[Jonny D]

Hi can anyone help I have been cleaning this house for over a year with no problem until I went there on Friday. He said that the last time I was round that some of the windows had marks left on them. So I went and had a look and there was some marks there but I couldn't remove them with the pole or doing it the old way. He said he had contacted the window company because they are still under warranty but the said it must be your window cleaner, it must be something he's using in his water that's when I said I only use pure water there's nothing in it but I have no idea how these marks came about or how to get rid of them

Here's a picture of it
http://s1068.photobucket.com/user/jonx06/media/All/image.jpg.html

Any help would be appreciated thanks.

[andyM]

I would try a limescale remover like Viakal or Cillit Bang etc. to see if that would remove the marks.

[steve123]

Are you sure its on the outside of the glass? Maybe the seal has broken and its between the panes in the vacuum joint?

[windymiller]

Is the house rendered or had building work done? usually see this on houses with pebble dash or render when there is something in the cement when rains usually runs down onto the glass and that damages - eats into the glass.
Only remedy to replace the glass.

[Jonny D]

Ill go back today and take a picture of the full house and see if that helps and look to see if I can see if its inbetween the glass. If it is of the rendering is that my fault or will the company he got the window of have to take the blame?

[windymiller]

If its to do with rendering/cement its not your fault as this would have happened anyway when it rained. Ive come across this alot, usually on rendered houses where the lime out of the cement has etched into the glass.

[Ian Lancaster]

Is that lead stuck on the outside?  If there's a lead strip all round the edge of the glass it could be a chemical reaction resulting in some kind of lead salt, similar to limescale being left behind when the water evaporates.  The pattern of the drops also suggests that it is contaminated water that drips down after the window is cleaned - check to see if there is any damage to the lead strip where water could be retained and run down afterwards - like happens with two fanlights above a single wide pane - water hangs in the fanlight frames and then runs down over the glass below, leaving a line of drop marks down the centre.

Whatever the cause, it's nothing to do with you - the substance that's made the marks has to have been there before you cleaned the windows - all you put on there is pure water.

The glazing company is obviously going to try to blame someone else - I doubt it's their fault either but they're clutching at straws saying it has to be you.

Cheers,

Ian 

[Tom White]

It's hard water marking.  Rain is running down the building, picking up impurities on the way down, depositing it onto the glass and the sun is drying it on.

It's very hard to get off; I've tried all sorts over the years including Cillit Bang.

Now I just explain what I've explained here, give it a best effort with a scraper - if it's on a ground floor - and don't worry about it.

If it causes my customer any problems, they can find another window cleaner who is willing to go to more effort than me.

It's got nothing to do with the way you're cleaning them though.

[Tom White]

If its to do with rendering/cement its not your fault as this would have happened anyway when it rained. Ive come across this alot, usually on rendered houses where the lime out of the cement has etched into the glass.

Yes, I agree, but I've also seen it windows with normal brickwork too. 

[trippyboy]

viakal and scraper,if that don't work then the limescale has damaged the glass permanently.

[windowswashed]

I have a customer with limescale run marks over just one pair of his patio doors where the rain water runs onto the glass below as the builder didn't put a lintel in of the right specification as on the plans and the owner is taking the builder to court over the matter as limescale is buiding up on the glass to extremes.

I did get 99 percent off with a scraper but it's a total waste of time as the following month it builds back up on the glass.

[rosskesava]

I've found for lime scale on glass viakal, etc, is all but useless unless it's very recently deposited lime scale.

I use diluted patio cleaner as it's an acid. I dilute it 1:4 as over the years, I've found that works best.

Wet the brick work underneath the window first and also wet ground/floor/patio/etc. Spray on with a hand spray bottle fairly generously to give a light even wetting on the affected area on the glass and use a sponge with a green abrasive bit on it. It takes seconds to remove the lime scale and then rinse off with plenty of water not because patio cleaner will affect the glass in any way, but because of streaks from the run off over the brick work, etc.

Patio cleaner will discolour aluminum, metal, stainless steel (door handles) etc, so be carefull and wear latex gloves and make sure you don't breathe the spray by mistake.

I used to do one house 2 monthly that was a well priced job and they had a dripping over flow that drippped over a ground floor window. Using patio cleaner it took seconds to remove the lime scale.