks very much. will try....