[Cleaner Windows]

one question I've always wanted to ask: has anyone ever come across windows that look roughly pitted with what looks like rust around and/or in the pitted marks?
I've seen it a few times now and could only guess how it happens, I've seen it on old glass and on new, someone please enlighten me?

regards

Denis

[Ian W]

I can only guess that someone has used a welder or grinder nearby. I have seen it on one of the windows on my round and think it was to do with builders installing steelwork on a new extension.

[michael papworth]

A bit far-fetched maybe, but could it be cosmic in origin?

Meteorites are iron rich. I have some marks on one of my windows which I have just inspected. They seem to be parallel and could conceivably have been caused by microscopic and very hot particles striking the window panes.

One of the windows is new and there's been no iron working done in my back garden to cause sparks.

[Cleaner Windows]

I can only guess that someone has used a welder or grinder nearby. I have seen it on one of the windows on my round and think it was to do with builders installing steelwork on a new extension.

thats exactly what I thought could have caused it but if you've ever done any grinding, those bits that fly off don't really hit you that hard at all, so it makes me wonder how it could damage the glass 

[Cleaner Windows]

A bit far-fetched maybe, but could it be cosmic in origin?

Meteorites are iron rich. I have some marks on one of my windows which I have just inspected. They seem to be parallel and could conceivably have been caused by microscopic and very hot particles striking the window panes.

One of the windows is new and there's been no iron working done in my back garden to cause sparks.

gotta admit, I do like your idea but I wonder how likely that would be   

[WCE]

I see this all the time on new build sites. It is caused by a grinder. It completely wrecks the glass too!

[jmb]

the damage you get from someone grinding near a window
is because of the temperture of the tiny bits of metal that
hits the glass making it pit. 

[AuRavelling79]

Had this on an upstairs window when I was trad.

The cast iron soil pipe had been replaced with new plastic and was lying in cut up sections on the ground. It had been cut near the bathroom window and that's where the marks came from.

The sparks are tiny white hot pieces of ground (cut) metal which are flung against the glass causing pitting or even embedding into it.

In the moisture they soon turn to ferrous oxide (rust) and appear as tiny brown rough dots.

[dave0123]

it is a grinder, i have them on my windows from a grinder tiny little rust specks.

[Cleaner Windows]

they must be grinding really close then cos those hot particles cool down very quicly through the air don't they!

so now for my next question..... is there any way of getting the marks off the glass? at least just the brown bits? 

[Pj]

No.

[pjulk]

I come across this quite often also on builders cleans.

Only way to fix is have the glass replaced

[Cleaner Windows]

had a funny feeling you were gonna say that 
thanks anyway!

[*Mr Tumble]

T-cut can make quite a difference if you rub long enough.  It dulls the brown stain a lot actuall, but you never get rid of the mark 100%

Worth trying.

[Cleaner Windows]

now the sparks that come off of those ARE hot and stay hot for quite a while 

[Wayne Thomas]

It's definitely bits of hot mild steel that has embedded in the glass from a grinder. I would not recommend trying to remove it as the glass itself is actually damaged. If you try using a scraper you'll just leave scratch marks all over the glass making the whole thing worse. The customer has two choices: 1. Live with it or 2. replace the glass.
If the customer used a tradesperson tell them to inform the tradesman/woman that they damaged the glass and to claim on his/her insurance.

[Ian W]

I used to be a welder and used grinding machines too. Both are quite capable of leaving marks in glass. I suspect it is a grinding machine used by a builder though, if it is in a domestic environment.

[Pure H20 Cleaning Services]

Stihl saw ( no much better now thankyou )

[NWH]

I`ve come across this a few times and it is either sparks flying off from a grinder or welding normally having been done above the window.Rust starts to form round the outside of the tiny holes in the glass sometimes as theres still tiny bits of metal still there.

[Cleaner Windows]

Stihl saw ( no much better now thankyou )

lol I'll have to mention that one to my brother (tree surgeon)